Condensed Consolidated Statement of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Net Income	$ 123,464	$ 137,150
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	132,614	130,432
Allowance for equity funds used during construction (Equity AFUDC)	(5,895)	(6,497)
Changes in operating assets and liabilities:
Receivables - affiliates	3,229	(153)
Receivables - others	11,590	(6,556)
Transportation and exchange gas receivable	1,535	(8,293)
Inventories	(8,305)	3,752
Payables - affiliates	42,430	22,402
Payables - others	(9,351)	25,716
Accrued liabilities	(8,634)	26,209
Asset retirement obligation removal costs	(23,319)	(16,495)
Other, net	17,134	(7,898)
Net cash provided by operating activities	276,492	299,769
Cash flows from financing activities:
Cash distributions to parent	(136,259)	(101,000)
Cash contributions from parent	69,000	86,000
Other, net	(2,077)	(5,727)
Net cash used in financing activities	(69,336)	(20,727)
Cash flows from investing activities:
Property, plant and equipment additions, net of equity AFUDC*	(192,003)	(160,780)
Disposal of property, plant and equipment, net	10,820	(3,924)
Advances to affiliates, net	(32,342)	(99,629)
Return of capital from unconsolidated affiliates	11,327	1,925
Contributions to unconsolidated affiliates	(5,806)	(11,460)
Purchase of ARO Trust investments	(23,459)	(24,545)
Proceeds from sale of ARO Trust investments	23,993	26,655
Other, net	381	(7,332)
Net cash used in investing activities	(207,089)	(279,090)
Increase (decrease) in cash	67	(48)
Cash at beginning of period	164	148
Cash at end of period	$ 231	$ 100