WAC, WALA, WAM (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Transfers of Financial Assets [Line Items]
Unpaid principal balance portfolio securitizations	$ 62,000	$ 36,400	$ 110,900	$ 68,900
Unconsolidated VIEs [Member]
Transfers of Financial Assets [Line Items]
Principal and interest received on retained interests	296	$ 373	646	$ 713
Unconsolidated VIEs [Member] | Single Class MBS, REMIC & Megas [Member]
Transfers of Financial Assets [Line Items]
Unpaid principal balance of retained interests	5,500		5,500		$ 6,300
Fair value of retained interests	$ 7,100		$ 7,100		$ 7,600