Segment Financial Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement [Line Items]
Premiums, revenues - external customers	$ 31,961	$ 28,840	$ 63,635	$ 56,955
Services, revenues - external customers	2,865	2,447	5,571	4,851
Products, revenues - external customers	1,223	1,037	2,453	2,035
Investment and other income	214	250	360	441
Total revenues	36,263	32,574	72,019	64,282
Earnings from operations	2,895	2,552	5,535	4,606
Interest expense	(151)	(155)	(301)	(315)
Earnings before income taxes	2,744	2,397	5,234	4,291
Optum [Member]
Statement [Line Items]
Investment and other income	43	39	74	74
Total revenues	13,588	11,714	26,403	22,884
Earnings from operations	864	728	1,606	1,378
Interest expense	0	0	0	0
Earnings before income taxes	864	728	1,606	1,378
External Customers [Member]
Statement [Line Items]
Premiums, revenues - external customers	31,961	28,840	63,635	56,955
Services, revenues - external customers	2,865	2,447	5,571	4,851
Products, revenues - external customers	1,223	1,037	2,453	2,035
Total revenues	36,049	32,324	71,659	63,841
External Customers [Member] | Optum [Member]
Statement [Line Items]
Premiums, revenues - external customers	775	627	1,544	1,231
Services, revenues - external customers	1,150	801	2,253	1,619
Products, revenues - external customers	1,222	1,036	2,452	2,033
Total revenues	3,147	2,464	6,249	4,883
Intersegment [Member]
Statement [Line Items]
Total revenues	0	0	0	0
Intersegment [Member] | Optum [Member]
Statement [Line Items]
Total revenues	10,398	9,211	20,080	17,927
Operating Segments [Member] | UnitedHealthcare [Member]
Statement [Line Items]
Investment and other income	171	211	286	367
Total revenues	33,073	30,071	65,696	59,325
Earnings from operations	2,031	1,824	3,929	3,228
Interest expense	0	0	0	0
Earnings before income taxes	2,031	1,824	3,929	3,228
Operating Segments [Member] | Optumhealth [Member]
Statement [Line Items]
Investment and other income	42	39	73	74
Total revenues	3,438	2,586	6,727	5,166
Earnings from operations	253	224	487	435
Interest expense	0	0	0	0
Earnings before income taxes	253	224	487	435
Operating Segments [Member] | Optuminsight [Member]
Statement [Line Items]
Investment and other income	0	0	0	0
Total revenues	1,409	1,243	2,799	2,490
Earnings from operations	271	213	493	410
Interest expense	0	0	0	0
Earnings before income taxes	271	213	493	410
Operating Segments [Member] | Optumrx [Member]
Statement [Line Items]
Investment and other income	1	0	1	0
Total revenues	8,913	8,000	17,208	15,458
Earnings from operations	340	291	626	533
Interest expense	0	0	0	0
Earnings before income taxes	340	291	626	533
Operating Segments [Member] | External Customers [Member] | UnitedHealthcare [Member]
Statement [Line Items]
Premiums, revenues - external customers	31,186	28,213	62,091	55,724
Services, revenues - external customers	1,715	1,646	3,318	3,232
Products, revenues - external customers	1	1	1	2
Total revenues	32,902	29,860	65,410	58,958
Operating Segments [Member] | External Customers [Member] | Optumhealth [Member]
Statement [Line Items]
Premiums, revenues - external customers	775	627	1,544	1,231
Services, revenues - external customers	579	242	1,100	505
Products, revenues - external customers	11	4	16	11
Total revenues	1,365	873	2,660	1,747
Operating Segments [Member] | External Customers [Member] | Optuminsight [Member]
Statement [Line Items]
Premiums, revenues - external customers	0	0	0	0
Services, revenues - external customers	542	532	1,101	1,057
Products, revenues - external customers	16	14	36	40
Total revenues	558	546	1,137	1,097
Operating Segments [Member] | External Customers [Member] | Optumrx [Member]
Statement [Line Items]
Premiums, revenues - external customers	0	0	0	0
Services, revenues - external customers	29	27	52	57
Products, revenues - external customers	1,195	1,018	2,400	1,982
Total revenues	1,224	1,045	2,452	2,039
Operating Segments [Member] | Intersegment [Member] | UnitedHealthcare [Member]
Statement [Line Items]
Total revenues	0	0	0	0
Operating Segments [Member] | Intersegment [Member] | Optumhealth [Member]
Statement [Line Items]
Total revenues	2,031	1,674	3,994	3,345
Operating Segments [Member] | Intersegment [Member] | Optuminsight [Member]
Statement [Line Items]
Total revenues	851	697	1,662	1,393
Operating Segments [Member] | Intersegment [Member] | Optumrx [Member]
Statement [Line Items]
Total revenues	7,688	6,955	14,755	13,419
Optum Eliminations [Member]
Statement [Line Items]
Investment and other income	0	0	0	0
Total revenues	(172)	(115)	(331)	(230)
Earnings from operations	0	0	0	0
Interest expense	0	0	0	0
Earnings before income taxes	0	0	0	0
Optum Eliminations [Member] | External Customers [Member]
Statement [Line Items]
Premiums, revenues - external customers	0	0	0	0
Services, revenues - external customers	0	0	0	0
Products, revenues - external customers	0	0	0	0
Total revenues	0	0	0	0
Optum Eliminations [Member] | Intersegment [Member]
Statement [Line Items]
Total revenues	(172)	(115)	(331)	(230)
Corporate and Eliminations [Member]
Statement [Line Items]
Investment and other income	0	0	0	0
Total revenues	(10,398)	(9,211)	(20,080)	(17,927)
Earnings from operations	0	0	0	0
Interest expense	(151)	(155)	(301)	(315)
Earnings before income taxes	(151)	(155)	(301)	(315)
Corporate and Eliminations [Member] | External Customers [Member]
Statement [Line Items]
Premiums, revenues - external customers	0	0	0	0
Services, revenues - external customers	0	0	0	0
Products, revenues - external customers	0	0	0	0
Total revenues	0	0	0	0
Corporate and Eliminations [Member] | Intersegment [Member]
Statement [Line Items]
Total revenues	$ (10,398)	$ (9,211)	$ (20,080)	$ (17,927)