Consolidations and Transfers of Financial Assets Transfers of Financial Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Transfers of Financial Assets [Line Items]
Portfolio securitizations: unpaid principal balance	$ 64,300	$ 62,000	$ 112,600	$ 110,900
Unconsolidated VIEs [Member]
Transfers of Financial Assets [Line Items]
Principal and interest received on retained interests	315	$ 296	623	$ 646
Unconsolidated VIEs [Member] | Single Class MBS, REMIC & Megas [Member]
Transfers of Financial Assets [Line Items]
Retained interests: unpaid principal balance	5,100		5,100		$ 5,500
Retained interest: fair value	$ 6,900		$ 6,900		$ 6,800