Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net income	$ 384,471	$ 427,122
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	231,110	203,249
Allowance for equity funds used during construction (equity AFUDC)	(37,285)	(35,829)
Changes in operating assets and liabilities:
Receivables - affiliates	341	(77)
Receivables - trade and other	17,045	(12,364)
Transportation and exchange gas receivable	(216)	1,957
Inventories	13,617	6,248
Payables - affiliates	(23,340)	(10,558)
Payables - trade	6,041	(1,689)
Accrued liabilities	61,484	(2,938)
Asset retirement obligation removal costs	(2,688)	(2,530)
Other, net	27,212	23,166
Net cash provided by operating activities	677,792	595,757
Cash flows from financing activities:
Proceeds from long-term debt	998,250	0
Retirement of long-term debt	(200,000)	0
Payments for debt issuance costs	(8,235)	0
Cash distributions to parent	(350,000)	(374,000)
Cash contributions from parent	372,000	491,000
Other, net	0	(1,842)
Net cash provided by financing activities	812,015	115,158
Cash flows from investing activities:
Property, plant and equipment additions, net of equity AFUDC	(906,105)	(953,383)
Contributions and advances for construction costs	157,545	63,132
Disposal of property, plant and equipment, net	(4,439)	(3,683)
Advances to affiliate, net	(718,279)	182,546
Return of capital from unconsolidated affiliates	2,106	1,331
Purchase of ARO Trust investments	(61,086)	(52,409)
Proceeds from sale of ARO Trust investments	38,330	33,778
Proceeds from insurance	2,121	16,040
Other, net	0	1,560
Net cash used in investing activities	(1,489,807)	(711,088)
Increase (decrease) in cash	0	(173)
Cash at beginning of period	0	173
Cash at end of period	0	0
Increase to property, plant and equipment, net of equity AFUDC	(907,023)	(959,894)
Changes in related accounts payable and accrued liabilities	918	6,511
Property, plant and equipment additions, net of equity AFUDC	$ (906,105)	$ (953,383)