Other Comprehensive Income (details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Other Comprehensive Income disclosure
Change in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income, pretax	$ (77)	$ (106)
Change in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income, pretax	25	28
Net changes in benefit plan assets and obligations, pretax	20	18
Net changes in unrealized foreign currency translation and other changes, pretax	64	70
Other comprehensive income before income taxes	32	10
Change in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income, tax expense (benefit)	(27)	(35)
Change in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income, tax expense (benefit)	9	10
Net changes in benefit plan assets and obligations, tax expense (benefit)	7	6
Net changes in unrealized foreign currency translation and other changes, tax expense (benefit)	9	12
Other comprehensive income tax expense (benefit)	(2)	(7)
Change in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income, net of tax	(50)	(71)
Change in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income, net of tax	16	18
Net changes in benefit plan assets and obligations, net of tax	13	12
Net changes in unrealized foreign currency translation and other changes, net of tax	55	58
Other comprehensive income, net of taxes	$ 34	$ 17