Investments in Securities Accumulated Other Comprehensive Income 1 (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
Investments, Debt and Equity Securities [Abstract]
Net unrealized gains (losses) on available-for-sale securities for which we have not recorded other-than-temporary impairment, net of tax	$ 821		$ 1,399
Net unrealized gains (losses) on available-for-sale securities for which we have recorded other-than-temporary impairment, net of tax	778		(465)
Prior service cost and actuarial gains (losses), net of amortization for defined benefit plans, net of tax	(366)		(505)
Other gains (losses)	(29)		(45)
Accumulated other comprehensive income (loss)	$ 1,204	$ 1,038	$ 384