Employee Benefits - Derivative Instruments (Details) - Combined Pension Plan - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Exchange-traded U.S. equity futures
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	$ 108	$ 84
Exchange-traded Treasury and other interest rate futures
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	1,688	1,033
Exchange-traded Foreign currency futures
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	11	12
Exchange-traded EURO futures
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	5	6
Interest rate swaps
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	127	124
Credit default swaps
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	132	43
Index swaps
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	1,036	1,297
Foreign exchange forwards
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	93	769
Options
Defined Benefit Plan Disclosure [Line Items]
Derivative, notional amount	$ 654	$ 222