COMMITMENTS, GUARANTEES AND CONTINGENCIES - Future Annual Minimum Payments Due (Detail) $ in Millions	Dec. 31, 2016 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Minimum Lease Payments, 2017	$ 185
Minimum Lease Payments, 2018	157
Minimum Lease Payments, 2019	126
Minimum Lease Payments, 2020	81
Minimum Lease Payments, 2021	53
Minimum Lease Payments, Thereafter	95
Minimum Lease Payments, Total	697
Sublease Rental Receipts, 2017	(19)
Sublease Rental Receipts, 2018	(18)
Sublease Rental Receipts, 2019	(14)
Sublease Rental Receipts, 2020	(11)
Sublease Rental Receipts, 2021	(8)
Sublease Rental Receipts, Thereafter	(17)
Sublease Rental Receipts, Total	(87)
Net Lease Commitments, 2017	166
Net Lease Commitments, 2018	139
Net Lease Commitments, 2019	112
Net Lease Commitments, 2020	70
Net Lease Commitments, 2021	45
Net Lease Commitments, Thereafter	78
Net Lease Commitments, Total	$ 610

This element represents the total net lease commitments after the fifth year following the balance sheet date.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the total net lease commitments existing as of the balance sheet date.

+ References

No definition available.

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- Definition

This element represents the total net lease commitments within the fifth year following the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	hum_
Data Type:	xbrli:monetaryItemType
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- Definition

This element represents the total net lease commitments within the fourth year following the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	hum_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

This element represents the total net lease commitments within the first year following the balance sheet date.

+ References

No definition available.

+ Details

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Namespace Prefix:	hum_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

This element represents the total net lease commitments within the third year following the balance sheet date.

+ References

No definition available.

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Data Type:	xbrli:monetaryItemType
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- Definition

This element represents the total net lease commitments within the second year following the balance sheet date.

+ References

No definition available.

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- Definition

Amount of minimum sublease rentals to be received by the seller-lessee for sale-leaseback transactions accounted for using the deposit method or as a financing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 40
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6456377&loc=d3e50824-112756

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- Definition

Amount of minimum sublease rentals for sale-leaseback transactions accounted for using the deposit method or as a financing to be received by the seller-lessee after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of minimum sublease rentals for sale-leaseback transactions accounted for using the deposit method or as a financing to be received by the seller-lessee in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of minimum sublease rentals for sale-leaseback transactions accounted for using the deposit method or as a financing to be received by the seller-lessee in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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- Definition

Amount of minimum sublease rentals for sale-leaseback transactions accounted for using the deposit method or as a financing to be received by the seller-lessee in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of minimum sublease rentals for sale-leaseback transactions accounted for using the deposit method or as a financing to be received by the seller-lessee in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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- Definition

Amount of minimum sublease rentals for sale-leaseback transactions accounted for using the deposit method or as a financing to be received by the seller-lessee in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 3)
-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41502-112717

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- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41502-112717

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 3)
-URI http://asc.fasb.org/extlink&oid=6584154&loc=d3e38371-112697

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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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