Investments in Securities Available-for-sale Securities 1 (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]
Gross realized gains	$ 1,066	$ 569	$ 1,632
Gross realized losses	70	5	979
Total proceeds (excludes initial sale of securities from new portfolio securitizations)	$ 8,023	$ 3,265	$ 15,157