Offsetting Arrangements - Repo, Sec Lending Transactions Maturity By Category (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	$ 53,915	$ 152,140
Securities lending transactions	12,101	13,653
Gross amount of recognized liabilities for repurchase agreements and securities lending	66,016	165,793
U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	53,915	152,140
Securities lending transactions	2	0
Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	149	110
Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	11,949	8,790
Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	1	4,753
Overnight and Continuous
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	53,915	152,140
Securities lending transactions	10,028	12,441
Gross amount of recognized liabilities for repurchase agreements and securities lending	63,943	164,581
Overnight and Continuous | U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	53,915	152,140
Securities lending transactions	2	0
Overnight and Continuous | Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	149	110
Overnight and Continuous | Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	9,876	7,578
Overnight and Continuous | Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	1	4,753
Up to 30 Days
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	0
Securities lending transactions	54	56
Gross amount of recognized liabilities for repurchase agreements and securities lending	54	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	54	56
Up to 30 Days | Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	0	0
30-90 days
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	0
Securities lending transactions	3	0
Gross amount of recognized liabilities for repurchase agreements and securities lending	3	0
30-90 days | U.S. Treasury and agency securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements	0	0
Securities lending transactions	0	0
30-90 days | Corporate debt securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	0	0
30-90 days | Equity securities
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	3
30-90 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	2,016	1,156
Gross amount of recognized liabilities for repurchase agreements and securities lending	2,016	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	2,016	1,156
Greater than 90 Days | Other
Assets Sold under Agreements to Repurchase [Line Items]
Securities lending transactions	$ 0	$ 0