Acquisitions (Acquisitions Costs, by Acquisition) (Details) Share data in Millions, unless otherwise specified	9 Months Ended	0 Months Ended	5 Months Ended	9 Months Ended	0 Months Ended	12 Months Ended			0 Months Ended	12 Months Ended
	Sep. 30, 2012 USD ($)	May 15, 2012 Apex Systems USD ($)	Sep. 30, 2012 Apex Systems USD ($)	Sep. 30, 2012 Apex Systems USD ($)	Feb. 28, 2011 Valesta USD ($)	Dec. 31, 2011 Valesta USD ($)	Sep. 30, 2012 Valesta Maximum USD ($)	Feb. 28, 2011 Valesta Maximum EUR (€)	Jul. 31, 2011 HCP USD ($)	Dec. 31, 2011 HCP USD ($)	Jul. 31, 2011 HCP Maximum USD ($)
Business Acquisition [Line Items]
Effective Date of Acquisition		May 15, 2012			Feb. 28, 2011				Jul. 31, 2011
Name of Acquired Entity		Apex Systems, Inc.			Valesta				HealthCare Partners
Description of Acquired Entity		a privately-owned provider of information technology staffing and services headquartered in Richmond, Virginia			a privately-owned provider of specialized clinical research staffing headquartered in Belgium				a privately-owned provider of physician staffing headquartered in Atlanta, Georgia
Reason for Business Combination		The primary reason for the acquisition was to expand the Company's information technology staffing services.			The primary reasons for the acquisition were to expand the Life Sciences business operations and to leverage the Company’s infrastructure.				The primary reasons for the acquisition were to expand the Physician segment business operations geographic coverage and to leverage the Company’s infrastructure.
Cost of acquired entity, purchase price		$ 610,800,000			$ 23,700,000				$ 19,100,000
Cost of acquired entity, cash paid		385,000,000	300,000	300,000	16,800,000				15,700,000
Shares of Company's common stock issued (in shares)		14.3
Acquisition costs expensed				9,400,000		400,000				57,000
Revenues of acquiree included in statement of operations			301,200,000
Net loss of acquiree included in statement of operations			(900,000)
Potential future earn-out consideration					6,900,000				3,400,000
Maximum earn-out capped	$ 10,100,000						$ 6,400,000	€ 5,000,000			$ 3,700,000
Purchase Price Allocation, Methodology	Assets and liabilities of the acquired companies were recorded at their estimated fair values at the dates of acquisition. The excess purchase price over the fair value of net tangible assets and identifiable intangible assets acquired has been allocated to goodwill
Purchase Price Allocation, Status		The Company's allocation of the purchase price for Apex is preliminary, as the valuation of net working capital, pre-acquisition contingencies, income taxes, long-term liabilities, identifiable intangible assets and goodwill are still being finalized. Any material measurement period adjustments will be recorded retrospectively to the acquisition date.