Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Other Comprehensive Income:
Tax on foreign currency translation	$ 0	$ 0
Tax on reclassification adjustment for amounts recognized in income	0	0
Defined benefit plans:
Tax on amortization of prior service cost and unrecognized gains and losses included in total benefit cost	4	2
Tax on net actuarial losses	0	0
Tax on deferred derivative gains (losses)	0	0
Tax on reclassification adjustment for amounts recognized in income	0	0
Tax on unrealized investment gains	$ 0	$ 0