Future Annual Minimum Payments Due (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Loss Contingencies [Line Items]
Minimum Lease Payments, 2013	$ 212
Minimum Lease Payments, 2014	179
Minimum Lease Payments, 2015	147
Minimum Lease Payments, 2016	110
Minimum Lease Payments, 2017	82
Minimum Lease Payments, Thereafter	122
Minimum Lease Payments, Total	852
Sublease Rental Receipts, 2013	(1)
Sublease Rental Receipts, 2014	(1)
Sublease Rental Receipts, 2015	0
Sublease Rental Receipts, 2016	0
Sublease Rental Receipts, 2017	0
Sublease Rental Receipts, Thereafter	0
Sublease Rental Receipts, Total	(2)
Net Lease Commitments, 2013	211
Net Lease Commitments, 2014	178
Net Lease Commitments, 2015	147
Net Lease Commitments, 2016	110
Net Lease Commitments, 2017	82
Net Lease Commitments, Thereafter	122
Net Lease Commitments, Total	$ 850

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

No definition available.

Name:	hum_NetOperatingLeaseCommitmentThereafter
Namespace Prefix:	hum_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	hum_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	hum_NetOperatingLeaseCommitmentWithinYearFive
Namespace Prefix:	hum_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	hum_NetOperatingLeaseCommitmentWithinYearFour
Namespace Prefix:	hum_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	hum_NetOperatingLeaseCommitmentWithinYearOne
Namespace Prefix:	hum_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	hum_NetOperatingLeaseCommitmentWithinYearThree
Namespace Prefix:	hum_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	hum_NetOperatingLeaseCommitmentWithinYearTwo
Namespace Prefix:	hum_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 98

-Paragraph 18

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

+ Details

Name:	us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsWithinOneYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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 Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 16

-Subparagraph b(i)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 122

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: 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 4: 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

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of required minimum rental payments maturing in the next fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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Period Type:	instant

- Definition

Amount of required minimum rental payments maturing in the fifth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Definition

Amount of required minimum rental payments maturing in the forth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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Period Type:	instant

- Definition

Amount of required minimum rental payments maturing in the third fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Definition

Amount of required minimum rental payments maturing in the second fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of required minimum rental payments maturing after the fifth fiscal year following the latest fiscal year for operating leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant