Offsetting Arrangements - Repo, Sec Lending Transactions Maturity By Category (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	$ 35,471	$ 37,259
Securities loaned, gross	10,892	9,507
Securities sold and securities loaned under agreements to repurchase, gross	46,363	46,766
Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	35,399	37,157
Securities loaned, gross	9,998	8,505
Securities sold and securities loaned under agreements to repurchase, gross	45,397	45,662
Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	72	102
Securities loaned, gross	0	0
Securities sold and securities loaned under agreements to repurchase, gross	72	102
30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	0	0
Securities loaned, gross	894	1,002
Securities sold and securities loaned under agreements to repurchase, gross	894	1,002
U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	35,414	37,162
U.S. Treasury and agency securities | Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	35,399	37,157
U.S. Treasury and agency securities | Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	15	5
U.S. Treasury and agency securities | 30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	0	0
Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	63	1
Corporate debt securities | Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	63	1
Corporate debt securities | Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	0	0
Corporate debt securities | 30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	0	0
Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	10,420	9,504
Equity securities | Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	9,526	8,502
Equity securities | Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	0	0
Equity securities | 30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	894	1,002
Non-U.S. sovereign debt
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	57	97
Securities loaned, gross	409	2
Non-U.S. sovereign debt | Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	0	0
Securities loaned, gross	409	2
Non-U.S. sovereign debt | Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	57	97
Securities loaned, gross	0	0
Non-U.S. sovereign debt | 30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	0	0
Securities loaned, gross	$ 0	$ 0