XML 36 R4.htm IDEA: XBRL DOCUMENT
v2.4.0.8

CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (Parenthetical) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013
Income Statement [Abstract] |  |  |  |
Gross billings | $ 3,362 | $ 3,236 | $ 10,231 | $ 9,736
Worksite employee payroll costs | $ 2,802 | $ 2,696 | $ 8,469 | $ 8,037

X
- Definition The company's revenues are derived from its gross billings, which are based on the payroll cost of its worksite employees and a markup computed as a percentage of the payroll costs. + References No definition available. + Details
Name: | nsp_GrossBillings
Namespace Prefix: | nsp_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Payroll costs incurred (including share-based compensation) by the company's worksite employees that are directly related to services rendered by the worksite employees during the reporting period. + References No definition available. + Details
Name: | nsp_WorksiteEmployeePayrollCost
Namespace Prefix: | nsp_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_IncomeStatementAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration