Property and Equipment, Net - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2011 Lease
Property Plant And Equipment [Abstract]
Depreciation | $	$ 8,574	$ 7,442	$ 6,379
Description of capital leases	The leases expire in 2027 and the Company has one 10-year option to extend the term of the leases
Number of lease agreements | Lease				2
Description of capital leases	The Deemed Assets are being fully depreciated, on a straight line basis, over the 15-year term of the lease.