Acquisitions - Schedule of Business Acquisition, By Acquisition (Details) - USD ($) $ in Thousands	Apr. 01, 2017	Feb. 01, 2017	Jun. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill			$ 138,393	$ 127,772
Emantras
Business Acquisition [Line Items]
Cash purchase price	$ 3,191
Fair value of contingent consideration	220
Total purchase price	3,411
Goodwill	3,156
Fixed assets	50
Total assets	4,024
Accrued expenses	558
Billings in excess of costs and estimated earnings on uncompleted contracts	55
Total liabilities	613
Net assets acquired	3,411
McKinney Rogers
Business Acquisition [Line Items]
Cash purchase price		$ 3,193
Fair value of contingent consideration		4,505
Total purchase price		7,698
Goodwill		5,130
Total assets		8,608
Accrued expenses		44
Billings in excess of costs and estimated earnings on uncompleted contracts		866
Total liabilities		910
Net assets acquired		7,698
Customer Relationships | Emantras
Business Acquisition [Line Items]
Intangible assets, other than goodwill	$ 818
Acquired finite-lived intangible assets, weighted average useful life	4 years
Customer Relationships | McKinney Rogers
Business Acquisition [Line Items]
Intangible assets, other than goodwill		$ 653
Acquired finite-lived intangible assets, weighted average useful life		5 years
Marketing-Related Intangible Assets | McKinney Rogers
Business Acquisition [Line Items]
Intangible assets, other than goodwill		$ 121
Acquired finite-lived intangible assets, weighted average useful life		3 years
Technology-Based Intangible Assets | McKinney Rogers
Business Acquisition [Line Items]
Intangible assets, other than goodwill		$ 2,704
Acquired finite-lived intangible assets, weighted average useful life		5 years