Acquisitions Schedule of Intangible Assets Acquired as Part of Business Combination (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Jun. 05, 2015	Apr. 14, 2015
Creative Circle [Member]
Acquired Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		$ 194,500
Creative Circle [Member] | Trademarks [Member]
Acquired Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		66,100
Creative Circle [Member] | Contractor Relations [Member]
Acquired Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		29,500
Creative Circle [Member] | Customer relations
Acquired Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		90,700
Creative Circle [Member] | Non-compete agreements
Acquired Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		7,300
Creative Circle [Member] | Contract-Based Intangible Assets [Member]
Acquired Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill		$ 900
LabResource [Member]
Acquired Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill			$ 7,528
LabResource [Member] | Trademarks [Member]
Acquired Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill			1,140
LabResource [Member] | Contractor Relations [Member]
Acquired Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill			947
LabResource [Member] | Customer relations
Acquired Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill			5,421
LabResource [Member] | Non-compete agreements
Acquired Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill			20
LabResource [Member] | Contract-Based Intangible Assets [Member]
Acquired Intangible Assets [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill			$ 0
Minimum [Member] | Contractor Relations [Member]
Acquired Intangible Assets [Line Items]
Acquired Finite Lived Intangible Assets Average Useful Life	2 years
Minimum [Member] | Customer relations
Acquired Intangible Assets [Line Items]
Acquired Finite Lived Intangible Assets Average Useful Life	2 years
Minimum [Member] | Non-compete agreements
Acquired Intangible Assets [Line Items]
Acquired Finite Lived Intangible Assets Average Useful Life	2 years
Minimum [Member] | Contract-Based Intangible Assets [Member]
Acquired Intangible Assets [Line Items]
Acquired Finite Lived Intangible Assets Average Useful Life	5 years
Minimum [Member] | Computer Software, Intangible Asset [Member]
Acquired Intangible Assets [Line Items]
Acquired Finite Lived Intangible Assets Average Useful Life	6 years
Maximum [Member] | Contractor Relations [Member]
Acquired Intangible Assets [Line Items]
Acquired Finite Lived Intangible Assets Average Useful Life	4 years
Maximum [Member] | Customer relations
Acquired Intangible Assets [Line Items]
Acquired Finite Lived Intangible Assets Average Useful Life	10 years
Maximum [Member] | Non-compete agreements
Acquired Intangible Assets [Line Items]
Acquired Finite Lived Intangible Assets Average Useful Life	6 years