Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Net income	$ 1,144	$ 1,092	$ 1,371
Adjustments to reconcile to net cash provided by operating activities:
Depreciation, decommissioning and amortization	1,426	1,273	1,178
Regulatory impacts of net nuclear decommissioning trust earnings	146	189	158
Other amortization	132	106	109
Stock-based compensation	16	17	13
Deferred income taxes and investment tax credits	852	973	574
Changes in operating assets and liabilities:
Receivables	(44)	(25)	(9)
Inventory	(18)	(11)	28
Margin and collateral deposits - net of collateral received	7	2	63
Prepaid taxes	(110)	(135)	178
Other current assets	(87)	(101)	(29)
Accounts payable	11	(166)	43
Accrued taxes	4	36	(331)
Other current liabilities	(33)	118	26
Derivative assets and liabilities - net	730	(43)	(413)
Regulatory assets and liabilities - net	(1,428)	278	1,457
Other assets	(180)	(10)	48
Other liabilities	693	(207)	(395)
Net cash provided by operating activities	3,261	3,386	4,069
Cash flows from financing activities:
Long-term debt issued	896	1,135	750
Long-term debt issuance costs	(9)	(16)	(11)
Long-term debt repaid	(14)	(259)	(154)
Bonds purchased	(86)	0	(219)
Preference stock issued - net	123	0	0
Short-term debt financing - net	419	0	(1,893)
Settlements of stock-based compensation - net	(10)	(5)	4
Distributions to noncontrolling interests	0	0	(125)
Dividends paid	(520)	(352)	(351)
Net cash provided (used) by financing activities	799	503	(1,999)
Cash flows from investing activities:
Capital expenditures	(4,122)	(3,780)	(2,999)
Proceeds from sale of nuclear decommissioning trust investments	2,773	1,432	2,217
Purchases of nuclear decommissioning trust investments and other	(2,940)	(1,651)	(2,416)
Customer advances for construction and other investments	29	(3)	(21)
Effect of deconsolidation of variable interest entities	0	(92)	0
Net cash used by investing activities	(4,260)	(4,094)	(3,219)
Net decrease in cash and cash equivalents	(200)	(205)	(1,149)
Cash and cash equivalents, beginning of year	257	462	1,611
Cash and cash equivalents, end of year	$ 57	$ 257	$ 462