Statement of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
OPERATING ACTIVITIES:
Net income	$ 101,408	$ 110,303
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation	69,780	67,616
Regulatory credits	(441)	(800)
Amortization of deferred charges and credits	1,192	1,277
Allowance for equity funds used during construction	(1,213)	(1,005)
Changes in current assets and liabilities:
Trade accounts receivable	1,254	3,235
Affiliated receivables	2,250	6
Exchange gas due from others	1,604	6,858
Materials and supplies	493	539
Other current assets	(704)	(887)
Trade accounts payable	(765)	(864)
Affiliated payables	504	(1,944)
Exchange gas due to others	(1,604)	(6,858)
Other accrued liabilities	17,222	17,436
Changes in noncurrent assets and liabilities:
Deferred charges	(3,741)	(1,757)
Other deferred credits	4,677	3,535
Net cash provided by operating activities	191,916	196,690
FINANCING ACTIVITIES:
Capital contributions from parent	3,530	4,400
Distributions paid	(107,500)	(94,000)
Other	(1,205)	1,450
Net cash used in financing activities	(105,175)	(88,150)
Property, plant and equipment -
Capital expenditures	(90,798)	(72,456)
Proceeds from sales	5,397	(11)
Advances to affiliates	(1,277)	(36,072)
Net cash used in investing activities	(86,678)	(108,539)
NET INCREASE IN CASH	63	1
CASH AT BEGINNING OF PERIOD	37	5
CASH AT END OF PERIOD	$ 100	$ 6