Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Revenues:
Natural gas sales	$ 80,351	$ 105,884	$ 127,821
Natural gas transportation	2,241,760	2,188,058	1,784,794
Natural gas storage	161,956	147,687	136,666
Other	20,246	11,113	10,600
Total operating revenues	2,504,313	2,452,742	2,059,881
Operating Costs and Expenses:
Cost of natural gas sales	80,351	105,884	127,821
Cost of natural gas transportation	53,654	50,273	38,749
Operation and maintenance	323,093	382,513	399,293
Administrative and general	184,768	217,000	189,588
Depreciation and amortization	463,757	433,480	366,566
Taxes — other than income taxes	83,687	76,632	67,537
Impairment of assets	170,128	0	0
Regulatory credit resulting from tax rate changes	(30,752)	(24,202)	(20,867)
Other expense, net	5,461	6,195	64,918
Total operating costs and expenses	1,334,147	1,247,775	1,233,605
Operating Income	1,170,166	1,204,967	826,276
Other (Income) and Other Expenses:
Interest expense - affiliate	892	2,319	60
- other	311,451	283,990	218,126
Interest income - affiliate	(132)	(89)	(7,606)
- other	(4,265)	(4,349)	(3,448)
Allowance for equity and borrowed funds used during construction (AFUDC)	(22,648)	(39,289)	(116,347)
Equity in earnings of unconsolidated affiliates	0	(3,216)	(1,068)
Miscellaneous other (income) expenses, net	4,832	2,305	(4,520)
Total other (income) and other expenses	290,130	241,671	85,197
Net Income	880,036	963,296	741,079
Other comprehensive income:
Equity interest in unrealized gain on interest rate hedges (includes $(162) and $(143) for the years ended December 31, 2019 and 2018, respectively, of accumulated other comprehensive income reclassification for equity interest in realized losses (gains) on interest rate hedges)	0	(641)	197
Comprehensive Income	$ 880,036	$ 962,655	$ 741,276