Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Other Commitments [Line Items]
Letters of credit outstanding, amount	$ 10.1		$ 10.1		$ 6.2
Capital lease obligations	14.9		14.9		23.0
Non cancellable operating leases arrangements
Other Commitments [Line Items]
Operating lease expenses	3.0	$ 2.9	9.3	$ 8.5
Deferred rent liabilities	$ 2.6		$ 2.6		$ 2.9
Maximum | Capital lease obligations
Other Commitments [Line Items]
Lease obligation interest rates	10.00%		10.00%
Letter of Credit
Other Commitments [Line Items]
Letter of credit, fee percentage					2.50%
Letter of Credit | Minimum
Other Commitments [Line Items]
Letter of credit, fee percentage			2.50%
Letter of Credit | Maximum
Other Commitments [Line Items]
Letter of credit, fee percentage			3.00%