Commitments and Contingencies - Credit Extension Commitments Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Other Commitments [Line Items]
Legally binding unfunded commitments syndicated	$ 13,900	$ 14,300
Carrying amount credit extension commitments syndicated	767	664
Deferred revenue	17	18
Other liabilities reserve for unfunded lending commitments	750	646
Notional amount of credit extension commitments under fair value option	8,100	10,900
Unfunded loan commitments
Other Commitments [Line Items]
Fair value carrying amount liabilities	$ 347	$ 658