Offsetting Arrangements - Repo, Sec Lending Transactions Maturity By Category (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	$ 156,465	$ 88,904
Securities lending transactions	15,388	15,590
Gross amount of recognized liabilities for repurchase agreements and securities lending	171,853	104,494
U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	156,465	88,904
Securities lending transactions	15	249
Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	354	278
Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	7,519	6,563
Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	7,500	8,500
Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	156,465	88,904
Securities lending transactions	15,258	15,453
Gross amount of recognized liabilities for repurchase agreements and securities lending	171,723	104,357
Overnight and Continuous | U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	156,465	88,904
Securities lending transactions	15	249
Overnight and Continuous | Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	354	278
Overnight and Continuous | Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	7,389	6,426
Overnight and Continuous | Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	7,500	8,500
Up to 30 Days
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	0
Securities lending transactions	0	137
Gross amount of recognized liabilities for repurchase agreements and securities lending	0	137
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	137
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	130	0
Gross amount of recognized liabilities for repurchase agreements and securities lending	130	0
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	130	0
Greater than 90 Days | Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	$ 0	$ 0