Commitments and Contingencies - Additional Information (Details)	Mar. 31, 2017 USD ($) letter_of_credit
Debt Instrument [Line Items]
Number of letters of credit \| letter_of_credit	2
Standby Letters of Credit
Debt Instrument [Line Items]
Current borrowing capacity	$ 17,800,000
First lien credit facility \| Credit Facility
Debt Instrument [Line Items]
Line of credit facility	75,000,000.0
Unused portion of facility	59,500,000
First lien credit facility \| Letter of Credit
Debt Instrument [Line Items]
Line of credit facility	40,000,000.0
First lien credit facility \| Swingline
Debt Instrument [Line Items]
Line of credit facility	10,000,000.0
Workers' Compensation Obligation \| Line of Credit
Debt Instrument [Line Items]
Line of credit facility	5,000,000.0
Unused portion of facility	$ 2,700,000

Number of Letters of Credit

No definition available.

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Namespace Prefix:	tnet_
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Balance Type:	na
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Details

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Namespace Prefix:
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_CreditFacilityAxis=tnet_SwinglineMember
Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=tnet_WorkersCompensationObligationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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