Derivative Instruments and Hedging Activities - Offsetting Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Derivative liabilities
Derivative liabilities, gross amount	$ 2,410	$ 1,518
Derivative liabilities, offsetting financial instruments	(441)	(383)
Derivative liabilities, offsetting cash collateral	(409)	(356)
Total derivative liabilities	1,560	779
Derivative liabilities, securities collateral not netted	0	0
Net exposure	1,560	779
Repurchase agreements
Gross amounts	845	668
Repurchase agreements, securities sold, offset	0	0
Repurchase agreements, cash collateral pledged, offset	0	0
Net amounts as recognized	845	668
Repurchase agreements, securities collateral not netted	(845)	(668)
Net exposure	0	0
Derivative, collateral, obligation to return cash	574	862
Derivative, collateral, obligation to return securities	1	1
Derivative, collateral, right to reclaim cash	2,100	1,500
Securities sold under repurchase agreements, fair value of collateral	$ 862	$ 682