Condensed 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 (Losses) Gains on Investments [Member]	Foreign Currency Translation [Member]	Nonredeemable Noncontrolling Interests [Member]
Balance at Dec. 31, 2018	$ 54,319	$ 10	$ 0	$ 55,846	$ (264)	$ (3,896)	$ 2,623
Balance (Adjustment to adopt ASU 2016-02) at Dec. 31, 2018	(18)			(13)			(5)
Balance (in shares) at Dec. 31, 2018		960
Net earnings attributable to UnitedHealth Group common shareholders	10,298			10,298
Net earnings attributable to nonredeemable noncontrolling interest							196
Net Earnings, Including Portion Attributable to Nonredeemable Noncontrolling Interest	10,494
Other comprehensive income (loss)	451				904	(453)
Issuances of common stock, and related tax effects (in shares)		8
Issuances of common stock, and related tax effects	438	$ 0	438
Share-based compensation	521		521
Common share repurchases (in shares)		(21)
Common share repurchases	(5,101)	$ (1)	(573)	(4,527)
Cash dividends paid on common shares	(2,908)			(2,908)
Redeemable noncontrolling interests fair value and other adjustments	(277)		(277)
Acquisition and other adjustments of nonredeemable noncontrolling interests	48		(109)				157
Distribution to nonredeemable noncontrolling interests	(211)						(211)
Balance at Sep. 30, 2019	57,756	$ 9	0	58,696	640	(4,349)	2,760
Balance (in shares) at Sep. 30, 2019		947
Balance at Jun. 30, 2019	55,854	$ 9	0	56,367	516	(3,789)	2,751
Balance (in shares) at Jun. 30, 2019		948
Net earnings attributable to UnitedHealth Group common shareholders	3,538			3,538
Net earnings attributable to nonredeemable noncontrolling interest							82
Net Earnings, Including Portion Attributable to Nonredeemable Noncontrolling Interest	3,620
Other comprehensive income (loss)	(436)				124	(560)
Issuances of common stock, and related tax effects (in shares)		2
Issuances of common stock, and related tax effects	277	$ 0	277
Share-based compensation	130		130
Common share repurchases (in shares)		(3)
Common share repurchases	(600)	$ 0	(415)	(185)
Cash dividends paid on common shares	(1,024)			(1,024)
Redeemable noncontrolling interests fair value and other adjustments	8		8
Acquisition and other adjustments of nonredeemable noncontrolling interests	(7)						(7)
Distribution to nonredeemable noncontrolling interests	(66)						(66)
Balance at Sep. 30, 2019	57,756	$ 9	0	58,696	640	(4,349)	2,760
Balance (in shares) at Sep. 30, 2019		947
Balance at Dec. 31, 2019	60,436	$ 9	7	61,178	589	(4,167)	2,820
Balance (Adjustment to Adopt ASU 2016-13) at Dec. 31, 2019	$ (28)			(28)
Balance (in shares) at Dec. 31, 2019	948	948
Net earnings attributable to UnitedHealth Group common shareholders	$ 13,191			13,191
Net earnings attributable to nonredeemable noncontrolling interest							159
Net Earnings, Including Portion Attributable to Nonredeemable Noncontrolling Interest	13,350
Other comprehensive income (loss)	(916)				667	(1,583)
Issuances of common stock, and related tax effects (in shares)		10
Issuances of common stock, and related tax effects	929	$ 1	928
Share-based compensation	509		509
Common share repurchases (in shares)		(9)
Common share repurchases	(2,541)	$ 0	(1,315)	(1,226)
Cash dividends paid on common shares	(3,400)			(3,400)
Redeemable noncontrolling interests fair value and other adjustments	(129)		(129)
Acquisition and other adjustments of nonredeemable noncontrolling interests	42						42
Distribution to nonredeemable noncontrolling interests	(148)						(148)
Balance at Sep. 30, 2020	$ 68,104	$ 10	0	69,715	1,256	(5,750)	2,873
Balance (in shares) at Sep. 30, 2020	949	949
Balance at Jun. 30, 2020	$ 66,515	$ 10	388	67,776	1,161	(5,711)	2,891
Balance (in shares) at Jun. 30, 2020		950
Net earnings attributable to UnitedHealth Group common shareholders	3,172			3,172
Net earnings attributable to nonredeemable noncontrolling interest							62
Net Earnings, Including Portion Attributable to Nonredeemable Noncontrolling Interest	3,234
Other comprehensive income (loss)	56				95	(39)
Issuances of common stock, and related tax effects (in shares)		2
Issuances of common stock, and related tax effects	321	$ 0	321
Share-based compensation	131		131
Common share repurchases (in shares)		(3)
Common share repurchases	(850)	$ 0	(805)	(45)
Cash dividends paid on common shares	(1,188)			(1,188)
Redeemable noncontrolling interests fair value and other adjustments	(35)		(35)
Acquisition and other adjustments of nonredeemable noncontrolling interests	(8)						(8)
Distribution to nonredeemable noncontrolling interests	(72)						(72)
Balance at Sep. 30, 2020	$ 68,104	$ 10	$ 0	$ 69,715	$ 1,256	$ (5,750)	$ 2,873
Balance (in shares) at Sep. 30, 2020	949	949