Segment Financial Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement [Line Items]
Premiums, revenues - unaffiliated customers	$ 47,164	$ 44,458	$ 94,677	$ 88,542
Products, revenues - unaffiliated customers	8,353	7,004	16,425	13,706
Services, revenues - unaffiliated customers	4,496	4,269	8,814	8,373
Investment and other income	582	355	987	653
Total revenues	60,595	56,086	120,903	111,274
Earnings from operations	4,744	4,204	9,576	8,257
Interest expense	(418)	(344)	(818)	(673)
Earnings before income taxes	4,326	3,860	8,758	7,584
Optum
Statement [Line Items]
Investment and other income	206	147	357	262
Total revenues	28,029	24,726	54,389	48,327
Earnings from operations	2,102	1,847	3,980	3,500
Interest expense	0	0	0	0
Earnings before income taxes	2,102	1,847	3,980	3,500
Unaffiliated Customers
Statement [Line Items]
Premiums, revenues - unaffiliated customers	47,164	44,458	94,677	88,542
Products, revenues - unaffiliated customers	8,353	7,004	16,425	13,706
Services, revenues - unaffiliated customers	4,496	4,269	8,814	8,373
Total revenues	60,013	55,731	119,916	110,621
Unaffiliated Customers | Optum
Statement [Line Items]
Premiums, revenues - unaffiliated customers	1,134	962	2,146	1,809
Products, revenues - unaffiliated customers	8,353	7,004	16,425	13,706
Services, revenues - unaffiliated customers	2,308	2,127	4,485	4,192
Total revenues	11,795	10,093	23,056	19,707
Affiliated Customers
Statement [Line Items]
Total revenues	0	0	0	0
Affiliated Customers | Optum
Statement [Line Items]
Total revenues	16,028	14,486	30,976	28,358
Operating Segments | UnitedHealthcare
Statement [Line Items]
Investment and other income	376	208	630	391
Total revenues	48,594	45,846	97,490	91,305
Earnings from operations	2,642	2,357	5,596	4,757
Interest expense	0	0	0	0
Earnings before income taxes	2,642	2,357	5,596	4,757
Operating Segments | OptumHealth
Statement [Line Items]
Investment and other income	186	124	318	230
Total revenues	7,148	5,941	13,861	11,700
Earnings from operations	688	570	1,314	1,058
Interest expense	0	0	0	0
Earnings before income taxes	688	570	1,314	1,058
Operating Segments | OptumInsight
Statement [Line Items]
Investment and other income	6	9	11	11
Total revenues	2,339	2,185	4,528	4,254
Earnings from operations	525	453	957	848
Interest expense	0	0	0	0
Earnings before income taxes	525	453	957	848
Operating Segments | OptumRx
Statement [Line Items]
Investment and other income	14	14	28	21
Total revenues	18,923	16,941	36,740	33,047
Earnings from operations	889	824	1,709	1,594
Interest expense	0	0	0	0
Earnings before income taxes	889	824	1,709	1,594
Operating Segments | Unaffiliated Customers | UnitedHealthcare
Statement [Line Items]
Premiums, revenues - unaffiliated customers	46,030	43,496	92,531	86,733
Products, revenues - unaffiliated customers	0	0	0	0
Services, revenues - unaffiliated customers	2,188	2,142	4,329	4,181
Total revenues	48,218	45,638	96,860	90,914
Operating Segments | Unaffiliated Customers | OptumHealth
Statement [Line Items]
Premiums, revenues - unaffiliated customers	1,134	962	2,146	1,809
Products, revenues - unaffiliated customers	9	12	17	24
Services, revenues - unaffiliated customers	1,370	1,203	2,644	2,391
Total revenues	2,513	2,177	4,807	4,224
Operating Segments | Unaffiliated Customers | OptumInsight
Statement [Line Items]
Premiums, revenues - unaffiliated customers	0	0	0	0
Products, revenues - unaffiliated customers	22	20	45	43
Services, revenues - unaffiliated customers	790	776	1,544	1,516
Total revenues	812	796	1,589	1,559
Operating Segments | Unaffiliated Customers | OptumRx
Statement [Line Items]
Premiums, revenues - unaffiliated customers	0	0	0	0
Products, revenues - unaffiliated customers	8,322	6,972	16,363	13,639
Services, revenues - unaffiliated customers	148	148	297	285
Total revenues	8,470	7,120	16,660	13,924
Operating Segments | Affiliated Customers | UnitedHealthcare
Statement [Line Items]
Total revenues	0	0	0	0
Operating Segments | Affiliated Customers | OptumHealth
Statement [Line Items]
Total revenues	4,449	3,640	8,736	7,246
Operating Segments | Affiliated Customers | OptumInsight
Statement [Line Items]
Total revenues	1,521	1,380	2,928	2,684
Operating Segments | Affiliated Customers | OptumRx
Statement [Line Items]
Total revenues	10,439	9,807	20,052	19,102
Optum Eliminations
Statement [Line Items]
Investment and other income	0	0	0	0
Total revenues	(381)	(341)	(740)	(674)
Earnings from operations	0	0	0	0
Interest expense	0	0	0	0
Earnings before income taxes	0	0	0	0
Optum Eliminations | Unaffiliated Customers
Statement [Line Items]
Premiums, revenues - unaffiliated customers	0	0	0	0
Products, revenues - unaffiliated customers	0	0	0	0
Services, revenues - unaffiliated customers	0	0	0	0
Total revenues	0	0	0	0
Optum Eliminations | Affiliated Customers
Statement [Line Items]
Total revenues	(381)	(341)	(740)	(674)
Corporate and Eliminations
Statement [Line Items]
Investment and other income	0	0	0	0
Total revenues	(16,028)	(14,486)	(30,976)	(28,358)
Earnings from operations	0	0	0	0
Interest expense	(418)	(344)	(818)	(673)
Earnings before income taxes	(418)	(344)	(818)	(673)
Corporate and Eliminations | Unaffiliated Customers
Statement [Line Items]
Premiums, revenues - unaffiliated customers	0	0	0	0
Products, revenues - unaffiliated customers	0	0	0	0
Services, revenues - unaffiliated customers	0	0	0	0
Total revenues	0	0	0	0
Corporate and Eliminations | Affiliated Customers
Statement [Line Items]
Total revenues	$ (16,028)	$ (14,486)	$ (30,976)	$ (28,358)