Consolidated Statements of Changes in Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Net Unrealized Gains (Losses) on Investments [Member]	Foreign Currency Translation (Losses) Gains [Member]	Nonredeemable noncontrolling interests [Member]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 28			$ 28
Balance at Dec. 31, 2015	33,725	$ 10	$ 29	37,125	$ 56	$ (3,390)	$ (105)
Balance (in shares) at Dec. 31, 2015		953
Net earnings attributable to UnitedHealth Group common shareholders	7,017			7,017
Net earnings attributable to nonredeemable noncontrolling interest							40
Net earnings, Including Portion Attributable to Nonredeemable Noncontrolling Interest	7,057
Other comprehensive (loss) income	653				(153)	806
Issuances of common stock, and related tax effects (in shares)		9
Issuances of common stock, and related tax effects	191	$ 0	191
Share-based compensation	455		455
Common share repurchases (in shares)		(10)
Common share repurchases	(1,280)	$ 0	(316)	(964)
Cash dividends paid on common shares ($3.45 per share, $2.875 per share and $2.375 per share for years ended December 31, 2018, December 31, 2017 and December 31, 2016, respectively)	(2,261)			(2,261)
Acquisition of redeemable noncontrolling interest shares	(143)		(143)
Redeemable noncontrolling interests fair value and other adjustments	(216)		(216)
Distributions to nonredeemable noncontrolling interests	(32)						(32)
Balance at Dec. 31, 2016	38,177	$ 10	0	40,945	(97)	(2,584)	(97)
Balance (in shares) at Dec. 31, 2016		952
Net earnings attributable to UnitedHealth Group common shareholders	10,558			10,558
Net earnings attributable to nonredeemable noncontrolling interest							194
Net earnings, Including Portion Attributable to Nonredeemable Noncontrolling Interest	10,752
Other comprehensive (loss) income	14				84	(70)
Issuances of common stock, and related tax effects (in shares)		26
Issuances of common stock, and related tax effects	2,225	$ 0	2,225
Share-based compensation	$ 582		582
Common share repurchases (in shares)	(9)	(9)
Common share repurchases	$ (1,500)	$ 0	(1,500)
Cash dividends paid on common shares ($3.45 per share, $2.875 per share and $2.375 per share for years ended December 31, 2018, December 31, 2017 and December 31, 2016, respectively)	(2,773)			(2,773)
Acquisition of redeemable noncontrolling interest shares	283		283
Redeemable noncontrolling interests fair value and other adjustments	113		113
Acquisition of nonredeemable noncontrolling interests	2,112						2,112
Distributions to nonredeemable noncontrolling interests	(152)						(152)
Balance at Dec. 31, 2017	$ 49,833	$ 10	1,703	48,730	(13)	(2,654)	2,057
Balance (in shares) at Dec. 31, 2017	969	969
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 0			(24)	24
Net earnings attributable to UnitedHealth Group common shareholders	11,986			11,986
Net earnings attributable to nonredeemable noncontrolling interest							273
Net earnings, Including Portion Attributable to Nonredeemable Noncontrolling Interest	12,259
Other comprehensive (loss) income	(1,517)				(275)	(1,242)
Issuances of common stock, and related tax effects (in shares)		10
Issuances of common stock, and related tax effects	814	$ 0	814
Share-based compensation	$ 620		620
Common share repurchases (in shares)	(19)	(19)
Common share repurchases	$ (4,500)	$ 0	(2,974)	(1,526)
Cash dividends paid on common shares ($3.45 per share, $2.875 per share and $2.375 per share for years ended December 31, 2018, December 31, 2017 and December 31, 2016, respectively)	(3,320)			(3,320)
Redeemable noncontrolling interests fair value and other adjustments	(163)		(163)
Acquisition of nonredeemable noncontrolling interests	521						521
Distributions to nonredeemable noncontrolling interests	(228)						(228)
Balance at Dec. 31, 2018	$ 54,319	$ 10	$ 0	$ 55,846	$ (264)	$ (3,896)	$ 2,623
Balance (in shares) at Dec. 31, 2018	960	960