v3.19.3.a.u2
Employee Benefit Plans (Schedule of Defined Benefit Plans Disclosures) (Details) - USD ($)
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Change in Benefit Obligation [Roll Forward]      
Projected Benefit Obligation, Beginning of Period $ 2,010,000,000 $ 2,285,000,000  
Service cost 31,000,000 38,000,000 $ 38,000,000
Interest cost 80,000,000 75,000,000 77,000,000
Actuarial Gains (Losses) 382,000,000 (214,000,000)  
Defined Benefit Plan, Benefit Obligation, Benefits Paid (129,000,000) (170,000,000)  
Administration Expenses (3,000,000) (4,000,000)  
Plan Settlements (7,000,000) 0  
Projected Benefit Obligation, End of Period 2,364,000,000 2,010,000,000 2,285,000,000
Change in Plan Assets [Roll Forward]      
Fair Value of Plan Assets, beginning of period 2,105,000,000 2,218,000,000  
Actual Return on Plan Assets (319,000,000) 50,000,000  
Company Contributions 14,000,000 111,000,000  
Defined Benefit Plan, Plan Assets, Benefits Paid (129,000,000) (170,000,000)  
Administration Expenses (3,000,000) (4,000,000)  
Plan Settlements (7,000,000) 0  
Fair Value of Plan Assets, end of period 2,299,000,000 2,105,000,000 2,218,000,000
Funded Status and Accrued Benefit Cost at Measurement Date (65,000,000) 95,000,000  
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) (65,000,000) 95,000,000  
Pre-tax amounts recognized in Accumulated Other Comprehensive (Income) Loss:      
Net actuarial loss 802,000,000 643,000,000  
Prior service cost (credit) 0 1,000,000  
Total amounts recognized in Accumulated Other Comprehensive Income (Loss) 802,000,000 644,000,000  
Qualified Plan [Member] | Pension Plan [Member]      
Change in Benefit Obligation [Roll Forward]      
Projected Benefit Obligation, Beginning of Period 1,865,000,000 2,134,000,000  
Service cost 28,000,000 35,000,000 34,000,000
Interest cost 75,000,000 70,000,000 72,000,000
Actuarial Gains (Losses) 349,000,000 (211,000,000)  
Defined Benefit Plan, Benefit Obligation, Benefits Paid (122,000,000) (159,000,000)  
Administration Expenses (3,000,000) (4,000,000)  
Plan Settlements 0 0  
Projected Benefit Obligation, End of Period 2,192,000,000 1,865,000,000 2,134,000,000
Change in Plan Assets [Roll Forward]      
Fair Value of Plan Assets, beginning of period 2,105,000,000 2,218,000,000  
Actual Return on Plan Assets (319,000,000) 50,000,000  
Company Contributions 0 100,000,000  
Defined Benefit Plan, Plan Assets, Benefits Paid (122,000,000) (159,000,000)  
Administration Expenses (3,000,000) (4,000,000)  
Plan Settlements 0 0  
Fair Value of Plan Assets, end of period 2,299,000,000 2,105,000,000 2,218,000,000
Funded Status and Accrued Benefit Cost at Measurement Date 107,000,000 240,000,000  
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) 107,000,000 240,000,000  
Pre-tax amounts recognized in Accumulated Other Comprehensive (Income) Loss:      
Net actuarial loss 736,000,000 604,000,000  
Prior service cost (credit) 0 0  
Total amounts recognized in Accumulated Other Comprehensive Income (Loss) 736,000,000 604,000,000  
Nonqualified Plan [Member] | Supplemental Employee Retirement Plan [Member]      
Change in Benefit Obligation [Roll Forward]      
Projected Benefit Obligation, Beginning of Period 145,000,000 151,000,000  
Service cost 3,000,000 3,000,000 4,000,000
Interest cost 5,000,000 5,000,000 5,000,000
Actuarial Gains (Losses) 33,000,000 (3,000,000)  
Defined Benefit Plan, Benefit Obligation, Benefits Paid (7,000,000) (11,000,000)  
Administration Expenses 0 0  
Plan Settlements (7,000,000) 0  
Projected Benefit Obligation, End of Period 172,000,000 145,000,000 151,000,000
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 11,000,000  
Defined Benefit Plan, Plan Assets, Benefits Paid (7,000,000) (11,000,000)  
Administration Expenses 0 0  
Plan Settlements (7,000,000) 0  
Fair Value of Plan Assets, end of period 0 0 $ 0
Funded Status and Accrued Benefit Cost at Measurement Date (172,000,000) (145,000,000)  
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) (172,000,000) (145,000,000)  
Pre-tax amounts recognized in Accumulated Other Comprehensive (Income) Loss:      
Net actuarial loss 66,000,000 39,000,000  
Prior service cost (credit) 0 1,000,000  
Total amounts recognized in Accumulated Other Comprehensive Income (Loss) 66,000,000 40,000,000  
Other Assets [Member]      
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) 107,000,000 240,000,000  
Other Assets [Member] | Qualified Plan [Member] | Pension Plan [Member]      
Amount recognized in the Consolidated Balance Sheets:      
Other assets (liabilities) 107,000,000 240,000,000  
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) (172,000,000) (145,000,000)  
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) $ (172,000,000) $ (145,000,000)