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, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Medical Claims Payable [Line Items]
Gross medical claims payable, beginning of period		$ 11,135		$ 8,647	$ 11,135	$ 8,647
Ceded medical claims payable, beginning of period		(46)		(33)	(46)	(33)
Net medical claims payable, beginning of period		11,089		8,614	11,089	8,614
Business combinations and purchase adjustments	$ 420		$ 339		420	339
Current period net incurred medical claims					48,343	39,978
Prior periods redundancies					(1,772)	(700)
Total net incurred medical claims	23,844	22,727	18,748	20,530	46,571	39,278
Net payments attributable to current period medical claims					37,533	31,625
Net payments attributable to prior periods medical claims					7,767	7,041
Total net payments					45,300	38,666
Net medical claims payable, end of period	12,780		9,565		12,780	9,565
Ceded medical claims payable, end of period	41		90		41	90
Gross medical claims payable, end of period	12,821		9,655		12,821	9,655
Commercial Specialty Business Segment [Member]
Medical Claims Payable [Line Items]
Gross medical claims payable, beginning of period		3,294		3,039	3,294	3,039
Ceded medical claims payable, beginning of period		(13)		(14)	(13)	(14)
Net medical claims payable, beginning of period		3,281		3,025	3,281	3,025
Business combinations and purchase adjustments	0		0		0	0
Current period net incurred medical claims					13,360	11,318
Prior periods redundancies					(570)	(374)
Total net incurred medical claims	6,718	6,072	5,147	5,797	12,790	10,944
Net payments attributable to current period medical claims					10,295	9,014
Net payments attributable to prior periods medical claims					2,154	2,218
Total net payments					12,449	11,232
Net medical claims payable, end of period	3,622		2,737		3,622	2,737
Ceded medical claims payable, end of period	11		62		11	62
Gross medical claims payable, end of period	3,633		2,799		3,633	2,799
Government Business Segment [Member]
Medical Claims Payable [Line Items]
Gross medical claims payable, beginning of period		7,646		5,608	7,646	5,608
Ceded medical claims payable, beginning of period		(33)		(19)	(33)	(19)
Net medical claims payable, beginning of period		7,613		5,589	7,613	5,589
Business combinations and purchase adjustments	375		141		375	141
Current period net incurred medical claims					34,232	28,162
Prior periods redundancies					(1,190)	(326)
Total net incurred medical claims	16,723	16,319	13,233	14,603	33,042	27,836
Net payments attributable to current period medical claims					26,647	22,115
Net payments attributable to prior periods medical claims					5,455	4,823
Total net payments					32,102	26,938
Net medical claims payable, end of period	8,928		6,628		8,928	6,628
Ceded medical claims payable, end of period	30		28		30	28
Gross medical claims payable, end of period	8,958		6,656		8,958	6,656
Other Segment [Member]
Medical Claims Payable [Line Items]
Gross medical claims payable, beginning of period		195		0	195	0
Ceded medical claims payable, beginning of period		0		0	0	0
Net medical claims payable, beginning of period		195		0	195	0
Business combinations and purchase adjustments	45		198		45	198
Current period net incurred medical claims					751	498
Prior periods redundancies					(12)	0
Total net incurred medical claims	403	$ 336	368	$ 130	739	498
Net payments attributable to current period medical claims					591	496
Net payments attributable to prior periods medical claims					158	0
Total net payments					749	496
Net medical claims payable, end of period	230		200		230	200
Ceded medical claims payable, end of period	0		0		0	0
Gross medical claims payable, end of period	$ 230		$ 200		$ 230	$ 200