Income Taxes (Reconciliation Of Income Tax Expense Computed At The Statutory Federal Income Tax Rate) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Amount at statutory rate, amount	$ 1,310	$ 1,257	$ 1,064
Amount at statutory rate, percent	21.00%	21.00%	21.00%
State and local income taxes net of federal tax expense/benefit, amount	$ 235	$ 138	$ 63
State and local income taxes net of federal tax expense/benefit, percent	3.80%	2.30%	1.20%
Tax exempt interest and dividends received deduction, amount	$ (22)	$ (24)	$ (27)
Tax exempt interest and dividends received deduction, percent	(0.40%)	(0.40%)	(0.50%)
Health Insurance Provider fee, amount	$ 330	$ 0	$ 324
Health Insurance Provider fee, percent	5.30%	0.00%	6.40%
Basis adjustments from recent acquisitions, amount	$ (110)	$ 0	$ (28)
Basis adjustments from recent acquisitions, percent	(1.80%)	0.00%	(0.60%)
Tax Cuts and Jobs Act, amount	$ 0	$ 0	$ (28)
Tax Cuts and Jobs Act, percent	0.00%	0.00%	(0.60%)
Other, net amount	$ (77)	$ (193)	$ (50)
Other, net percent	(1.20%)	(3.20%)	(0.90%)
Total income tax expense	$ 1,666	$ 1,178	$ 1,318
Total income tax expense, percent	26.70%	19.70%	26.00%