Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net income	$ 252,558	$ 271,615
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	154,355	133,692
Allowance for equity funds used during construction (equity AFUDC)	(20,888)	(23,123)
Changes in operating assets and liabilities:
Receivables - affiliates	(530)	223
Receivables - trade and other	16,896	(18,954)
Transportation and exchange gas receivable	(3,277)	(6,093)
Inventories	5,426	7,714
Payables - affiliates	(14,167)	8,725
Payables - trade	5,985	9,319
Accrued liabilities	39,820	(9,048)
Asset retirement obligation removal costs	(2,311)	(972)
Other, net	17,420	13,482
Net cash provided by operating activities	451,287	386,580
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	(260,000)	(233,000)
Cash contributions from parent	222,000	312,000
Other, net	0	13,539
Net cash provided by financing activities	752,015	92,539
Cash flows from investing activities:
Property, plant and equipment additions, net of equity AFUDC	(572,667)	(633,476)
Contributions and advances for construction costs	115,931	32,600
Disposal of property, plant and equipment, net	(398)	620
Advances to affiliate, net	(731,244)	118,930
Return of capital from unconsolidated affiliates	1,448	902
Purchase of ARO Trust investments	(49,427)	(42,022)
Proceeds from sale of ARO Trust investments	30,934	27,075
Proceeds from insurance	2,121	14,804
Other, net	0	1,275
Net cash used in investing activities	(1,203,302)	(479,292)
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	(596,253)	(630,346)
Changes in related accounts payable and accrued liabilities	23,586	(3,130)
Property, plant and equipment additions, net of equity AFUDC	$ (572,667)	$ (633,476)