Description of the call price as a percentage of outstanding principal.

No definition available.

Name:	hnt_DebtInstrumentCallFeaturePercentOfPrincipal
Namespace Prefix:	hnt_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument Failure to Perform Covenant

+ References

No definition available.

+ Details

Name:	hnt_DebtInstrumentFailureToPerformCovenant
Namespace Prefix:	hnt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument Grace Period For Defaulted Payment

+ References

No definition available.

+ Details

Name:	hnt_DebtInstrumentGracePeriodForDefaultedPayment
Namespace Prefix:	hnt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of percentage of principal due if payment of principal is triggered due to certain events.

+ References

No definition available.

+ Details

Name:	hnt_LongTermDebtContingentPaymentOfPrincipalPercentOfPrincipal
Namespace Prefix:	hnt_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum Borrowed Aggregate Principal Amount

+ References

No definition available.

+ Details

Name:	hnt_MinimumBorrowedAggregatePrincipalAmount
Namespace Prefix:	hnt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of Days in Month, Per Debt Terms

+ References

No definition available.

+ Details

Name:	hnt_NumberOfDaysInMonthPerDebtTerms
Namespace Prefix:	hnt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of Days in Year Per Debt Terms

+ References

No definition available.

+ Details

Name:	hnt_NumberOfDaysInYearPerDebtTerms
Namespace Prefix:	hnt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of Months in Year Per Debt Terms

+ References

No definition available.

+ Details

Name:	hnt_NumberOfMonthsInYearPerDebtTerms
Namespace Prefix:	hnt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Threshold Amount For Noncompliance With Senior Note Indenture.

+ References

No definition available.

+ Details

Name:	hnt_ThresholdAmountForNoncomplianceWithSeniorNoteIndenture
Namespace Prefix:	hnt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of outstanding long-term debt or borrowing associated with any securities or credit agreement for which there has been a default in principal, interest, sinking fund, or redemption provisions, or any breach of covenant that existed at the end of the period and subsequently has not been cured.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(c))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph c

-Article 4

+ Details

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

- Definition

The percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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

- Definition

The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16, 20

-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

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

- Definition

Interest rate stated in the contractual debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-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

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

+ Details

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

Financing Arrangements (Senior Notes) (Details) (USD $)	3 Months Ended		3 Months Ended	12 Months Ended
Financing Arrangements (Senior Notes) (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 6.375% Senior Notes [Member]	Dec. 31, 2007 6.375% Senior Notes [Member]
Debt Instrument [Line Items]
Debt instrument, aggregate principal amount				$ 400,000,000
Debt instrument, stated interest rate (as a percentage)				6.375%
Debt instrument, maturity date				Jun. 01, 2017
Contingent payment of principal (as a percentage)			101.00%
Default on senior notes			0
Call feature (as a percentage)			100.00%
Number of days in year per debt terms			360 days
Number of months in year per debt terms			12 months
Number of days in month, per debt terms			30 days
Debt instrument, benchmark for variable rate basis			Treasury rate
Treasury rate basis points (as a percentage)			0.30%
Senior note, failure to perform covenant	60 days
Senior note, grace period for defaulted payment	30 days
Threshold for noncompliance			50,000,000
Accelerated principal amount threshold			50,000,000
Senior notes amount	$ 399,146,000	$ 399,095,000