SEGMENT INFORMATION - Segment Results (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Premiums	$ 22,703	$ 20,124
Services revenue	1,264	466
Total external revenues	23,967	20,590
Total intersegment revenues	0	0
Investment income (loss)	3	78
Total revenues	23,970	20,668
Benefits	19,625	17,296
Operating costs	2,886	2,007
Depreciation and amortization	170	142
Total operating expenses	22,681	19,445
Income from operations	1,289	1,223
Interest expense	90	68
Other (income) expense, net	(21)	115
Income before income taxes and equity in net earnings	1,220	1,040
Equity in net (losses) earnings	(4)	21
Segment earnings (loss)	1,216	1,061
Less: noncontrolling interests	0
Segment earnings (loss) attributable to Humana	1,216
Individual Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	17,052	14,815
Group Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	1,875	1,755
Medicare stand-alone PDP
Segment Reporting Information [Line Items]
Premiums	639	664
Total Medicare
Segment Reporting Information [Line Items]
Premiums	19,566	17,234
Fully-insured
Segment Reporting Information [Line Items]
Premiums	1,154	1,277
Specialty
Segment Reporting Information [Line Items]
Premiums	429	434
Medicaid and other
Segment Reporting Information [Line Items]
Premiums	1,554	1,179
Home solutions
Segment Reporting Information [Line Items]
Services revenue	726	24
Provider services
Segment Reporting Information [Line Items]
Services revenue	113	91
ASO and other
Segment Reporting Information [Line Items]
Services revenue	201	195
Pharmacy solutions
Segment Reporting Information [Line Items]
Services revenue	224	156
Services
Segment Reporting Information [Line Items]
Total intersegment revenues	0	0
Products
Segment Reporting Information [Line Items]
Total intersegment revenues	0	0
Operating segments | Retail
Segment Reporting Information [Line Items]
Premiums	21,302	18,591
Services revenue	6	5
Total external revenues	21,308	18,596
Total intersegment revenues	0	0
Investment income (loss)	43	52
Total revenues	21,351	18,648
Benefits	18,750	16,299
Operating costs	1,694	1,451
Depreciation and amortization	123	104
Total operating expenses	20,567	17,854
Income from operations	784	794
Interest expense	0	0
Other (income) expense, net	0	0
Income before income taxes and equity in net earnings	784	794
Equity in net (losses) earnings	0	0
Segment earnings (loss)	784	794
Less: noncontrolling interests	0
Segment earnings (loss) attributable to Humana	784
Operating segments | Retail | Individual Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	17,052	14,815
Operating segments | Retail | Group Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	1,875	1,755
Operating segments | Retail | Medicare stand-alone PDP
Segment Reporting Information [Line Items]
Premiums	639	664
Operating segments | Retail | Total Medicare
Segment Reporting Information [Line Items]
Premiums	19,566	17,234
Operating segments | Retail | Fully-insured
Segment Reporting Information [Line Items]
Premiums	182	178
Operating segments | Retail | Specialty
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Retail | Medicaid and other
Segment Reporting Information [Line Items]
Premiums	1,554	1,179
Operating segments | Retail | Home solutions
Segment Reporting Information [Line Items]
Services revenue	0	0
Operating segments | Retail | Provider services
Segment Reporting Information [Line Items]
Services revenue	0	0
Operating segments | Retail | ASO and other
Segment Reporting Information [Line Items]
Services revenue	6	5
Operating segments | Retail | Pharmacy solutions
Segment Reporting Information [Line Items]
Services revenue	0	0
Operating segments | Retail | Services
Segment Reporting Information [Line Items]
Total intersegment revenues	0	0
Operating segments | Retail | Products
Segment Reporting Information [Line Items]
Total intersegment revenues	0	0
Operating segments | Group and Specialty
Segment Reporting Information [Line Items]
Premiums	1,401	1,533
Services revenue	195	190
Total external revenues	1,596	1,723
Total intersegment revenues	14	10
Investment income (loss)	3	4
Total revenues	1,613	1,737
Benefits	1,046	1,145
Operating costs	413	397
Depreciation and amortization	22	21
Total operating expenses	1,481	1,563
Income from operations	132	174
Interest expense	0	0
Other (income) expense, net	0	0
Income before income taxes and equity in net earnings	132	174
Equity in net (losses) earnings	0	0
Segment earnings (loss)	132	174
Less: noncontrolling interests	0
Segment earnings (loss) attributable to Humana	132
Operating segments | Group and Specialty | Individual Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Group and Specialty | Group Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Group and Specialty | Medicare stand-alone PDP
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Group and Specialty | Total Medicare
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Group and Specialty | Fully-insured
Segment Reporting Information [Line Items]
Premiums	972	1,099
Operating segments | Group and Specialty | Specialty
Segment Reporting Information [Line Items]
Premiums	429	434
Operating segments | Group and Specialty | Medicaid and other
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Group and Specialty | Home solutions
Segment Reporting Information [Line Items]
Services revenue	0	0
Operating segments | Group and Specialty | Provider services
Segment Reporting Information [Line Items]
Services revenue	0	0
Operating segments | Group and Specialty | ASO and other
Segment Reporting Information [Line Items]
Services revenue	195	190
Operating segments | Group and Specialty | Pharmacy solutions
Segment Reporting Information [Line Items]
Services revenue	0	0
Operating segments | Group and Specialty | Services
Segment Reporting Information [Line Items]
Total intersegment revenues	14	10
Operating segments | Group and Specialty | Products
Segment Reporting Information [Line Items]
Total intersegment revenues	0	0
Operating segments | Healthcare Services
Segment Reporting Information [Line Items]
Premiums	0	0
Services revenue	1,063	271
Total external revenues	1,063	271
Total intersegment revenues	7,623	6,926
Investment income (loss)	2	1
Total revenues	8,688	7,198
Benefits	0	0
Operating costs	8,185	6,910
Depreciation and amortization	53	40
Total operating expenses	8,238	6,950
Income from operations	450	248
Interest expense	0	0
Other (income) expense, net	0	0
Income before income taxes and equity in net earnings	450	248
Equity in net (losses) earnings	(4)	21
Segment earnings (loss)	446	269
Less: noncontrolling interests	0
Segment earnings (loss) attributable to Humana	446
Operating segments | Healthcare Services | Individual Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Healthcare Services | Group Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Healthcare Services | Medicare stand-alone PDP
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Healthcare Services | Total Medicare
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Healthcare Services | Fully-insured
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Healthcare Services | Specialty
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Healthcare Services | Medicaid and other
Segment Reporting Information [Line Items]
Premiums	0	0
Operating segments | Healthcare Services | Home solutions
Segment Reporting Information [Line Items]
Services revenue	726	24
Operating segments | Healthcare Services | Provider services
Segment Reporting Information [Line Items]
Services revenue	113	91
Operating segments | Healthcare Services | ASO and other
Segment Reporting Information [Line Items]
Services revenue	0	0
Operating segments | Healthcare Services | Pharmacy solutions
Segment Reporting Information [Line Items]
Services revenue	224	156
Operating segments | Healthcare Services | Services
Segment Reporting Information [Line Items]
Total intersegment revenues	5,177	4,774
Operating segments | Healthcare Services | Products
Segment Reporting Information [Line Items]
Total intersegment revenues	2,446	2,152
Eliminations/ Corporate
Segment Reporting Information [Line Items]
Premiums	0	0
Services revenue	0	0
Total external revenues	0	0
Total intersegment revenues	(7,637)	(6,936)
Investment income (loss)	(45)	21
Total revenues	(7,682)	(6,915)
Benefits	(171)	(148)
Operating costs	(7,406)	(6,751)
Depreciation and amortization	(28)	(23)
Total operating expenses	(7,605)	(6,922)
Income from operations	(77)	7
Interest expense	90	68
Other (income) expense, net	(21)	115
Income before income taxes and equity in net earnings	(146)	(176)
Equity in net (losses) earnings	0	0
Segment earnings (loss)	(146)	(176)
Less: noncontrolling interests	0
Segment earnings (loss) attributable to Humana	(146)
Eliminations/ Corporate | Individual Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	0	0
Eliminations/ Corporate | Group Medicare Advantage
Segment Reporting Information [Line Items]
Premiums	0	0
Eliminations/ Corporate | Medicare stand-alone PDP
Segment Reporting Information [Line Items]
Premiums	0	0
Eliminations/ Corporate | Total Medicare
Segment Reporting Information [Line Items]
Premiums	0	0
Eliminations/ Corporate | Fully-insured
Segment Reporting Information [Line Items]
Premiums	0	0
Eliminations/ Corporate | Specialty
Segment Reporting Information [Line Items]
Premiums	0	0
Eliminations/ Corporate | Medicaid and other
Segment Reporting Information [Line Items]
Premiums	0	0
Eliminations/ Corporate | Home solutions
Segment Reporting Information [Line Items]
Services revenue	0	0
Eliminations/ Corporate | Provider services
Segment Reporting Information [Line Items]
Services revenue	0	0
Eliminations/ Corporate | ASO and other
Segment Reporting Information [Line Items]
Services revenue	0	0
Eliminations/ Corporate | Pharmacy solutions
Segment Reporting Information [Line Items]
Services revenue	0	0
Eliminations/ Corporate | Services
Segment Reporting Information [Line Items]
Total intersegment revenues	(5,191)	(4,784)
Eliminations/ Corporate | Products
Segment Reporting Information [Line Items]
Total intersegment revenues	$ (2,446)	$ (2,152)