Offsetting Arrangements - Repo, Sec Lending Transactions Maturity By Category (Details) $ in Millions	Dec. 31, 2015 USD ($)
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	$ 37,259
Securities loaned, gross	9,507
Securities sold and securities loaned under agreements to repurchase, gross	46,766
Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	37,157
Securities loaned, gross	8,505
Securities sold and securities loaned under agreements to repurchase, gross	45,662
Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	102
Securities loaned, gross	0
Securities sold and securities loaned under agreements to repurchase, gross	102
30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	0
Securities loaned, gross	1,002
Securities sold and securities loaned under agreements to repurchase, gross	1,002
U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	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	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	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
Non-U.S. sovereign debt
Assets Sold under Agreements to Repurchase [Line Items]
Securities sold under agreements to repurchase, gross	97
Securities loaned, gross	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
Securities loaned, gross	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	97
Securities loaned, gross	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
Securities loaned, gross	0
Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	1
Corporate debt securities | Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	1
Corporate debt securities | Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	0
Corporate debt securities | 30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	0
U.S. equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	9,504
U.S. equity securities | Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	8,502
U.S. equity securities | Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	0
U.S. equity securities | 30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities loaned, gross	$ 1,002