Offsetting Arrangements - Repo, Sec Lending Transactions Maturity By Category (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	$ 35,509	$ 37,259
Securities lending transactions	9,424	9,507
Gross amount of recognized liabilities for repurchase agreements and securities lending	44,933	46,766
Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	35,509	37,157
Securities lending transactions	8,390	8,505
Gross amount of recognized liabilities for repurchase agreements and securities lending	43,899	45,662
Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	102
Securities lending transactions	0	0
Gross amount of recognized liabilities for repurchase agreements and securities lending	0	102
30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	0
Securities lending transactions	1,034	1,002
Gross amount of recognized liabilities for repurchase agreements and securities lending	1,034	1,002
U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	35,509	37,162
U.S. Treasury and agency securities | Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	35,509	37,157
U.S. Treasury and agency securities | Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	5
U.S. Treasury and agency securities | 30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	0
Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	53	1
Corporate debt securities | Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	53	1
Corporate debt securities | Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	0	0
Corporate debt securities | 30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	0	0
Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	9,371	9,504
Equity securities | Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	8,337	8,502
Equity securities | Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	0	0
Equity securities | 30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	$ 1,034	1,002
Non-U.S. sovereign debt
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements		97
Securities lending transactions		2
Non-U.S. sovereign debt | Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements		0
Securities lending transactions		2
Non-U.S. sovereign debt | Up to 30 days
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements		97
Securities lending transactions		0
Non-U.S. sovereign debt | 30 – 90 days
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements		0
Securities lending transactions		$ 0