Employment Benefit Plans Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Equity securities exceeding 10 percent of plan assets	four	three
Percent of total assets that equity securities exceeding 10 percent of plan assets represent	10.00%	10.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	78.00%	67.00%
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	$ 3,170	$ 2,916	$ 2,672
Pension Benefits | Level 1 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	3,157	2,889
Pension Benefits | Level 2 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	13	27
Pension Benefits | Level 3 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	0
Pension Benefits | Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	9	19
Pension Benefits | Cash and equivalents | Level 1 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	1	1
Pension Benefits | Cash and equivalents | Level 2 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	8	18
Pension Benefits | Cash and equivalents | Level 3 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	0
Pension Benefits | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	2,900	2,634
Pension Benefits | Equity Securities | Level 1 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	2,900	2,634
Pension Benefits | Equity Securities | Level 2 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	0
Pension Benefits | Equity Securities | Level 3 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	0
Pension Benefits | Government obligations
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	256	254
Pension Benefits | Government obligations | Level 1 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	256	254
Pension Benefits | Government obligations | Level 2 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	0
Pension Benefits | Government obligations | Level 3 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	0
Pension Benefits | Other fixed maturity securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	5	9
Pension Benefits | Other fixed maturity securities | Level 1 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	0	0
Pension Benefits | Other fixed maturity securities | Level 2 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	5	9
Pension Benefits | Other fixed maturity securities | Level 3 Inputs
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Accrued Dividend And Interest Receivable	$ 0	$ 0