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Business Combinations, Allocation of Total Purchase Price Consideration (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Goodwill	$ 236,130,000us-gaap_Goodwill	$ 193,510,000us-gaap_Goodwill	$ 160,936,000us-gaap_Goodwill
TriTek [Member]
Business Acquisition [Line Items]
Acquired tangible assets	11,900,000
Acquired intangible assets	6,200,000
Liabilities assumed	(6,100,000)
Goodwill	9,100,000
Total purchase price	21,100,000
ClearTask [Member]
Business Acquisition [Line Items]
Acquired tangible assets	2,100,000
Acquired intangible assets	1,600,000
Liabilities assumed	(800,000)
Goodwill	5,700,000
Total purchase price	8,600,000
CoreMatrix [Member]
Business Acquisition [Line Items]
Acquired tangible assets	3,600,000
Acquired intangible assets	4,800,000
Liabilities assumed	(1,500,000)
Goodwill	17,600,000
Total purchase price	24,500,000
ForwardThink [Member]
Business Acquisition [Line Items]
Acquired tangible assets	4,500,000
Acquired intangible assets	18,000,000
Liabilities assumed	(11,900,000)
Goodwill	29,500,000
Total purchase price	40,100,000
BioPharm [Member]
Business Acquisition [Line Items]
Acquired tangible assets	3,400,000
Acquired intangible assets	8,400,000
Liabilities assumed	(1,200,000)
Goodwill	5,700,000
Total purchase price	16,300,000
Trifecta [Member]
Business Acquisition [Line Items]
Acquired tangible assets	1,600,000
Acquired intangible assets	5,200,000
Liabilities assumed	(5,700,000)
Goodwill	7,100,000
Total purchase price	$ 8,200,000