Condensed Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Operating Revenues:
Natural gas sales	$ 19,937	$ 36,327	$ 36,230	$ 57,734
Natural gas transportation	338,375	319,356	696,543	641,916
Natural gas storage	34,135	34,322	54,057	69,467
Other	570	916	2,053	1,827
Total operating revenues	393,017	390,921	788,883	770,944
Operating Costs and Expenses:
Cost of natural gas sales	19,937	36,327	36,230	57,734
Cost of natural gas transportation	4,741	6,068	10,812	18,963
Operation and maintenance	73,836	63,225	142,059	131,508
Administrative and general	37,866	44,728	85,393	91,687
Depreciation and amortization	76,670	67,387	154,355	133,692
Taxes - other than income taxes	15,169	11,953	30,570	24,494
Other expense, net	17,156	14,171	28,647	31,986
Total operating costs and expenses	245,375	243,859	488,066	490,064
Operating Income	147,642	147,062	300,817	280,880
Other (Income) and Other Expenses:
Interest expense	37,817	20,656	76,639	41,463
Allowance for equity and borrowed funds used during construction (AFUDC)	(15,461)	(15,597)	(25,734)	(30,249)
Equity in earnings of unconsolidated affiliates	(1,432)	(1,234)	(2,992)	(2,753)
Miscellaneous other (income) expenses, net	(1,122)	440	346	804
Total other (income) and other expenses	19,802	4,265	48,259	9,265
Net Income	127,840	142,797	252,558	271,615
Other comprehensive income (loss):
Equity interest in unrealized gain (loss) on interest rate hedges (includes $46 and $83 for the three months ended and $99 and $167 for the six months ended June 30, 2016 and June 30, 2015, respectively of accumulated other comprehensive income reclassification for equity interest in realized losses on interest rate hedges)	(50)	50	(284)	(3)
Comprehensive Income	$ 127,790	$ 142,847	$ 252,274	$ 271,612