Income Taxes(Components Of Deferred Income Taxes) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets relating to:
Retirement benefits	$ 211	$ 226
Accrued expenses	280	301
Insurance reserves	114	96
Net operating loss carryforwards	4	7
Bad debt reserves	82	104
State income tax	11	32
Deferred compensation	22	20
Unrealized losses on securities	0	41
Other	77	72
Total deferred tax assets	801	899
Deferred tax liabilities relating to:
Investments basis difference	78	52
Unrealized gains on securities	153	0
Trademarks and state Medicaid licenses	1,529	1,529
Customer, provider and hospital relationships	239	290
Internally developed software and other amortization differences	528	461
Retirement benefits	194	183
Debt discount	19	27
State deferred tax	77	105
Depreciation and amortization	48	47
Other	163	165
Total deferred tax liabilities	3,028	2,859
Net deferred tax liability	$ 2,227	$ 1,960