Commitments and Guarantees - Contractual Amounts of Credit-Related Off-Balance Sheet Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Unfunded commitments to extend credit	$ 28,154	$ 26,570
Indemnified securities financing	360,452	320,436
Stable value protection	27,182	24,583
Standby letters of credit	$ 3,459	$ 4,700