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 Gains (Losses) on Investments [Member]	Foreign Currency Translation Losses [Member]	Nonredeemable Noncontrolling Interests [Member]
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
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
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
Balance at Dec. 31, 2020	$ 68,328	$ 10	0	69,295	1,336	(5,150)	2,837
Balance (in shares) at Dec. 31, 2020	946	946
Net earnings attributable to UnitedHealth Group common shareholders	$ 13,214			13,214
Net earnings attributable to nonredeemable noncontrolling interest							254
Net Earnings, Including Portion Attributable to Nonredeemable Noncontrolling Interest	13,468
Other comprehensive income (loss)	(1,042)				(558)	(484)
Issuances of common stock, and related tax effects (in shares)		6
Issuances of common stock, and related tax effects	839	$ 0	839
Share-based compensation	559		559
Common share repurchases (in shares)		(10)
Common share repurchases	(3,950)	$ 0	(586)	(3,364)
Cash dividends paid on common shares	(3,915)			(3,915)
Redeemable noncontrolling interests fair value and other adjustments	(918)		(812)	(106)
Acquisition and other adjustments of nonredeemable noncontrolling interests	125						125
Distribution to nonredeemable noncontrolling interests	(235)						(235)
Balance at Sep. 30, 2021	$ 73,259	$ 10	0	75,124	778	(5,634)	2,981
Balance (in shares) at Sep. 30, 2021	942	942
Balance at Jun. 30, 2021	$ 72,022	$ 10	0	73,090	927	(5,013)	3,008
Balance (in shares) at Jun. 30, 2021		943
Net earnings attributable to UnitedHealth Group common shareholders	4,086			4,086
Net earnings attributable to nonredeemable noncontrolling interest							86
Net Earnings, Including Portion Attributable to Nonredeemable Noncontrolling Interest	4,172
Other comprehensive income (loss)	(770)				(149)	(621)
Issuances of common stock, and related tax effects (in shares)		1
Issuances of common stock, and related tax effects	291	$ 0	291
Share-based compensation	159		159
Common share repurchases (in shares)		(2)
Common share repurchases	(1,050)	$ 0	(365)	(685)
Cash dividends paid on common shares	(1,367)			(1,367)
Redeemable noncontrolling interests fair value and other adjustments	(85)		(85)
Acquisition and other adjustments of nonredeemable noncontrolling interests	(26)						(26)
Distribution to nonredeemable noncontrolling interests	(87)						(87)
Balance at Sep. 30, 2021	$ 73,259	$ 10	$ 0	$ 75,124	$ 778	$ (5,634)	$ 2,981
Balance (in shares) at Sep. 30, 2021	942	942