Medical Claims Payable (Reconciliation Of The Beginning And Ending Balances For Medical Claims Payable By Segment) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Medical Claims Payable [Line Items]
Gross medical claims payable, beginning of period			$ 7,266	$ 7,814
Ceded medical claims payable, beginning of period			(34)	(105)
Net medical claims payable, beginning of period			7,232	7,709
Liability For Unpaid Claims And Claims Adjustment Expense Purchase Adjustments		$ 199		199
Current period net incurred medical claims			38,237	33,922
Prior periods redundancies			(414)	(795)
Total net incurred medical claims	$ 19,484	16,923	37,823	33,127
Net payments attributable to current period medical claims			30,367	27,502
Net payments attributable to prior periods medical claims			6,182	6,208
Total net payments			36,549	33,710
Short duration contract liability for unpaid claims and adjustment expense, Net	8,506	7,325	8,506	7,325
Ceded medical claims payable, end of period	43	35	43	35
Gross medical claims payable, end of period	8,549	7,360	8,549	7,360
Government Business Segment [Member]
Medical Claims Payable [Line Items]
Gross medical claims payable, beginning of period			4,680	4,431
Ceded medical claims payable, beginning of period			(24)	(27)
Net medical claims payable, beginning of period			4,656	4,404
Liability For Unpaid Claims And Claims Adjustment Expense Purchase Adjustments		199		199
Current period net incurred medical claims			25,777	22,223
Prior periods redundancies			(232)	(390)
Total net incurred medical claims	12,704	11,039	25,545	21,833
Net payments attributable to current period medical claims			20,439	18,135
Net payments attributable to prior periods medical claims			4,101	3,688
Total net payments			24,540	21,823
Short duration contract liability for unpaid claims and adjustment expense, Net	5,661	4,613	5,661	4,613
Ceded medical claims payable, end of period	29	31	29	31
Gross medical claims payable, end of period	5,690	4,644	5,690	4,644
Commercial Specialty Business Segment [Member]
Medical Claims Payable [Line Items]
Gross medical claims payable, beginning of period			2,586	3,383
Ceded medical claims payable, beginning of period			(10)	(78)
Net medical claims payable, beginning of period			2,576	3,305
Liability For Unpaid Claims And Claims Adjustment Expense Purchase Adjustments		0		0
Current period net incurred medical claims			12,460	11,699
Prior periods redundancies			(182)	(405)
Total net incurred medical claims	6,780	5,884	12,278	11,294
Net payments attributable to current period medical claims			9,928	9,367
Net payments attributable to prior periods medical claims			2,081	2,520
Total net payments			12,009	11,887
Short duration contract liability for unpaid claims and adjustment expense, Net	2,845	2,712	2,845	2,712
Ceded medical claims payable, end of period	14	4	14	4
Gross medical claims payable, end of period	$ 2,859	$ 2,716	$ 2,859	$ 2,716