Acquisitions (Acquisitions Costs, by Acquisition) (Details) Share data in Millions, unless otherwise specified		1 Months Ended	12 Months Ended		0 Months Ended	12 Months Ended		0 Months Ended	12 Months Ended	0 Months Ended		12 Months Ended
	Dec. 31, 2013 USD ($)	Dec. 31, 2013 CyberCoders [Member] USD ($)	Dec. 31, 2013 CyberCoders [Member] USD ($)	Dec. 05, 2013 CyberCoders [Member] USD ($)	May 15, 2012 Apex Systems USD ($)	Dec. 31, 2012 Apex Systems USD ($)	Sep. 30, 2012 Apex Systems USD ($)	Jul. 31, 2011 HCP USD ($)	Dec. 31, 2011 HCP USD ($)	Feb. 28, 2011 Valesta USD ($)	Feb. 28, 2011 Valesta EUR (€)	Dec. 31, 2011 Valesta USD ($)
Business Acquisition [Line Items]
Effective Date of Acquisition		Dec. 05, 2013			May 15, 2012			Jul. 31, 2011		Feb. 28, 2011	Feb. 28, 2011
Name of Acquired Entity		CyberCoders Holdings, Inc			Apex Systems, Inc.			HealthCare Partners, Inc. ("HCP")		Warphi N.V. and its subsidiaries (collectively, "Valesta")	Warphi N.V. and its subsidiaries (collectively, "Valesta")
Description of Acquired Entity		a privately-owned provider of permanent placement services headquartered in Irvine, California.			a privately-owned provider of information technology staffing headquartered in Richmond, Virginia.			a privately-owned provider of physician staffing headquartered in Atlanta, Georgia		a privately-owned provider of specialized clinical research staffing headquartered in Belgium	a privately-owned provider of specialized clinical research staffing headquartered in Belgium
Reason for Business Combination		The primary reason for the acquisition was to expand the Company's permanent placement services.			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 Physician segment business operations geographic coverage and to leverage the Company’s infrastructure.		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 Life Sciences business operations and to leverage the Company’s infrastructure
Purchase price				$ 98,600,000	$ 610,800,000			$ 19,100,000		$ 23,700,000
Cost of acquired entity, cash paid				93,600,000	385,000,000		300,000	15,700,000		16,800,000
Shares of Company's common stock issued (in shares)					14.3
Business Combination, Acquisition Related Costs			1,500,000			9,800,000			57,000			400,000
Revenues of acquiree included in statement of operations		3,600,000
Net loss of acquiree included in statement of operations		(100,000)
Potential future earn-out consideration				5,000,000				3,400,000		6,900,000
Maximum earn-out capped	$ 16,000,000			$ 11,000,000				$ 3,700,000			€ 5,000,000