Condensed Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating Revenues:
Natural gas sales	$ 31,244	$ 44,020	$ 67,474	$ 101,754
Natural gas transportation	346,004	334,464	1,042,547	976,380
Natural gas storage	34,258	34,350	88,315	103,817
Other	1,343	1,734	3,396	3,561
Total operating revenues	412,849	414,568	1,201,732	1,185,512
Operating Costs and Expenses:
Cost of natural gas sales	31,244	44,020	67,474	101,754
Cost of natural gas transportation	4,689	4,301	15,501	23,264
Operation and maintenance	83,916	70,959	225,975	202,467
Administrative and general	40,604	42,217	125,997	133,904
Depreciation and amortization	76,755	69,557	231,110	203,249
Taxes - other than income taxes	14,584	12,495	45,154	36,989
Other expense, net	12,894	13,931	41,541	45,917
Total operating costs and expenses	264,686	257,480	752,752	747,544
Operating Income	148,163	157,088	448,980	437,968
Other (Income) and Other Expenses:
Interest expense	37,318	20,675	113,957	62,138
Allowance for equity and borrowed funds used during construction (AFUDC)	(19,922)	(16,476)	(45,656)	(46,725)
Equity in earnings of unconsolidated affiliates	(1,455)	(1,425)	(4,447)	(4,178)
Miscellaneous other (income) expenses, net	309	(1,193)	655	(389)
Total other (income) and other expenses	16,250	1,581	64,509	10,846
Net Income	131,913	155,507	384,471	427,122
Other comprehensive income (loss):
Equity interest in unrealized gain (loss) on interest rate hedges (includes $41 and $79 for the three months ended and $140 and $246 for the nine months ended September 30, 2016 and September 30, 2015, respectively of accumulated other comprehensive income reclassification for equity interest in realized losses on interest rate hedges)	156	(167)	(128)	(170)
Comprehensive Income	$ 132,069	$ 155,340	$ 384,343	$ 426,952