Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) - Parenthetical (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Equity [Abstract]
Tax on unrealized gains and losses of derivatives	$ 19	$ (5)	$ 39	$ 24
Tax expense (benefit)	1	2	74	5
Write down on debt securites, tax			0	0
Tax on unrealized holding gains	0	13	0	8
Tax on reclassification adjustment for gains realized in net income	0	(4)	(62)	(4)
Impaired debt securities, tax			0	0
Loss on debt securities, tax			0	0
Tax on reclassification adjustment for gains on net income	0	0	(1)	0
Tax on unfunded pension and postretirment liability	0	0	0		0
Tax on reclassification adjustment	0	0	0		0
Tax on transaction gains (losses)	0	(1)	(1)		0
Tax on translation gain and loss	$ 0	$ 0	$ (9)	$ 0