Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Cumulative foreign currency translation adjustment	$ 121	$ 136
Pension and postretirement benefits	(609)	(409)
Tax on pension and postretirement benefits	326	220
Net unrealized gains (losses) on investments with OTTI losses	(64)	(73)
Tax on net unrealized gains (losses) on investments with OTTI losses	33	39
Net unrealized gains (losses) on other investments	1,022	691
Tax on net unrealized gains (losses) on other investments	(533)	(348)
Accumulated other comprehensive (income) loss attributable to noncontrolling interests		(19)
Accumulated other comprehensive income (loss)	470	326
Tax on accumulated other comprehensive income (loss)	$ (174)	$ (89)