Acquisitions (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Human Concepts [Member]
Business Acquisition [Line Items]
Current year or prior year payment based on terms of the agreement	$ 1.2
Galaxy Technologies, Inc. [Member]
Business Acquisition [Line Items]
Current year or prior year payment based on terms of the agreement	$ 1.4

The amount paid in the current fiscal year or paid in the prior fiscal year as additional payments based on the terms of the agreement.

No definition available.

Name:	nsp_AdditionalPaymentsPaidInCurrentYearOrPriorFiscalYearAsPurchasePriceConsideration
Namespace Prefix:	nsp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant