Consolidated Statements of Cash Flows Statement (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 542	$ 493
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	506	478
Deferred income taxes and amortization of investment tax credits	123	268
Changes in regulatory assets and liabilities	(16)	(27)
Other, net	(27)	(26)
Changes in other operating assets and liabilities:
Accounts receivable and other assets	11	(5)
Derivative collateral, net	43	56
Inventories	(1)	(37)
Income taxes, net	41	159
Accounts payable and other liabilities	75	(4)
Net cash flows from operating activities	1,297	1,355
Cash flows from investing activities:
Capital expenditures	(752)	(1,037)
Other, net	15	0
Net cash flows from investing activities	(737)	(1,037)
Cash flows from financing activities:
Proceeds from long-term debt	299	749
Repayments and redemptions of long-term debt and capital lease obligations	(272)	(91)
Net repayments of short-term debt	0	(688)
Redemption of preferred stock	(5)	0
Common stock dividends	(500)	(150)
Preferred stock dividends	(1)	(2)
Other, net	(4)	(8)
Net cash flows from financing activities	(483)	(190)
Net change in cash and cash equivalents	77	128
Cash and cash equivalents at beginning of period	80	47
Cash and cash equivalents at end of period	$ 157	$ 175