Summary of Significant Accounting Policies (Diluted EPS Calculation for Continuing Operations) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income from continuing operations	$ 982	$ 565	$ 531
Less: Net income attributable to non-controlling interests	22	16	14
Net income attributable to the Company	993	855	227
Basic weighted average common shares outstanding	542	540	522
Dilutive weighted average common shares outstanding	551	544	524
Segment, Continuing Operations [Member]
Income from continuing operations	982	565	531
Less: Net income attributable to non-controlling interests	22	16	14
Net income attributable to the Company	960	549	517
Less: Portion attributable to participating securities	6	6	12
Income attributable to common shares	$ 954	$ 543	$ 505
Basic weighted average common shares outstanding	542	540	522
Dilutive effect of potentially issuable common shares	9	4	2
Dilutive weighted average common shares outstanding	551	544	524
Average stock price used to calculate common stock equivalents	$ 29.40	$ 23.76	$ 21.44