Commitments and Guarantees - Contractual Amounts of Credit-Related Off-Balance Sheet Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Unfunded commitments to extend credit	$ 27,165	$ 26,993
Indemnified securities financing	373,533	360,452
Stable value protection	26,020	27,182
Standby letters of credit	$ 3,440	$ 3,459