Asset Retirement Obligation Disclosure [Abstract] Statement [Table] Statement [Table] ARO Assets [Axis] ARO Assets [Axis] ARO Assets [Axis] ARO Assets ARO Assets [Domain] [Domain] for ARO Assets [Axis] Other ARO Assets Other ARO Assets [Member] Other ARO Assets [Member] Statement Statement [Line Items] ARO Underlying Asset ARO Underlying Asset The balance of the asset underlying the Company's asset retirement obligation Commitments and Contingencies [Abstract] Commitments and Contingencies [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Jurisdiction [Axis] Jurisdiction [Axis] Statutory Accounting Practices, Jurisdiction [Domain] Statutory Accounting Practices, Jurisdiction [Domain] Loss Contingencies [Line Items] Loss Contingencies [Line Items] Contingent Residual Support Agreement, Amount Contingent Residual Support Agreement, Amount Amount of senior notes of an affiliate, the Partnership has agreed to provide contingent residual support for. Estimated litigation liability Estimated Litigation Liability Accrued Environmental Loss Contingencies, Noncurrent Accrued Environmental Loss Contingencies, Noncurrent Inventory Accounting Policies [Abstract] Inventory Accounting Policies [Abstract] Energy Related Inventory, Natural Gas in Storage Energy Related Inventory, Natural Gas in Storage Inventory, Raw Materials and Supplies Inventory, Raw Materials and Supplies, Gross Inventories Inventory, Net Natural Gas Volumes Natural Gas Volumes Volume of natural gas in MMBtu Interest Costs Capitalized Interest Costs Capitalized Income Tax Disclosure [Abstract] Federal Current Federal Tax Expense (Benefit) State Current State and Local Tax Expense (Benefit) Current Income Tax Expense (Benefit) Current Income Tax Expense (Benefit) Federal Deferred Federal Income Tax Expense (Benefit) State Deferred State and Local Income Tax Expense (Benefit) Deferred income taxes Deferred Income Tax Expense (Benefit) Total income tax expense (benefit) Income Tax Expense (Benefit) Postemployment Benefits [Abstract] Benefits Pension and Other Postretirement Benefits Disclosure [Text Block] New Accounting Pronouncements [Abstract] New Accounting Pronouncements [Abstract] New Accounting Pronouncements or Change in Accounting Principle [Table] New Accounting Pronouncements or Change in Accounting Principle [Table] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2016-02 [Member] Accounting Standards Update 2016-02 [Member] New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Operating Lease, Right-of-Use Asset Operating Lease, Right-of-Use Asset Operating Lease, Liability, Noncurrent Operating Lease, Liability, Noncurrent Present value of lease liabilities Operating Lease, Liability Leases [Abstract] Weighted-average remaining lease term (years) Operating Lease, Weighted Average Remaining Lease Term Weighted-average discount rate (%) Operating Lease, Weighted Average Discount Rate, Percent 2020 Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year 2021 Lessee, Operating Lease, Liability, Payments, Due Year Two 2022 Lessee, Operating Lease, Liability, Payments, Due Year Three 2023 Lessee, Operating Lease, Liability, Payments, Due Year Four 2024 Lessee, Operating Lease, Liability, Payments, Due Year Five Thereafter Lessee, Operating Lease, Liability, Payments, Due after Year Five Total lease payments Lessee, Operating Lease, Liability, Payments, Due Less: present value discount Lessee, Operating Lease, Liability, Undiscounted Excess Amount Revenue from Contract with Customer [Abstract] Revenue, Remaining Performance Obligation, Amount Revenue, Remaining Performance Obligation, Amount Retirement Plan Type [Axis] Retirement Plan Type [Axis] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Other Postretirement Benefits Plan [Member] Other Postretirement Benefits Plan [Member] 2020 Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months 2021 Defined Benefit Plan, Expected Future Benefit Payment, Year Two 2022 Defined Benefit Plan, Expected Future Benefit Payment, Year Three 2023 Defined Benefit Plan, Expected Future Benefit Payment, Year Four 2024 Defined Benefit Plan, Expected Future Benefit Payment, Year Five 2025-2029 Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter Quarterly Financial Information Disclosure [Abstract] Schedule of Quarterly Financial Information [Table Text Block] Quarterly Financial Information [Table Text Block] Schedule Of Net Benefit Costs [Table] Schedule of the components of net periodic benefit cost of the Company's pension nd postretirement benefit plans Scenario [Axis] Scenario [Axis] Scenario, Unspecified Scenario [Domain] Defined Benefit Plan Disclosure Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan, Service Cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Prior service credit amortization Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Fair Value [Abstract] Fair Value [Abstract] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Investment Type [Axis] Investment Type [Axis] Investments Investments [Domain] Fixed Income Securities [Member] Fixed Income Securities [Member] Equity Securities [Member] Equity Securities [Member] Available-for-sale Securities Available-for-sale Securities Investments, Fair Value Disclosure Investments, Fair Value Disclosure Debt Disclosure [Abstract] Schedule Of Debt Instruments Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Maturities of Long-term Debt Schedule of Maturities of Long-term Debt [Table Text Block] Health care cost trend rate Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year Rate to which the cost trend is assumed to decline (the ultimate trend rate) Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Statistical Measurement [Axis] Statistical Measurement [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] Maximum [Member] Maximum [Member] Minimum [Member] Minimum [Member] Major Property Class [Axis] Major Property Class [Axis] Major Property Class [Domain] Major Property Class [Domain] Equipment [Member] Equipment [Member] Real Estate [Member] Real Estate [Member] Lessee, Operating Lease, Term of Contract Lessee, Operating Lease, Term of Contract Short-term Lease, Cost Short-term Lease, Cost Schedule of Effective Income Tax Rate Reconciliation [Table] Schedule of Effective Income Tax Rate Reconciliation [Table] Schedule of Effective Income Tax Rate Reconciliation [Table] Business Combination, Separately Recognized Transactions [Axis] Business Combination, Separately Recognized Transactions [Axis] Business Combination, Separately Recognized Transactions [Domain] Business Combination, Separately Recognized Transactions [Domain] Schedule of Effective Income Tax Rate Reconciliation [Line Items] Schedule of Effective Income Tax Rate Reconciliation [Line Items] [Line Items] for Schedule of Effective Income Tax Rate Reconciliation [Table] Computed statutory income tax expense at 35% Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount State income taxes, net of federal income tax benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Non-deductible goodwill impairment Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Amount Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Effective Income Tax Rate Reconciliation, Change in Tax Status of Subsidiary Effective Income Tax Rate Reconciliation, Change in Tax Status of Subsidiary Amount of the difference between reported income tax expense (benefit) and expected income tax expense computed b applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to the effect of a change in the tax status of a subsidiary. Related Party Transactions [Abstract] Related Party Transactions Related Party Transactions Disclosure [Text Block] Defined Benefit Plan by Plan Asset Categories Defined Benefit Plan, Plan Assets, Category [Axis] Plan Asset Categories Defined Benefit Plan, Plan Assets, Category [Domain] Cash and Cash Equivalents Cash and Cash Equivalents [Member] Market index fund [Member] Market index fund [Member] Market index fund [Member] International index fund [Member] International index fund [Member] International index fund [Member] U.S. bond index fund [Member] U.S. bond index fund [Member] U.S. bond index fund [Member] Large Cap US Equitiies Large Cap US Equitiies Percentage of mutual fund that is invested in large-cap U.S. equities. Defined Benefit Plan, Plan Assets, Amount Defined Benefit Plan, Plan Assets, Amount Fixed Income Securities Fixed Income Securities Percentage of mutual fund that is invested in fixed income securities. International Securities Funds International Securities Funds International Securities Funds Statement of Financial Position [Abstract] ASSETS Assets [Abstract] Current assets: Assets, Current [Abstract] Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss, Current Accounts receivable from related companies Due from Related Parties, Current Exchanges receivable Gas Balancing Asset (Liability) Inventories Other current assets Other Assets, Current Total current assets Assets, Current Property, plant and equipment Property, Plant and Equipment, Net [Abstract] Total property, plant and equipment Property, Plant and Equipment, Gross Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Net property, plant and equipment Property, Plant and Equipment, Net Other Assets, Noncurrent Other Assets, Noncurrent Goodwill Goodwill Total assets Assets LIABILITIES AND PARTNERS’ CAPITAL Liabilities and Equity [Abstract] Current liabilities: Liabilities, Current [Abstract] Current maturities of long-term debt Long-term Debt, Current Maturities Accounts payable Accounts Payable and Accrued Liabilities, Current Accounts payable to related companies Accounts Payable, Related Parties, Current Exchanges payable Gas Balancing Payable, Current Other current liabilities Other Liabilities, Current Total current liabilities Liabilities, Current Long-term debt, less current maturities Long-term Debt and Lease Obligation Note payable to related party Notes Payable, Related Parties, Noncurrent Deferred income taxes Deferred Tax Liabilities, Net, Noncurrent Other non-current liabilities Other Liabilities, Noncurrent Commitments and contingencies Commitments and Contingencies Partners’ capital: Partners' Capital [Abstract] Partners’ capital General Partners' Capital Account Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total partners’ capital Partners' Capital Total liabilities and partners’ capital Liabilities and Equity Revenue from Contract with Customer [Text Block] Revenue from Contract with Customer [Text Block] Beginning balance Asset Retirement Obligation Revisions Asset Retirement Obligation, Revision of Estimate Settled Asset Retirement Obligation, Liabilities Settled Accretion expense Asset Retirement Obligation, Accretion Expense Ending balance Schedule of Related Party Transactions, by Related Party [Table] Schedule of Related Party Transactions, by Related Party [Table] Related Party [Axis] Related Party [Axis] Related Party Related Party [Domain] Affiliated Entity Affiliated Entity [Member] Related Party Transaction Related Party Transaction [Line Items] Revenue from Related Parties Revenue from Related Parties Related Party Transaction, Expenses from Transactions with Related Party Related Party Transaction, Expenses from Transactions with Related Party Related Party Operating, Maintenance and General Expenses Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party Interest income — affiliates Interest Income, Related Party Interest Expense, Related Party Interest Expense, Related Party Statement of Partners' Capital [Abstract] Partner Capital Components [Axis] Partner Capital Components [Axis] Partner Capital Components [Domain] Partner Capital Components [Domain] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Limited Partner [Member] Limited Partner [Member] Balance Other comprehensive income, net of tax Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax Non-Cash Equity Contribution Non-Cash Equity Contribution Non-Cash Equity Contribution Net income (loss) Net Income (Loss) Attributable to Parent Distribution to partners Partners' Capital Account, Distributions Unit-based compensation expense APIC, Share-based Payment Arrangement, Increase for Cost Recognition Panhandle Merger Stockholders' Equity, Other Balance Taxes on Income Income Tax Disclosure [Text Block] Non-Cash Distribution [Abstract] Non-Cash Distribution [Abstract] Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Lessee, Operating Leases [Text Block] Lessee, Operating Leases [Text Block] Debt Narrative [Table] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 8.125% Senior Notes due 2019 Senior Notes due 2019 [Member] Senior Notes due 2018 [Member] Senior Notes due 2018 [Member] Senior Notes Due 2029 [Member] Senior Notes Due 2029 [Member] 7.60% Senior Notes, due February 1, 2024 [Member] 7.60% Senior Notes, due February 1, 2024 [Member] 7.60% Senior Notes, due February 1, 2024 [Member] 8.25% Senior Notes, due November 14, 2029 [Member] 8.25% Senior Notes, due November 14, 2029 [Member] 8.25% Senior Notes, due November 14, 2029 [Member] Legal Entity Legal Entity [Axis] Entity [Domain] Entity [Domain] Panhandle [Member] Panhandle [Member] Panhandle [Member] Long-term Debt, Type Long-term Debt, Type [Axis] Long-term Debt, Type Long-term Debt, Type [Domain] 3.26% Junior Subordinated Notes due November 1, 2066 [Member] 3.26% Junior Subordinated Notes due November 1, 2066 [Member] 3.26% Junior Subordinated Notes due November 1, 2066 [Member] Debt Instrument Debt Instrument [Line Items] Senior Notes Senior Notes, Noncurrent Debt Instrument, Fair Value Disclosure Debt Instrument, Fair Value Disclosure Long term debt, amount outstanding Long-term Debt Repayments of Senior Debt Repayments of Senior Debt Debt Instrument, Maturity Date Debt Instrument, Maturity Date Junior Subordinated Notes Junior Subordinated Notes Unamortized Net Premiums And Fair Value Adjustments Unamortized Net Premiums And Fair Value Adjustments Unamortized Net Premiums And Fair Value Adjustments Long-term Debt, Weighted Average Interest Rate, at Point in Time Long-term Debt, Weighted Average Interest Rate, at Point in Time 2020 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2021 Long-term Debt, Maturities, Repayments of Principal in Year Two 2022 Long-term Debt, Maturities, Repayments of Principal in Year Three 2023 Long-term Debt, Maturities, Repayments of Principal in Year Four 2024 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Long Term Debt Maturities Repayments Of Principal Total Long Term Debt Maturities Repayments Of Principal Total The total amount of repayment principal due on long-term debt maturities. Asset Retirement Obligations Asset Retirement Obligation Disclosure [Text Block] Accounting Policies [Abstract] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Asset Impairment Charges Asset Impairment Charges Operating revenues Revenues Operating income Operating Income (Loss) Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Minimum [Member] Maximum [Member] Savings Plan [Member] Savings Plan [Member] Savings Plan Supplemental Employee Retirement Plan [Member] Supplemental Employee Retirement Plan [Member] Equity Securities Fixed Income Securities Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Defined Contribution Plan Employers Matching Contribution Percentage to Participants Percentage Conribution Defined Contribution Plan Employers Matching Contribution Percentage to Participants Percentage Conribution The percentage of the employer's matching contribution to a participants defined contribution plan as a matching contribution to the participants percentage contribution. Other securities Other securities Percent of mutual fund that is invested in other securities. Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Arising During Period, before Tax Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Mortgage-backed securities Mortgage-backed securities Percent of mutual fund that is invested in mortgage-backed securities. Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year Defined Contribution Plan, Employer Matching Contribution, Percent Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Company Contributions Vested Company Contributions Vested Percentage company contributions are vested after five years. Company Contributions Years Company Contributions Years Number of years of continuous service when company contributions are fully vested. Defined Contribution Plan, Cost Defined Contribution Plan, Cost Organization, Consolidation and Presentation of Financial Statements [Abstract] Description of the Business Nature of Operations [Text Block] Contract with Customer, Asset, after Allowance for Credit Loss Contract with Customer, Asset, after Allowance for Credit Loss Contract with Customer, Liability Contract with Customer, Liability Benefit obligation at beginning of period Defined Benefit Plan, Benefit Obligation Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment Actuarial gain Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Benefit obligation at end of period Fair value of plan assets at beginning of period Return on plan assets and other Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Employer contributions Defined Benefit Plan, Plan Assets, Contributions by Employer Defined Benefit Plan, Benefit Obligation, Benefits Paid Defined Benefit Plan, Benefit Obligation, Benefits Paid Fair value of plan assets at end of period Amount overfunded at end of period (1) Defined Benefit Plan, Funded (Unfunded) Status of Plan Net actuarial gain Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Prior service cost Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax Amounts recognized in accumulated other comprehensive income (pre-tax basis) consist of: Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Tax exempt accounts Expected long term return on assets, tax exempt accounts An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invetested or to be invested to provide for the benefits included in the benefit obligation's tax exempt accounts. Expected long term reurn on assets, taxable accounts Expected long term reurn on assets, taxable accounts An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invetsed or to be invested to provide for the benefits included in the benefit obligation's taxable accounts. Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table Text Block] Cash and Cash Equivalents [Abstract] Restrictions on Cash and Cash Equivalents [Table] Restrictions on Cash and Cash Equivalents [Table] Related Party Transaction [Axis] Related Party Transaction [Axis] Related Party Transaction [Domain] Related Party Transaction [Domain] Restricted Cash and Cash Equivalents Items Restricted Cash and Cash Equivalents Items [Line Items] Non-Cash Settlement of Tax Liability Non-Cash Settlement of Tax Liability Amount of non-cash settlement of tax liabilities during the period. Settlement of affiliate liability - related party payables Settlement of affiliate liability - related party payables Amount of non-cash settlements of affiliate liabilities due from related parties. Proceeds from Contributions from Affiliates Proceeds from Contributions from Affiliates Deemed contribution (distribution) to Parent Deemed contribution (distribution) to Parent The amount of a contribution or (distribution) either cash or non-cash that is deemed to the Parent during the period. Capital Expenditures Incurred but Not yet Paid Capital Expenditures Incurred but Not yet Paid Interest Paid, Excluding Capitalized Interest, Operating Activities Interest Paid, Excluding Capitalized Interest, Operating Activities Increase (Decrease) in Notes Receivables Proceeds from Interest Received Dividends and Interest Paid Dividends and Interest Paid Property, Plant and Equipment [Abstract] Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Land and Land Improvements [Member] Land and Land Improvements [Member] Construction Work-In-Process [Member] Construction Work-In-Process [Member] Construction Work-In-Process [Member] Building and Building Improvements [Member] Building and Building Improvements [Member] Pipelines [Member] Pipelines [Member] Natural Gas, Storage [Member] Natural Gas, Storage [Member] Property, Plant and Equipment, Other Types [Member] Property, Plant and Equipment, Other Types [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Property, Plant and Equipment, Estimated Useful Lives Property, Plant and Equipment, Estimated Useful Lives Property, Plant and Equipment, Gross Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Net property, plant and equipment Legal Entity Southwest Gas [Member] Southwest Gas [Member] Southwest Gas [Member] Trunkline [Member] Trunkline [Member] Trunkline [Member] Sea Robin [Member] Sea Robin [Member] Sea Robin [Member] Goodwill, Impairment Loss Goodwill, Impairment Loss Tangible Asset Impairment Charges Tangible Asset Impairment Charges Related Party Transactions [table text block] Related Party Transactions [table text block] Tabular disclosure of the company's related party balances included in the balance sheet. Schedule of Long-term Debt Instruments [Table] Debt Instrument Total debt outstanding Less: Current maturities of long-term debt Long-term Debt, Excluding Current Maturities Long-term Debt, Excluding Current Maturities Lessee, Operating Lease, Liability, Maturity [Table Text Block] Lessee, Operating Lease, Liability, Maturity [Table Text Block] Debt Obligations Debt Disclosure [Text Block] Top Customers [Abstract] Top Customers [Abstract] Customer A [Member] Customer A [Member] Customer A [Member] Customer B [Member] Customer B [Member] Customer B [Member] Other Top 10 Customers Other Top 10 Customers [Member] Other Top 10 Customers [Member] Remaining Customers Remaining Customers [Member] Remaining Customers [Member] Entity-Wide Revenue, Major Customer, Percentage Concentration Risk, Percentage Income Statement [Abstract] Income Statement [Table] Product and Service [Axis] Product and Service [Axis] Product and Service [Domain] Product and Service [Domain] Natural Gas, Midstream [Member] Natural Gas, Midstream [Member] Product and Service, Other [Member] Product and Service, Other [Member] General partner General Partner [Member] Income Statement Income Statement [Line Items] Revenue from Contract with Customer, Including Assessed Tax Revenue from Contract with Customer, Including Assessed Tax OPERATING REVENUES: Revenues [Abstract] Total operating revenues Cost of Goods and Services Sold Cost of Goods and Services Sold OPERATING EXPENSES: Operating Expenses [Abstract] Operating, maintenance and general Operating Costs and Expenses General and Administrative Expense General and Administrative Expense Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Total operating expenses Costs and Expenses Operating Income (Loss) OTHER INCOME (EXPENSE): Nonoperating Income (Expense) [Abstract] Interest expense, net Interest Expense Income from unconsolidated affiliates Income (Loss) from Equity Method Investments Other, net Other Nonoperating Income (Expense) Total other expenses, net Nonoperating Income (Expense) Income (Loss) from Continuing Operations Before Income Tax Expense Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax expense (benefit) Net Income (Loss) Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, after Tax Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive Income (Loss), Net of Tax, Attributable to Parent Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Basis of Presentation and Significant Accounting Policies [Policy Text Block] Basis of Presentation and Significant Accounting Policies [Text Block] Consolidation, Policy [Policy Text Block] Consolidation, Policy [Policy Text Block] Use of Estimates, Policy [Policy Text Block] Use of Estimates, Policy [Policy Text Block] Accounting Changes [Text Block] Accounting Changes [Text Block] Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents, Policy [Policy Text Block] Inventory, Policy [Policy Text Block] Inventory, Policy [Policy Text Block] Natural Gas Exchanges [Policy Text Block] Natural Gas Exchanges Policy [Text Block] Disclosure of accounting policy related to recorded delivery imbalances for natural gas exchanges. Fuel Tracker [Policy Text Block] Fuel Tracker [Policy Text Block] Policy for accounting for compressor fuel volumes owed to or from customers Property, Plant and Equipment, Policy [Policy Text Block] Property, Plant and Equipment, Policy [Policy Text Block] Goodwill and Intangible Assets, Policy [Policy Text Block] Goodwill and Intangible Assets, Policy [Policy Text Block] Related Party Transactions Disclosure [Policy Text Block] Related Party Policy [Policy Text Block] Discussion of the Company's accounting treatment of related party receivables and payables. Environmental Cost, Expense Policy [Policy Text Block] Environmental Cost, Expense Policy [Policy Text Block] Revenue [Policy Text Block] Revenue [Policy Text Block] Receivables, Trade and Other Accounts Receivable, Allowance for Doubtful Accounts, Policy [Policy Text Block] Accounts Receivable and Allowance for Doubtful Accounts [Policy Text Block] Accounts Receivable and Allowance for Doubtful Accounts [Policy Text Block] - Disclosure of accounting policy for trade and other accounts receivable, including the allowance for doubtful accounts. Accumulated Other Comprehensive Loss [Policy Text Block] Accumulated Other Comprehensive Loss [Policy Text Block] The main components of comprehensive income (loss) that relate to the Company are net earnings, unrealized gain (loss) on hedging activities and unrealized actuarial gain (loss) and prior service credits (cost) on pension and other postretirement benefit plans. Pension and Other Postretirement Plans, Policy [Policy Text Block] Pension and Other Postretirement Plans, Policy [Policy Text Block] Fair Value of Financial Instruments, Policy [Policy Text Block] Fair Value of Financial Instruments, Policy [Policy Text Block] Asset Retirement Obligation [Policy Text Block] Asset Retirement Obligation [Policy Text Block] Income Tax, Policy [Policy Text Block] Income Tax, Policy [Policy Text Block] Commitments and Contingencies, Policy [Policy Text Block] Commitments and Contingencies, Policy [Policy Text Block] Schedule of Defined Benefit Plans Disclosures [Table Text Block] Schedule of Defined Benefit Plans Disclosures [Table Text Block] Schedule of Net Benefit Costs [Table Text Block] Schedule of Net Benefit Costs [Table Text Block] Defined Benefit Plan, Assumptions [Table Text Block] Defined Benefit Plan, Assumptions [Table Text Block] Schedule of Health Care Cost Trend Rates [Table Text Block] Schedule of Health Care Cost Trend Rates [Table Text Block] Schedule of Allocation of Plan Assets [Table Text Block] Schedule of Allocation of Plan Assets [Table Text Block] Schedule of Expected Benefit Payments [Table Text Block] Schedule of Expected Benefit Payments [Table Text Block] Asset Retirement Obligation, Revision of Estimate Asset Retirement Obligation, Liabilities Settled Statement of Cash Flows [Abstract] OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Net income (loss) Reconciliation of net income (loss) to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Goodwill Impairment Deferred income taxes Increase (Decrease) in Deferred Income Taxes Amortization of deferred financing fees Amortization of Debt Discount (Premium) Distributions of earnings received from unconsolidated affiliates Proceeds from Equity Method Investment, Distribution Nonmonetary Transaction, Gain (Loss) Recognized on Transfer Nonmonetary Transaction, Gain (Loss) Recognized on Transfer Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment Other non-cash Other Noncash Income (Expense) Changes in operating assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Net cash flows provided by operating activities Net Cash Provided by (Used in) Operating Activities INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities [Abstract] Proceeds from affiliates Repayment of Notes Receivable from Related Parties Increase (Decrease) in Notes Receivable, Related Parties, Current Increase (Decrease) in Notes Receivable, Related Parties, Current Capital expenditures Payments to Acquire Property, Plant, and Equipment Other Payments for (Proceeds from) Other Investing Activities Net cash flows (used in) provided by investing activities Net Cash Provided by (Used in) Investing Activities FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Distribution Made to Limited Partner, Cash Distributions Paid Distribution Made to Limited Partner, Cash Distributions Paid Proceeds from Related Party Debt Proceeds from Related Party Debt Repayments of Related Party Debt Repayments of Related Party Debt Repayments of Long-term Debt Repayments of Long-term Debt Proceeds from (Payments for) Other Financing Activities Proceeds from (Payments for) Other Financing Activities Net cash flows used in financing activities Net Cash Provided by (Used in) Financing Activities NET CHANGE IN CASH AND CASH EQUIVALENTS Cash and Cash Equivalents, Period Increase (Decrease) CASH AND CASH EQUIVALENTS, beginning of period CASH AND CASH EQUIVALENTS, end of period Summary of Significant Accounting Policies [Abstract] Summary of Significant Accounting Policies [Abstract] Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Other Current Liabilities [Table Text Block] Other Current Liabilities [Table Text Block] Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Property, Plant and Equipment [Table Text Block] Property, Plant and Equipment [Table Text Block] Schedule of Inventory, Current [Table Text Block] Schedule of Inventory, Current [Table Text Block] Revenue from External Customers by Products and Services [Table Text Block] Concentration Risk Disclosure [Text Block] Other Noncurrent Liabilities [Table Text Block] Other Noncurrent Liabilities [Table Text Block] Ownership Interest [Table] Ownership Interest [Table] Ownership Interest [Table] General partnership Limited partnership Description of the Business Description of the Business [Line Items] Description of the Business [Line Items] Limited partnership interest Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest Other Liabilities Disclosure [Abstract] Liability, Other Retirement Benefits, Noncurrent Liability, Other Retirement Benefits, Noncurrent Asset Retirement Obligation Asset Retirement Obligations, Noncurrent Other Accrued Liabilities, Current Other Sundry Liabilities, Noncurrent Other Liabilities, Noncurrent Cover page. Document Type Document Type Document Annual Report Document Annual Report Document Period End Date Document Period End Date Document Transition Report Document Transition Report Entity File Number Entity File Number Entity Registrant Name Entity Registrant Name Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Entity Tax Identification Number Entity Tax Identification Number Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Entity Address, City or Town Entity Address, City or Town Entity Address, State or Province Entity Address, State or Province Entity Address, Postal Zip Code Entity Address, Postal Zip Code City Area Code City Area Code Local Phone Number Local Phone Number Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Interactive Data Current Entity Interactive Data Current Entity Filer Category Entity Filer Category Entity Small Business Entity Small Business Entity Emerging Growth Company Entity Emerging Growth Company Entity Shell Company Entity Shell Company Entity Public Float Entity Public Float Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Amendment Flag Amendment Flag Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Schedule of Income Tax Expense (Benefit) and Effective Income Tax Rate Schedule of Income Tax Expense (Benefit) and Effective Income Tax Rate [Table Text Block] Tabular disclosure of the company's income tax expense (benefit) and effective income tax rate. Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Lessee, Leases [Policy Text Block] Lessee, Leases [Policy Text Block] Unrecognized Tax Benefits Unrecognized Tax Benefits Unrecognized tax benfits for state filing positions, net of federal tax Unrecognized tax benfits for state filing positions, net of federal tax The amount of unrecognized tax benefits net of federal tax pertaining to uncertain tax positions relating to state filing positions taken in tax returns as of the balance sheet date. Commitments and Contingencies Disclosure Commitments and Contingencies Disclosure [Text Block] Schedule of Change in Asset Retirement Obligation Schedule of Change in Asset Retirement Obligation [Table Text Block] Other Liabilities, Current [Abstract] Customer Advances and Deposits, Current Customer Advances and Deposits, Current Accrued Liabilities and Other Liabilities Accrued Liabilities and Other Liabilities Accrued Capital Expenditures Accrued Capital Expenditures The amount of obligations incurred and payable, pertaining to costs that are capital expenditures. Taxes Payable, Current Taxes Payable, Current Other Accrued Liabilities Other Accrued Liabilities Other current liabilities Other postretirement benefits Deferred Tax Assets Other Postretirement Benefits The tax effect as of the balance sheet date of the amount of estimated future tax deductions arising from other postretirement benefits. Debt amortization Deferred Tax Assets Interest Rate Derivatives The tax effect as of the balance sheet date of the amount of the estimated future tax deductions attributable to interest rate derivative instruments which can only be deducted for tax purposes when losses on such instruments are realized, and which can only be realized if sufficient tax-basis income is generated in future periods to enable the deduction to be taken. Other Deferred Tax Assets, Other Total deferred income tax assets Deferred Tax Assets, Gross Deferred Tax Assets, Valuation Allowance Deferred Tax Assets, Valuation Allowance Deferred Tax Assets, Net Deferred Tax Assets, Net Property, plant and equipment Deferred Tax Liabilities, Property, Plant and Equipment Deferred Tax Liabilities, Investment in Noncontrolled Affiliates Deferred Tax Liabilities, Investment in Noncontrolled Affiliates Other Deferred Tax Liabilities, Other Deferred Tax Liabilities, Gross Deferred Tax Liabilities, Gross Deferred Tax Liabilities, Net Deferred Tax Liabilities, Net Quarterly Financial Information [Text Block] Quarterly Financial Information [Text Block]