Income Taxes (Differences Between The 21 Percent Statutory Income Tax Rate And Effective Income Tax Rate) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Tax at statutory rate:	$ 315	$ 519	$ 53
Tax at statutory rate (percentage):	21.00%	21.00%	21.00%	35.00%
Increase (decrease) resulting from:
Tax-exempt income from municipal bonds	$ (20)	$ (19)	$ (20)
Dividend received exclusion	(17)	(16)	(15)
Effective Income Tax Rate Reconciliation, Tax Accounting Method Changes, Amount	0	0	(50)
Other	5	(9)	(4)
Total provision (benefit) for income taxes	$ 283	$ 475	$ (36)
Tax at statutory rate:
Tax-exempt income from municipal bonds (percentage)	(1.30%)	(0.80%)	(8.00%)
Dividend received exclusion (percentage)	(1.10%)	(0.60%)	(6.00%)
Effective Income Tax Rate Reconciliation, Tax Accounting Method Changes, Percent	0.00%	0.00%	(19.90%)
Deferred tax benefit due to tax rate change			19.90%
Other (percentage)	0.30%	(0.40%)	(1.40%)
Effective tax, percentage	18.90%	19.20%	(14.30%)