Employee Benefit Plans - Schedule of Allocation of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Amount	$ 3,016	$ 3,000
Percent of Total Assets	100.00%	100.00%
Growth-Oriented
Defined Benefit Plan Disclosure [Line Items]
Amount	$ 1,812	$ 1,816
Percent of Total Assets	60.00%	61.00%
Equity
Defined Benefit Plan Disclosure [Line Items]
Amount	$ 1,559	$ 1,324
Percent of Total Assets	52.00%	44.00%
Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Amount	$ 204	$ 271
Percent of Total Assets	7.00%	9.00%
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Amount	$ 49	$ 221
Percent of Total Assets	1.00%	8.00%
Immunizing
Defined Benefit Plan Disclosure [Line Items]
Amount	$ 1,204	$ 1,184
Percent of Total Assets	40.00%	39.00%
Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Amount	$ 1,145	$ 1,018
Percent of Total Assets	38.00%	34.00%
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Amount	$ 59	$ 166
Percent of Total Assets	2.00%	5.00%