Offsetting Arrangements - Repo, Sec Lending Transactions Maturity By Category (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	$ 110,960	$ 152,140
Securities lending transactions	17,645	13,653
Gross amount of recognized liabilities for repurchase agreements and securities lending	128,605	165,793
U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	110,960	152,140
Securities lending transactions	2	0
Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	96	110
Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	10,790	8,790
Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	6,757	4,753
Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	110,960	152,140
Securities lending transactions	16,163	12,441
Gross amount of recognized liabilities for repurchase agreements and securities lending	127,123	164,581
Overnight and Continuous | U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	110,960	152,140
Securities lending transactions	2	0
Overnight and Continuous | Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	96	110
Overnight and Continuous | Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	9,308	7,578
Overnight and Continuous | Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	6,757	4,753
Up to 30 Days
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	0
Securities lending transactions	38	56
Gross amount of recognized liabilities for repurchase agreements and securities lending	38	56
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	38	56
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	1,444	1,156
Gross amount of recognized liabilities for repurchase agreements and securities lending	1,444	1,156
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	1,444	1,156
Greater than 90 Days | Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	$ 0	$ 0