Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues									$ 157,107	$ 130,474	$ 122,489
Operating costs									146,086	120,200	112,866
Earnings from operations									11,021	10,274	9,623
Net earnings									5,868	5,619	5,673
Net earnings attributable to UnitedHealth Group common stockholders									$ 5,813	$ 5,619	$ 5,625
Net earnings per share attributable to UnitedHealth Group common stockholders:
Basic									$ 6.10	$ 5.78	$ 5.59
Diluted									$ 6.01	$ 5.70	$ 5.50
Quarterly Financial Data (Unaudited) [Member]
Revenues	$ 43,599	$ 41,489	$ 36,263	$ 35,756	$ 33,433	$ 32,759	$ 32,574	$ 31,708
Operating costs	41,131	38,471	33,368	33,116	30,668	29,856	30,022	29,654
Earnings from operations	2,468	3,018	2,895	2,640	2,765	2,903	2,552	2,054
Net earnings	1,252	1,618	1,585	1,413	1,510	1,602	1,408	1,099
Net earnings attributable to UnitedHealth Group common stockholders	$ 1,218	$ 1,597	$ 1,585	$ 1,413	$ 1,510	$ 1,602	$ 1,408	$ 1,099
Net earnings per share attributable to UnitedHealth Group common stockholders:
Basic	$ 1.28	$ 1.68	$ 1.66	$ 1.48	$ 1.58	$ 1.65	$ 1.44	$ 1.12
Diluted	$ 1.26	$ 1.65	$ 1.64	$ 1.46	$ 1.55	$ 1.63	$ 1.42	$ 1.10