Statement of Cash Flows (Unaudited) (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
OPERATING ACTIVITIES:
Net income	$ 110,303	$ 109,934
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation	67,616	65,766
Regulatory credits	(800)	(1,232)
Amortization of deferred charges and credits	1,277	1,864
Allowance for equity funds used during construction	(1,005)	(1,492)
Changes in current assets and liabilities:
Trade accounts receivable	3,235	5,008
Affiliated receivables	6	4,180
Exchange gas due from others	6,858	7,342
Materials and supplies	539	(48)
Other current assets	(887)	(276)
Trade accounts payable	(864)	7,693
Affiliated payables	(1,944)	(13,591)
Exchange gas due to others	(6,858)	(7,342)
Other accrued liabilities	17,436	15,806
Changes in noncurrent assets and liabilities:
Deferred charges	(1,757)	(3,105)
Other deferred credits	3,535	5,118
Net cash provided by operating activities	196,690	195,625
FINANCING ACTIVITIES:
Proceeds from issuance of long-term debt	0	8,000
Retirement of long-term debt	0	(8,000)
Capital contributions from parent	4,400	4,000
Distributions paid	(94,000)	(114,780)
Other	1,450	(1,106)
Net cash used in financing activities	(88,150)	(111,886)
Property, plant and equipment -
Capital expenditures	(72,456)	(84,958)
Proceeds from sales	(11)	4,638
Advances to affiliates	(36,072)	(3,425)
Net cash used in investing activities	(108,539)	(83,745)
NET INCREASE (DECREASE) IN CASH	1	(6)
CASH AT BEGINNING OF PERIOD	5	402
CASH AT END OF PERIOD	$ 6	$ 396