Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other Commitments [Line Items]
Rent expense		$ 2,800	$ 2,600	$ 8,300	$ 7,200
Operating Leases, Future Minimum Payments Due, Rolling Maturity [Abstract]
Total amount of rent to be paid		76,909		76,909
Operating lease obligations less than one year		1,477		1,477
Operating lease obligations one to three years		18,131		18,131
Operating lease obligations three to five years		19,409		19,409
Operating lease obligations more than five years		37,892		37,892
Cloud Infrastructure Agreements
Purchase Obligation, Fiscal Year Maturity [Abstract]
Purchase obligations		15,559		15,559
Purchase obligations due in less than one year		8,392		8,392
Purchase obligations due one to three years		7,167		7,167
Purchase obligations due three to five years		0		0
Purchase obligations due after year five		$ 0		$ 0
Cloud Infrastructure Agreements | Subsequent Event
Other Commitments [Line Items]
Purchase obligation recognition period	3 years
Purchase Obligation, Fiscal Year Maturity [Abstract]
Purchase obligations	$ 69,800