Commitments and Contingencies (Additional Information) (Details) - USD ($) $ in Thousands		12 Months Ended
	Oct. 14, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Rent expense		$ 9,600	$ 7,100	$ 6,600
Deferred rent credit, noncurrent		9,500	$ 400
Operating Leased Assets [Line Items]
Total lease commitments		$ 48,896
Standby letters of credit for headquarters
Operating Leased Assets [Line Items]
Maximum borrowing capacity	$ 1,200
Lease agreement for headquarters
Operating Leased Assets [Line Items]
Lease term	10 years
Total lease commitments	$ 38,600