Consolidated Statements of Comprehensive Income (Parenthetical) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income tax effect - unrecognized amounts on retirement benefits	$ (28)	$ (10)	$ 29
Income tax effect - unrealized gains (losses) on available-for-sale securities	79	(279)	(318)
Income tax effect - unrealized gains (losses) on cash flow hedges	$ 5	$ (5)	$ 15