Segment Financial Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement [Line Items]
Premiums, revenues - unaffiliated customers	$ 50,640	$ 47,513
Products	8,431	8,072
Services	4,985	4,318
Investment and other income	365	405
Total revenues	64,421	60,308
Earnings from operations	4,996	4,832
Interest expense	(437)	(400)
Earnings before income taxes	4,559	4,432
Optum
Statement [Line Items]
Investment and other income	168	151
Total revenues	32,839	26,360
Earnings from operations	2,108	1,878
Interest expense	0	0
Earnings before income taxes	2,108	1,878
Unaffiliated Customers
Statement [Line Items]
Premiums, revenues - unaffiliated customers	50,640	47,513
Products	8,431	8,072
Services	4,985	4,318
Total revenues	64,056	59,903
Unaffiliated Customers | Optum
Statement [Line Items]
Premiums, revenues - unaffiliated customers	2,047	1,012
Products	8,431	8,072
Services	2,707	2,177
Total revenues	13,185	11,261
Affiliated Customers
Statement [Line Items]
Total revenues	0	0
Affiliated Customers | Optum
Statement [Line Items]
Total revenues	19,486	14,948
Operating Segments | UnitedHealthcare
Statement [Line Items]
Investment and other income	197	254
Total revenues	51,068	48,896
Earnings from operations	2,888	2,954
Interest expense	0	0
Earnings before income taxes	2,888	2,954
Operating Segments | OptumHealth
Statement [Line Items]
Investment and other income	136	132
Total revenues	9,192	6,713
Earnings from operations	712	626
Interest expense	0	0
Earnings before income taxes	712	626
Operating Segments | OptumInsight
Statement [Line Items]
Investment and other income	12	5
Total revenues	2,494	2,189
Earnings from operations	536	432
Interest expense	0	0
Earnings before income taxes	536	432
Operating Segments | OptumRx
Statement [Line Items]
Investment and other income	20	14
Total revenues	21,557	17,817
Earnings from operations	860	820
Interest expense	0	0
Earnings before income taxes	860	820
Operating Segments | Unaffiliated Customers | UnitedHealthcare
Statement [Line Items]
Premiums, revenues - unaffiliated customers	48,593	46,501
Products	0	0
Services	2,278	2,141
Total revenues	50,871	48,642
Operating Segments | Unaffiliated Customers | OptumHealth
Statement [Line Items]
Premiums, revenues - unaffiliated customers	2,047	1,012
Products	9	8
Services	1,548	1,274
Total revenues	3,604	2,294
Operating Segments | Unaffiliated Customers | OptumInsight
Statement [Line Items]
Premiums, revenues - unaffiliated customers	0	0
Products	29	23
Services	891	754
Total revenues	920	777
Operating Segments | Unaffiliated Customers | OptumRx
Statement [Line Items]
Premiums, revenues - unaffiliated customers	0	0
Products	8,393	8,041
Services	268	149
Total revenues	8,661	8,190
Operating Segments | Affiliated Customers | UnitedHealthcare
Statement [Line Items]
Total revenues	0	0
Operating Segments | Affiliated Customers | OptumHealth
Statement [Line Items]
Total revenues	5,452	4,287
Operating Segments | Affiliated Customers | OptumInsight
Statement [Line Items]
Total revenues	1,562	1,407
Operating Segments | Affiliated Customers | OptumRx
Statement [Line Items]
Total revenues	12,876	9,613
Optum Eliminations
Statement [Line Items]
Investment and other income	0	0
Total revenues	(404)	(359)
Earnings from operations	0	0
Interest expense	0	0
Earnings before income taxes	0	0
Optum Eliminations | Unaffiliated Customers
Statement [Line Items]
Premiums, revenues - unaffiliated customers	0	0
Products	0	0
Services	0	0
Total revenues	0	0
Optum Eliminations | Affiliated Customers
Statement [Line Items]
Total revenues	(404)	(359)
Corporate and Eliminations
Statement [Line Items]
Investment and other income	0	0
Total revenues	(19,486)	(14,948)
Earnings from operations	0	0
Interest expense	(437)	(400)
Earnings before income taxes	(437)	(400)
Corporate and Eliminations | Unaffiliated Customers
Statement [Line Items]
Premiums, revenues - unaffiliated customers	0	0
Products	0	0
Services	0	0
Total revenues	0	0
Corporate and Eliminations | Affiliated Customers
Statement [Line Items]
Total revenues	$ (19,486)	$ (14,948)