Condensed Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues [Abstract]
Natural gas sales	$ 41,547	$ 41,757	$ 88,062	$ 96,881
Natural gas transportation	566,240	422,999	1,626,552	1,265,285
Natural gas storage	35,194	33,839	109,751	102,392
Other	2,735	2,815	8,255	7,763
Total operating revenues	645,716	501,410	1,832,620	1,472,321
Operating Costs and Expenses:
Cost of natural gas sales	41,547	41,757	88,062	96,881
Cost of natural gas transportation	15,395	9,126	38,970	30,661
Operation and maintenance	92,706	101,916	274,289	282,591
Administrative and general	49,997	44,474	155,506	137,836
Depreciation and amortization	112,296	91,670	320,103	264,176
Taxes - other than income taxes	19,316	16,622	58,253	52,224
Regulatory credit resulting from Tax Reform	(12,247)	0	(19,244)	(20,867)
Other expense, net	(6,263)	15,631	19,451	46,036
Total operating costs and expenses	312,747	321,196	935,390	889,538
Operating Income	332,969	180,214	897,230	582,783
Other (Income) and Other Expenses:
Interest expense	71,980	50,180	214,059	148,629
Allowance for equity and borrowed funds used during construction (AFUDC)	(12,640)	(43,165)	(28,857)	(104,668)
Equity in (earnings) losses of unconsolidated affiliates	(847)	(762)	(2,441)	(497)
Miscellaneous other (income) expenses, net	194	(5,537)	(1,414)	(12,317)
Total other (income) and other expenses	58,687	716	181,347	31,147
Net Income	274,282	179,498	715,883	551,636
Other comprehensive income (loss)
Equity interest in unrealized gain (loss) on interest rate hedges (includes $(24) and $(51) for the three months ended and $(153) and $(78) for the nine months ended September 30, 2019 and September 30, 2018, respectively, of accumulated other comprehensive income reclassification for equity interest in realized gains on interest rate hedges)	(93)	48	(692)	572
Comprehensive Income	$ 274,189	$ 179,546	$ 715,191	$ 552,208