Segment Financial Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement [Line Items]
Premiums, revenues - unaffiliated customers	$ 49,394	$ 47,164	$ 100,034	$ 94,677
Products	8,247	8,353	16,678	16,425
Services	4,156	4,496	9,141	8,814
Investment and other income	341	582	706	987
Total revenues	62,138	60,595	126,559	120,903
Earnings from operations	9,241	4,744	14,237	9,576
Interest expense	(430)	(418)	(867)	(818)
Earnings before income taxes	8,811	4,326	13,370	8,758
Optum
Statement [Line Items]
Investment and other income	168	206	336	357
Total revenues	32,695	28,029	65,534	54,389
Earnings from operations	2,234	2,102	4,342	3,980
Interest expense	0	0	0	0
Earnings before income taxes	2,234	2,102	4,342	3,980
Unaffiliated Customers
Statement [Line Items]
Premiums, revenues - unaffiliated customers	49,394	47,164	100,034	94,677
Products	8,247	8,353	16,678	16,425
Services	4,156	4,496	9,141	8,814
Total revenues	61,797	60,013	125,853	119,916
Unaffiliated Customers | Optum
Statement [Line Items]
Premiums, revenues - unaffiliated customers	2,355	1,134	4,402	2,146
Products	8,247	8,353	16,678	16,425
Services	2,261	2,308	4,968	4,485
Total revenues	12,863	11,795	26,048	23,056
Affiliated Customers
Statement [Line Items]
Total revenues	0	0	0	0
Affiliated Customers | Optum
Statement [Line Items]
Total revenues	19,664	16,028	39,150	30,976
Operating Segments | UnitedHealthcare
Statement [Line Items]
Investment and other income	173	376	370	630
Total revenues	49,107	48,594	100,175	97,490
Earnings from operations	7,007	2,642	9,895	5,596
Interest expense	0	0	0	0
Earnings before income taxes	7,007	2,642	9,895	5,596
Operating Segments | OptumHealth
Statement [Line Items]
Investment and other income	129	186	265	318
Total revenues	9,139	7,148	18,331	13,861
Earnings from operations	841	688	1,553	1,314
Interest expense	0	0	0	0
Earnings before income taxes	841	688	1,553	1,314
Operating Segments | OptumInsight
Statement [Line Items]
Investment and other income	18	6	30	11
Total revenues	2,632	2,339	5,126	4,528
Earnings from operations	561	525	1,097	957
Interest expense	0	0	0	0
Earnings before income taxes	561	525	1,097	957
Operating Segments | OptumRx
Statement [Line Items]
Investment and other income	21	14	41	28
Total revenues	21,371	18,923	42,928	36,740
Earnings from operations	832	889	1,692	1,709
Interest expense	0	0	0	0
Earnings before income taxes	832	889	1,692	1,709
Operating Segments | Unaffiliated Customers | UnitedHealthcare
Statement [Line Items]
Premiums, revenues - unaffiliated customers	47,039	46,030	95,632	92,531
Products	0	0	0	0
Services	1,895	2,188	4,173	4,329
Total revenues	48,934	48,218	99,805	96,860
Operating Segments | Unaffiliated Customers | OptumHealth
Statement [Line Items]
Premiums, revenues - unaffiliated customers	2,355	1,134	4,402	2,146
Products	7	9	16	17
Services	1,225	1,370	2,773	2,644
Total revenues	3,587	2,513	7,191	4,807
Operating Segments | Unaffiliated Customers | OptumInsight
Statement [Line Items]
Premiums, revenues - unaffiliated customers	0	0	0	0
Products	27	22	56	45
Services	764	790	1,655	1,544
Total revenues	791	812	1,711	1,589
Operating Segments | Unaffiliated Customers | OptumRx
Statement [Line Items]
Premiums, revenues - unaffiliated customers	0	0	0	0
Products	8,213	8,322	16,606	16,363
Services	272	148	540	297
Total revenues	8,485	8,470	17,146	16,660
Operating Segments | Affiliated Customers | UnitedHealthcare
Statement [Line Items]
Total revenues	0	0	0	0
Operating Segments | Affiliated Customers | OptumHealth
Statement [Line Items]
Total revenues	5,423	4,449	10,875	8,736
Operating Segments | Affiliated Customers | OptumInsight
Statement [Line Items]
Total revenues	1,823	1,521	3,385	2,928
Operating Segments | Affiliated Customers | OptumRx
Statement [Line Items]
Total revenues	12,865	10,439	25,741	20,052
Optum Eliminations
Statement [Line Items]
Investment and other income	0	0	0	0
Total revenues	(447)	(381)	(851)	(740)
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	0	0	0	0
Services	0	0	0	0
Total revenues	0	0	0	0
Optum Eliminations | Affiliated Customers
Statement [Line Items]
Total revenues	(447)	(381)	(851)	(740)
Corporate and Eliminations
Statement [Line Items]
Investment and other income	0	0	0	0
Total revenues	(19,664)	(16,028)	(39,150)	(30,976)
Earnings from operations	0	0	0	0
Interest expense	(430)	(418)	(867)	(818)
Earnings before income taxes	(430)	(418)	(867)	(818)
Corporate and Eliminations | Unaffiliated Customers
Statement [Line Items]
Premiums, revenues - unaffiliated customers	0	0	0	0
Products	0	0	0	0
Services	0	0	0	0
Total revenues	0	0	0	0
Corporate and Eliminations | Affiliated Customers
Statement [Line Items]
Total revenues	$ (19,664)	$ (16,028)	$ (39,150)	$ (30,976)