Business Combinations, Goodwill and Intangible Assets - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended
	Oct. 22, 2016	Mar. 31, 2017	Mar. 31, 2016
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization expense		$ 3,498	$ 2,715
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Remaining amortization period (in years)		5 years 8 months 12 days
Leasehold benefits
Acquired Finite-Lived Intangible Assets [Line Items]
Remaining amortization period (in years)		2 years 2 months 12 days
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Remaining amortization period (in years)		4 years 8 months 12 days
Non-compete agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Remaining amortization period (in years)		2 years 3 months 18 days
Trade names and trademarks
Acquired Finite-Lived Intangible Assets [Line Items]
Remaining amortization period (in years)		5 years 3 months 18 days
Datasource Consulting, LLC
Acquired Finite-Lived Intangible Assets [Line Items]
Consideration transferred	$ 20,318
Datasource Consulting, LLC | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (in years)		6 years
Datasource Consulting, LLC | Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (in years)		5 years
Datasource Consulting, LLC | Trade names and trademarks
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life (in years)		3 years
Restricted Stock | Datasource Consulting, LLC
Acquired Finite-Lived Intangible Assets [Line Items]
Restricted common stock issued (in shares)	93,604
Restricted common stock issued, fair value	$ 4,483
Vesting period (in years)	4 years