SEGMENT INFORMATION - Segment Results (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Premiums	$ 79,822	$ 74,186	$ 62,948
Services revenue	3,055	1,815	1,439
Total external revenues	82,877	76,001	64,387
Total intersegment revenues	0	0	0
Investment income	187	1,154	501
Total revenues	83,064	77,155	64,888
Benefits	69,199	61,628	53,857
Operating costs	10,121	10,052	7,381
Depreciation and amortization	596	489	458
Total operating expenses	79,916	72,169	61,696
Income (loss) from operations	3,148	4,986	3,192
Interest expense	326	283	242
Other (income) expense, net	(532)	103	(506)
Income before income taxes and equity in net earnings	3,354	4,600	3,456
Equity in net earnings	65	74	14
Segment earnings	3,419	4,674	3,470
Less: noncontrolling interests	(1)
Segment earnings attributable to Humana	3,418
Individual Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	58,654	51,697	43,128
Group Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	6,955	7,774	6,475
Medicare stand-alone PDP
Segment Reporting Information [Line Items]
Premiums	2,371	2,742	3,165
Total Medicare
Segment Reporting Information [Line Items]
Premiums	67,980	62,213	52,768
Fully-insured
Segment Reporting Information [Line Items]
Premiums	5,002	6,051	5,711
Specialty
Segment Reporting Information [Line Items]
Premiums	1,731	1,699	1,571
Medicaid and other
Segment Reporting Information [Line Items]
Premiums	5,109	4,223	2,898
Home Solutions
Segment Reporting Information [Line Items]
Services revenue	1,166	107	140
Provider
Segment Reporting Information [Line Items]
Services revenue	413	328	306
ASO and other
Segment Reporting Information [Line Items]
Services revenue	839	799	807
Pharmacy
Segment Reporting Information [Line Items]
Services revenue	637	581	186
Services
Segment Reporting Information [Line Items]
Total intersegment revenues	0	0	0
Products
Segment Reporting Information [Line Items]
Total intersegment revenues	0	0	0
Operating Segments | Retail
Segment Reporting Information [Line Items]
Premiums	73,820	67,124	56,254
Services revenue	23	19	17
Total external revenues	73,843	67,143	56,271
Total intersegment revenues	1	0	0
Investment income	200	155	195
Total revenues	74,044	67,298	56,466
Benefits	64,907	56,537	48,602
Operating costs	6,764	7,402	5,306
Depreciation and amortization	436	342	323
Total operating expenses	72,107	64,281	54,231
Income (loss) from operations	1,937	3,017	2,235
Interest expense	0	0	0
Other (income) expense, net	0	0	0
Income before income taxes and equity in net earnings	1,937	3,017	2,235
Equity in net earnings	0	0	0
Segment earnings	1,937	3,017	2,235
Less: noncontrolling interests	0
Segment earnings attributable to Humana	1,937
Operating Segments | Retail | Individual Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	58,654	51,697	43,128
Operating Segments | Retail | Group Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	6,955	7,774	6,475
Operating Segments | Retail | Medicare stand-alone PDP
Segment Reporting Information [Line Items]
Premiums	2,371	2,742	3,165
Operating Segments | Retail | Total Medicare
Segment Reporting Information [Line Items]
Premiums	67,980	62,213	52,768
Operating Segments | Retail | Fully-insured
Segment Reporting Information [Line Items]
Premiums	731	688	588
Operating Segments | Retail | Specialty
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Retail | Medicaid and other
Segment Reporting Information [Line Items]
Premiums	5,109	4,223	2,898
Operating Segments | Retail | Home Solutions
Segment Reporting Information [Line Items]
Services revenue	0	0	0
Operating Segments | Retail | Provider
Segment Reporting Information [Line Items]
Services revenue	0	0	0
Operating Segments | Retail | ASO and other
Segment Reporting Information [Line Items]
Services revenue	23	19	17
Operating Segments | Retail | Pharmacy
Segment Reporting Information [Line Items]
Services revenue	0	0	0
Operating Segments | Retail | Services
Segment Reporting Information [Line Items]
Total intersegment revenues	1	0	0
Operating Segments | Retail | Products
Segment Reporting Information [Line Items]
Total intersegment revenues	0	0	0
Operating Segments | Group and Specialty
Segment Reporting Information [Line Items]
Premiums	6,002	6,460	6,694
Services revenue	816	780	790
Total external revenues	6,818	7,240	7,484
Total intersegment revenues	40	29	18
Investment income	14	16	23
Total revenues	6,872	7,285	7,525
Benefits	4,951	5,529	5,758
Operating costs	1,687	1,818	1,651
Depreciation and amortization	85	81	88
Total operating expenses	6,723	7,428	7,497
Income (loss) from operations	149	(143)	28
Interest expense	0	0	0
Other (income) expense, net	0	0	0
Income before income taxes and equity in net earnings	149	(143)	28
Equity in net earnings	0	0	0
Segment earnings	149	(143)	28
Less: noncontrolling interests	0
Segment earnings attributable to Humana	149
Operating Segments | Group and Specialty | Individual Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Group and Specialty | Group Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Group and Specialty | Medicare stand-alone PDP
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Group and Specialty | Total Medicare
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Group and Specialty | Fully-insured
Segment Reporting Information [Line Items]
Premiums	4,271	4,761	5,123
Operating Segments | Group and Specialty | Specialty
Segment Reporting Information [Line Items]
Premiums	1,731	1,699	1,571
Operating Segments | Group and Specialty | Medicaid and other
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Group and Specialty | Home Solutions
Segment Reporting Information [Line Items]
Services revenue	0	0	0
Operating Segments | Group and Specialty | Provider
Segment Reporting Information [Line Items]
Services revenue	0	0	0
Operating Segments | Group and Specialty | ASO and other
Segment Reporting Information [Line Items]
Services revenue	816	780	790
Operating Segments | Group and Specialty | Pharmacy
Segment Reporting Information [Line Items]
Services revenue	0	0	0
Operating Segments | Group and Specialty | Services
Segment Reporting Information [Line Items]
Total intersegment revenues	40	29	18
Operating Segments | Group and Specialty | Products
Segment Reporting Information [Line Items]
Total intersegment revenues	0	0	0
Operating Segments | Healthcare Services
Segment Reporting Information [Line Items]
Premiums	0	0	0
Services revenue	2,216	1,016	632
Total external revenues	2,216	1,016	632
Total intersegment revenues	29,022	27,419	25,149
Investment income	4	13	2
Total revenues	31,242	28,448	25,783
Benefits	0	0	0
Operating costs	29,801	27,395	24,852
Depreciation and amortization	177	183	156
Total operating expenses	29,978	27,578	25,008
Income (loss) from operations	1,264	870	775
Interest expense	0	0	0
Other (income) expense, net	0	0	0
Income before income taxes and equity in net earnings	1,264	870	775
Equity in net earnings	65	74	14
Segment earnings	1,329	944	789
Less: noncontrolling interests	(1)
Segment earnings attributable to Humana	1,328
Operating Segments | Healthcare Services | Individual Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Healthcare Services | Group Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Healthcare Services | Medicare stand-alone PDP
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Healthcare Services | Total Medicare
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Healthcare Services | Fully-insured
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Healthcare Services | Specialty
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Healthcare Services | Medicaid and other
Segment Reporting Information [Line Items]
Premiums	0	0	0
Operating Segments | Healthcare Services | Home Solutions
Segment Reporting Information [Line Items]
Services revenue	1,166	107	140
Operating Segments | Healthcare Services | Provider
Segment Reporting Information [Line Items]
Services revenue	413	328	306
Operating Segments | Healthcare Services | ASO and other
Segment Reporting Information [Line Items]
Services revenue	0	0	0
Operating Segments | Healthcare Services | Pharmacy
Segment Reporting Information [Line Items]
Services revenue	637	581	186
Operating Segments | Healthcare Services | Services
Segment Reporting Information [Line Items]
Total intersegment revenues	19,998	19,491	18,255
Operating Segments | Healthcare Services | Products
Segment Reporting Information [Line Items]
Total intersegment revenues	9,024	7,928	6,894
Eliminations/ Corporate
Segment Reporting Information [Line Items]
Premiums	0	602	0
Services revenue	0	0	0
Total external revenues	0	602	0
Total intersegment revenues	(29,063)	(27,448)	(25,167)
Investment income	(31)	970	281
Total revenues	(29,094)	(25,876)	(24,886)
Benefits	(659)	(438)	(503)
Operating costs	(28,131)	(26,563)	(24,428)
Depreciation and amortization	(102)	(117)	(109)
Total operating expenses	(28,892)	(27,118)	(25,040)
Income (loss) from operations	(202)	1,242	154
Interest expense	326	283	242
Other (income) expense, net	(532)	103	(506)
Income before income taxes and equity in net earnings	4	856	418
Equity in net earnings	0	0	0
Segment earnings	4	856	418
Less: noncontrolling interests	0
Segment earnings attributable to Humana	4
Eliminations/ Corporate | Individual Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	0	0	0
Eliminations/ Corporate | Group Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	0	0	0
Eliminations/ Corporate | Medicare stand-alone PDP
Segment Reporting Information [Line Items]
Premiums	0	0	0
Eliminations/ Corporate | Total Medicare
Segment Reporting Information [Line Items]
Premiums	0	0	0
Eliminations/ Corporate | Fully-insured
Segment Reporting Information [Line Items]
Premiums	0	602	0
Eliminations/ Corporate | Specialty
Segment Reporting Information [Line Items]
Premiums	0	0	0
Eliminations/ Corporate | Medicaid and other
Segment Reporting Information [Line Items]
Premiums	0	0	0
Eliminations/ Corporate | Home Solutions
Segment Reporting Information [Line Items]
Services revenue	0	0	0
Eliminations/ Corporate | Provider
Segment Reporting Information [Line Items]
Services revenue	0	0	0
Eliminations/ Corporate | ASO and other
Segment Reporting Information [Line Items]
Services revenue	0	0	0
Eliminations/ Corporate | Pharmacy
Segment Reporting Information [Line Items]
Services revenue	0	0	0
Eliminations/ Corporate | Services
Segment Reporting Information [Line Items]
Total intersegment revenues	(20,039)	(19,520)	(18,273)
Eliminations/ Corporate | Products
Segment Reporting Information [Line Items]
Total intersegment revenues	$ (9,024)	$ (7,928)	$ (6,894)