Consolidated Statements of Cash Flows Statement (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 326	$ 281
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	337	317
Deferred income taxes and amortization of investment tax credits	78	170
Changes in regulatory assets and liabilities	(7)	(4)
Other, net	(20)	(18)
Changes in other operating assets and liabilities:
Accounts receivable and other assets	69	54
Derivative collateral, net	23	13
Inventories	(19)	(37)
Income taxes, net	(11)	130
Accounts payable and other liabilities	55	(24)
Net cash flows from operating activities	831	882
Cash flows from investing activities:
Capital expenditures	(518)	(721)
Other, net	6	(13)
Net cash flows from investing activities	(512)	(734)
Cash flows from financing activities:
Net repayments of short-term debt	0	(688)
Proceeds from long-term debt	299	749
Repayments and redemptions of long-term debt and capital lease obligations	(71)	(90)
Redemption of Preferred Stock	(5)	0
Common stock dividends	(500)	(50)
Preferred stock dividends	(1)	(1)
Other, net	(2)	(8)
Net cash flows from financing activities	(280)	(88)
Net change in cash and cash equivalents	39	60
Cash and cash equivalents at beginning of period	80	47
Cash and cash equivalents at end of period	$ 119	$ 107