v3.20.4
Employee Benefit Plans (Schedule of Defined Benefit Plans Disclosures) (Details) - USD ($)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Change in Benefit Obligation [Roll Forward]      
Projected Benefit Obligation, Beginning of Period $ 2,364,000,000 $ 2,010,000,000  
Service cost 39,000,000 31,000,000 $ 38,000,000
Interest cost 68,000,000 80,000,000 75,000,000
Actuarial Gains (Losses) 299,000,000 382,000,000  
Defined Benefit Plan, Benefit Obligation, Benefits Paid (144,000,000) (129,000,000)  
Administration Expenses (3,000,000) (3,000,000)  
Plan Settlements 0 (7,000,000)  
Projected Benefit Obligation, End of Period 2,623,000,000 2,364,000,000 2,010,000,000
Change in Plan Assets [Roll Forward]      
Fair Value of Plan Assets, beginning of period 2,299,000,000 2,105,000,000  
Actual Return on Plan Assets (303,000,000) (319,000,000)  
Company Contributions 14,000,000 14,000,000  
Defined Benefit Plan, Plan Assets, Benefits Paid (144,000,000) (129,000,000)  
Administration Expenses (3,000,000) (3,000,000)  
Plan Settlements 0 (7,000,000)  
Fair Value of Plan Assets, end of period 2,469,000,000 2,299,000,000 2,105,000,000
Funded Status and Accrued Benefit Cost at Measurement Date (154,000,000) (65,000,000)  
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) (154,000,000) (65,000,000)  
Pre-tax amounts recognized in Accumulated Other Comprehensive (Income) Loss:      
Net actuarial loss 899,000,000 802,000,000  
Qualified Plan [Member] | Pension Plan [Member]      
Change in Benefit Obligation [Roll Forward]      
Projected Benefit Obligation, Beginning of Period 2,192,000,000 1,865,000,000  
Service cost 34,000,000 28,000,000 35,000,000
Interest cost 64,000,000 75,000,000 70,000,000
Actuarial Gains (Losses) 278,000,000 349,000,000  
Defined Benefit Plan, Benefit Obligation, Benefits Paid (130,000,000) (122,000,000)  
Administration Expenses (3,000,000) (3,000,000)  
Plan Settlements 0 0  
Projected Benefit Obligation, End of Period 2,435,000,000 2,192,000,000 1,865,000,000
Change in Plan Assets [Roll Forward]      
Fair Value of Plan Assets, beginning of period 2,299,000,000 2,105,000,000  
Actual Return on Plan Assets (303,000,000) (319,000,000)  
Company Contributions 0 0  
Defined Benefit Plan, Plan Assets, Benefits Paid (130,000,000) (122,000,000)  
Administration Expenses (3,000,000) (3,000,000)  
Plan Settlements 0 0  
Fair Value of Plan Assets, end of period 2,469,000,000 2,299,000,000 2,105,000,000
Funded Status and Accrued Benefit Cost at Measurement Date 34,000,000 107,000,000  
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) 34,000,000 107,000,000  
Pre-tax amounts recognized in Accumulated Other Comprehensive (Income) Loss:      
Net actuarial loss 819,000,000 736,000,000  
Nonqualified Plan [Member] | Supplemental Employee Retirement Plan [Member]      
Change in Benefit Obligation [Roll Forward]      
Projected Benefit Obligation, Beginning of Period 172,000,000 145,000,000  
Service cost 5,000,000 3,000,000 3,000,000
Interest cost 4,000,000 5,000,000 5,000,000
Actuarial Gains (Losses) 21,000,000 33,000,000  
Defined Benefit Plan, Benefit Obligation, Benefits Paid (14,000,000) (7,000,000)  
Administration Expenses 0 0  
Plan Settlements 0 (7,000,000)  
Projected Benefit Obligation, End of Period 188,000,000 172,000,000 145,000,000
Change in Plan Assets [Roll Forward]      
Fair Value of Plan Assets, beginning of period 0 0  
Actual Return on Plan Assets 0 0  
Company Contributions 14,000,000 14,000,000  
Defined Benefit Plan, Plan Assets, Benefits Paid (14,000,000) (7,000,000)  
Administration Expenses 0 0  
Plan Settlements 0 (7,000,000)  
Fair Value of Plan Assets, end of period 0 0 $ 0
Funded Status and Accrued Benefit Cost at Measurement Date (188,000,000) (172,000,000)  
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) (188,000,000) (172,000,000)  
Pre-tax amounts recognized in Accumulated Other Comprehensive (Income) Loss:      
Net actuarial loss 80,000,000 66,000,000  
Other Assets [Member]      
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) 34,000,000 107,000,000  
Other Assets [Member] | Qualified Plan [Member] | Pension Plan [Member]      
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) 34,000,000 107,000,000  
Other Assets [Member] | Nonqualified Plan [Member] | Supplemental Employee Retirement Plan [Member]      
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) 0 0  
Other Liabilities [Member]      
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) (188,000,000) (172,000,000)  
Other Liabilities [Member] | Qualified Plan [Member] | Pension Plan [Member]      
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) 0 0  
Other Liabilities [Member] | Nonqualified Plan [Member] | Supplemental Employee Retirement Plan [Member]      
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) $ (188,000,000) $ (172,000,000)