Segment Financial Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement [Line Items]
Premiums, revenues - external customers	$ 36,142	$ 31,801	$ 107,366	$ 95,436
Products, revenues - external customers	6,696	6,482	19,699	8,935
Services, revenues - external customers	3,264	3,036	9,673	8,607
Investment and other income	191	170	567	530
Total revenues	46,293	41,489	137,305	113,508
Earnings from operations	3,580	3,018	9,743	8,553
Interest expense	(269)	(229)	(799)	(530)
Earnings before income taxes	3,311	2,789	8,944	8,023
Optum [Member]
Statement [Line Items]
Investment and other income	58	41	145	115
Total revenues	21,119	19,302	61,426	45,705
Earnings from operations	1,467	1,142	3,834	2,748
Interest expense	0	0	0	0
Earnings before income taxes	1,467	1,142	3,834	2,748
External Customers [Member]
Statement [Line Items]
Premiums, revenues - external customers	36,142	31,801	107,366	95,436
Products, revenues - external customers	6,696	6,482	19,699	8,935
Services, revenues - external customers	3,264	3,036	9,673	8,607
Total revenues	46,102	41,319	136,738	112,978
External Customers [Member] | Optum [Member]
Statement [Line Items]
Premiums, revenues - external customers	1,005	823	2,725	2,367
Products, revenues - external customers	6,696	6,482	19,698	8,934
Services, revenues - external customers	1,357	1,326	4,104	3,579
Total revenues	9,058	8,631	26,527	14,880
Intersegment [Member]
Statement [Line Items]
Total revenues	0	0	0	0
Intersegment [Member] | Optum [Member]
Statement [Line Items]
Total revenues	12,003	10,630	34,754	30,710
Operating Segments [Member] | UnitedHealthcare [Member]
Statement [Line Items]
Investment and other income	133	129	422	415
Total revenues	37,177	32,817	110,633	98,513
Earnings from operations	2,113	1,876	5,909	5,805
Interest expense	0	0	0	0
Earnings before income taxes	2,113	1,876	5,909	5,805
Operating Segments [Member] | Optumhealth [Member]
Statement [Line Items]
Investment and other income	55	40	139	113
Total revenues	4,332	3,532	12,395	10,259
Earnings from operations	404	363	1,008	850
Interest expense	0	0	0	0
Earnings before income taxes	404	363	1,008	850
Operating Segments [Member] | Optuminsight [Member]
Statement [Line Items]
Investment and other income	1	1	1	1
Total revenues	1,825	1,585	5,254	4,384
Earnings from operations	371	289	950	782
Interest expense	0	0	0	0
Earnings before income taxes	371	289	950	782
Operating Segments [Member] | Optumrx [Member]
Statement [Line Items]
Investment and other income	2	0	5	1
Total revenues	15,237	14,407	44,583	31,615
Earnings from operations	692	490	1,876	1,116
Interest expense	0	0	0	0
Earnings before income taxes	692	490	1,876	1,116
Operating Segments [Member] | External Customers [Member] | UnitedHealthcare [Member]
Statement [Line Items]
Premiums, revenues - external customers	35,137	30,978	104,641	93,069
Products, revenues - external customers	0	0	1	1
Services, revenues - external customers	1,907	1,710	5,569	5,028
Total revenues	37,044	32,688	110,211	98,098
Operating Segments [Member] | External Customers [Member] | Optumhealth [Member]
Statement [Line Items]
Premiums, revenues - external customers	1,005	823	2,725	2,367
Products, revenues - external customers	12	8	36	24
Services, revenues - external customers	604	594	1,813	1,694
Total revenues	1,621	1,425	4,574	4,085
Operating Segments [Member] | External Customers [Member] | Optuminsight [Member]
Statement [Line Items]
Premiums, revenues - external customers	0	0	0	0
Products, revenues - external customers	30	31	67	67
Services, revenues - external customers	617	592	1,862	1,693
Total revenues	647	623	1,929	1,760
Operating Segments [Member] | External Customers [Member] | Optumrx [Member]
Statement [Line Items]
Premiums, revenues - external customers	0	0	0	0
Products, revenues - external customers	6,654	6,443	19,595	8,843
Services, revenues - external customers	136	140	429	192
Total revenues	6,790	6,583	20,024	9,035
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	2,656	2,067	7,682	6,061
Operating Segments [Member] | Intersegment [Member] | Optuminsight [Member]
Statement [Line Items]
Total revenues	1,177	961	3,324	2,623
Operating Segments [Member] | Intersegment [Member] | Optumrx [Member]
Statement [Line Items]
Total revenues	8,445	7,824	24,554	22,579
Optum Eliminations [Member]
Statement [Line Items]
Investment and other income	0	0	0	0
Total revenues	(275)	(222)	(806)	(553)
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	(275)	(222)	(806)	(553)
Corporate and Eliminations [Member]
Statement [Line Items]
Investment and other income	0	0	0	0
Total revenues	(12,003)	(10,630)	(34,754)	(30,710)
Earnings from operations	0	0	0	0
Interest expense	(269)	(229)	(799)	(530)
Earnings before income taxes	(269)	(229)	(799)	(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	$ (12,003)	$ (10,630)	$ (34,754)	$ (30,710)