Offsetting Arrangements - Repo, Sec Lending Transactions Maturity By Category (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	$ 170,595	$ 156,465
Securities lending transactions	10,530	15,388
Gross amount of recognized liabilities for repurchase agreements and securities lending	181,125	171,853
U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	170,595	156,465
Securities lending transactions	418	15
Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	167	354
Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	5,445	7,519
Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	4,500	7,500
Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	170,595	156,465
Securities lending transactions	10,377	15,258
Gross amount of recognized liabilities for repurchase agreements and securities lending	180,972	171,723
Overnight and Continuous | U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	170,595	156,465
Securities lending transactions	418	15
Overnight and Continuous | Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	167	354
Overnight and Continuous | Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	5,292	7,389
Overnight and Continuous | Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	4,500	7,500
Up to 30 Days
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	0
Securities lending transactions	0	0
Gross amount of recognized liabilities for repurchase agreements and securities lending	0	0
Up to 30 Days | U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	0
Securities lending transactions	0	0
Up to 30 Days | Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	0	0
Up to 30 Days | Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	0	0
Up to 30 Days | Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	0	0
Greater than 90 Days
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	0
Securities lending transactions	153	130
Gross amount of recognized liabilities for repurchase agreements and securities lending	153	130
Greater than 90 Days | U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	0
Securities lending transactions	0	0
Greater than 90 Days | Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	0	0
Greater than 90 Days | Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	153	130
Greater than 90 Days | Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	$ 0	$ 0