Condensed Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Revenues:
Natural gas sales	$ 25,251	$ 15,095
Natural gas transportation	426,579	362,565
Natural gas storage	34,767	34,889
Other	2,639	1,167
Total operating revenues	489,236	413,716
Operating Costs and Expenses:
Cost of natural gas sales	25,251	15,095
Cost of natural gas transportation	13,074	5,007
Operation and maintenance	87,016	72,713
Administrative and general	46,381	44,116
Depreciation and amortization	83,224	77,478
Taxes - other than income taxes	18,438	16,908
Other expense, net	17,841	15,222
Total operating costs and expenses	291,225	246,539
Operating Income	198,011	167,177
Other (Income) and Other Expenses:
Interest expense	45,074	37,257
Allowance for equity and borrowed funds used during construction (AFUDC)	(26,608)	(23,030)
Equity in (earnings) loss of unconsolidated affiliates	1,590	(1,021)
Miscellaneous other (income) expenses, net	(1,961)	(885)
Total other (income) and other expenses	18,095	12,321
Net Income	179,916	154,856
Other comprehensive income:
Equity interest in unrealized gain on interest rate hedges (includes $6 for 2018 and $15 for 2017 of accumulated other comprehensive income reclassification for equity interest in realized losses on interest rate hedges)	405	35
Comprehensive Income	$ 180,321	$ 154,891