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Accounts Receivable (Details) (USD $) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013
Accounts Receivable Additional Disclosures [Abstract] |  |
Trade receivables, allowance for doubtful accounts | $ 1,200,000 us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent | $ 900,000 us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent
Accounts receivable, due date prior to applicable payroll date | 1 day |
Unbilled accounts receivable [Abstract] |  |
Accrued worksite employee payroll cost | 192,396,000 nsp_UnbilledAccruedWorksiteEmployeePayrollCosts | 173,801,000 nsp_UnbilledAccruedWorksiteEmployeePayrollCosts
Unbilled revenues | 55,645,000 us-gaap_UnbilledContractsReceivable | 50,286,000 us-gaap_UnbilledContractsReceivable
Customer prepayments | (87,887,000)us-gaap_CustomerAdvancesCurrent | (24,459,000)us-gaap_CustomerAdvancesCurrent
Unbilled accounts receivable | $ 160,154,000 nsp_Unbilled | $ 199,628,000 nsp_Unbilled

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- Definition Number of days prior to the applicable payroll date the Company generally requires clients pay invoices for service fees. + References No definition available. + Details
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- Definition Unbilled amounts due for services rendered, net of customer prepayments of unbilled amounts. + References No definition available. + Details
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- Definition Total of the carrying values as of the balance sheet date of obligations incurred through that date and payable for obligations related to services received from employees, including accrued salaries and bonuses. + References No definition available. + Details
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- Details
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- Details
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- Definition A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 4 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5074-111524 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.4) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The current portion of prepayments received from customers for goods or services to be provided in the future. + 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 210.5-02.20) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Unbilled amounts due for services rendered or to be rendered, actions taken or to be taken, or a promise to refrain from taking certain actions in accordance with the terms of a legally binding agreement between the entity and, at a minimum, one other party. An example would be amounts associated with contracts or programs where the recognized revenue for performance thereunder exceeds the amounts billed under the terms thereof as of the date of the balance sheet. + 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 210.5-02.3(c)(3)) -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 3 -Subparagraph c(3) -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 912 -SubTopic 310 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6471842&loc=d3e55302-109406 + Details
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