Consolidated Statement of Changes in Equity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			$ 9,958	$ 9,207
Net income	214	226	414	462
Other comprehensive income			0	2
Dividends declared on common stock			(233)	(230)
Dividends declared on preferred and preference stock			(41)	(29)
Stock-based compensation and other			(20)	(7)
Noncash stock-based compensation and other			8	8
Issuance of preference stock			805	123
Redemption of preference stock			(75)
Balance	10,816	9,536	10,816	9,536
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			2,168	2,168
Net income			0	0
Other comprehensive income			0	0
Dividends declared on common stock			0	0
Dividends declared on preferred and preference stock			0	0
Stock-based compensation and other			0	0
Noncash stock-based compensation and other			0	0
Issuance of preference stock			0	0
Redemption of preference stock			0
Balance	2,168	2,168	2,168	2,168
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			596	572
Net income			0	0
Other comprehensive income			0	0
Dividends declared on common stock			0	0
Dividends declared on preferred and preference stock			0	0
Stock-based compensation and other			10	3
Noncash stock-based compensation and other			8	8
Issuance of preference stock			(20)	(2)
Redemption of preference stock			1
Balance	595	581	595	581
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			(24)	(25)
Net income			0	0
Other comprehensive income			0	2
Dividends declared on common stock			0	0
Dividends declared on preferred and preference stock			0	0
Stock-based compensation and other			0	0
Noncash stock-based compensation and other			0	0
Issuance of preference stock			0	0
Redemption of preference stock			0
Balance	(24)	(23)	(24)	(23)
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			6,173	5,572
Net income			414	462
Other comprehensive income			0	0
Dividends declared on common stock			(233)	(230)
Dividends declared on preferred and preference stock			(41)	(29)
Stock-based compensation and other			(30)	(10)
Noncash stock-based compensation and other			0	0
Issuance of preference stock			0	0
Redemption of preference stock			(1)
Balance	6,282	5,765	6,282	5,765
Preferred and Preference Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance			1,045	920
Net income			0	0
Other comprehensive income			0	0
Dividends declared on common stock			0	0
Dividends declared on preferred and preference stock			0	0
Stock-based compensation and other			0	0
Noncash stock-based compensation and other			0	0
Issuance of preference stock			825	125
Redemption of preference stock			(75)
Balance	$ 1,795	$ 1,045	$ 1,795	$ 1,045