Segment Financial Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement [Line Items]
Premiums, revenues - external customers	$ 39,585	$ 36,413	$ 78,523	$ 71,224
Products, revenues - external customers	6,415	6,610	12,544	13,003
Services, revenues - external customers	3,797	3,269	7,231	6,409
Total revenues	50,053	46,485	98,776	91,012
Investment and other income	256	193	478	376
Earnings from operations	3,731	3,203	7,144	6,163
Interest expense	(301)	(271)	(584)	(530)
Earnings before income taxes	3,430	2,932	6,560	5,633
Optum [Member]
Statement [Line Items]
Total revenues	22,671	20,623	43,908	40,307
Investment and other income	92	45	153	87
Earnings from operations	1,520	1,261	2,799	2,367
Interest expense	0	0	0	0
Earnings before income taxes	1,520	1,261	2,799	2,367
External Customers [Member]
Statement [Line Items]
Premiums, revenues - external customers	39,585	36,413	78,523	71,224
Products, revenues - external customers	6,415	6,610	12,544	13,003
Services, revenues - external customers	3,797	3,269	7,231	6,409
Total revenues	49,797	46,292	98,298	90,636
External Customers [Member] | Optum [Member]
Statement [Line Items]
Premiums, revenues - external customers	919	872	1,804	1,720
Products, revenues - external customers	6,415	6,609	12,544	13,002
Services, revenues - external customers	1,839	1,403	3,351	2,747
Total revenues	9,173	8,884	17,699	17,469
Intersegment [Member]
Statement [Line Items]
Total revenues	0	0	0	0
Intersegment [Member] | Optum [Member]
Statement [Line Items]
Total revenues	13,406	11,694	26,056	22,751
Operating Segments [Member] | UnitedHealthcare [Member]
Statement [Line Items]
Total revenues	40,788	37,556	80,924	73,456
Investment and other income	164	148	325	289
Earnings from operations	2,211	1,942	4,345	3,796
Interest expense	0	0	0	0
Earnings before income taxes	2,211	1,942	4,345	3,796
Operating Segments [Member] | OptumHealth [Member]
Statement [Line Items]
Total revenues	5,122	4,065	9,855	8,063
Investment and other income	87	44	143	84
Earnings from operations	422	304	754	604
Interest expense	0	0	0	0
Earnings before income taxes	422	304	754	604
Operating Segments [Member] | OptumInsight [Member]
Statement [Line Items]
Total revenues	1,993	1,762	3,836	3,429
Investment and other income	1	0	2	0
Earnings from operations	372	333	666	579
Interest expense	0	0	0	0
Earnings before income taxes	372	333	666	579
Operating Segments [Member] | OptumRx [Member]
Statement [Line Items]
Total revenues	15,840	15,073	30,787	29,346
Investment and other income	4	1	8	3
Earnings from operations	726	624	1,379	1,184
Interest expense	0	0	0	0
Earnings before income taxes	726	624	1,379	1,184
Operating Segments [Member] | External Customers [Member] | UnitedHealthcare [Member]
Statement [Line Items]
Premiums, revenues - external customers	38,666	35,541	76,719	69,504
Products, revenues - external customers	0	1	0	1
Services, revenues - external customers	1,958	1,866	3,880	3,662
Total revenues	40,624	37,408	80,599	73,167
Operating Segments [Member] | External Customers [Member] | OptumHealth [Member]
Statement [Line Items]
Premiums, revenues - external customers	919	872	1,804	1,720
Products, revenues - external customers	11	11	23	24
Services, revenues - external customers	1,008	597	1,729	1,209
Total revenues	1,938	1,480	3,556	2,953
Operating Segments [Member] | External Customers [Member] | OptumInsight [Member]
Statement [Line Items]
Premiums, revenues - external customers	0	0	0	0
Products, revenues - external customers	19	17	40	37
Services, revenues - external customers	692	639	1,334	1,245
Total revenues	711	656	1,374	1,282
Operating Segments [Member] | External Customers [Member] | OptumRx [Member]
Statement [Line Items]
Premiums, revenues - external customers	0	0	0	0
Products, revenues - external customers	6,385	6,581	12,481	12,941
Services, revenues - external customers	139	167	288	293
Total revenues	6,524	6,748	12,769	13,234
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	3,097	2,541	6,156	5,026
Operating Segments [Member] | Intersegment [Member] | OptumInsight [Member]
Statement [Line Items]
Total revenues	1,281	1,106	2,460	2,147
Operating Segments [Member] | Intersegment [Member] | OptumRx [Member]
Statement [Line Items]
Total revenues	9,312	8,324	18,010	16,109
Optum Eliminations [Member]
Statement [Line Items]
Total revenues	(284)	(277)	(570)	(531)
Investment and other income	0	0	0	0
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
Products, revenues - external customers	0	0	0	0
Services, revenues - external customers	0	0	0	0
Total revenues	0	0	0	0
Optum Eliminations [Member] | Intersegment [Member]
Statement [Line Items]
Total revenues	(284)	(277)	(570)	(531)
Corporate and Eliminations [Member]
Statement [Line Items]
Total revenues	(13,406)	(11,694)	(26,056)	(22,751)
Investment and other income	0	0	0	0
Earnings from operations	0	0	0	0
Interest expense	(301)	(271)	(584)	(530)
Earnings before income taxes	(301)	(271)	(584)	(530)
Corporate and Eliminations [Member] | External Customers [Member]
Statement [Line Items]
Premiums, revenues - external customers	0	0	0	0
Products, revenues - external customers	0	0	0	0
Services, revenues - external customers	0	0	0	0
Total revenues	0	0	0	0
Corporate and Eliminations [Member] | Intersegment [Member]
Statement [Line Items]
Total revenues	$ (13,406)	$ (11,694)	$ (26,056)	$ (22,751)