Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Property Plant And Equipment [Line Items]
Assets under capital leases	$ 200		$ 200		$ 1,400
Accumulated depreciation - assets under capital leases					900
Depreciation	3,195	$ 3,242	6,629	$ 6,460
Accumulated depreciation	65,939		65,939		59,929
Internally developed software
Property Plant And Equipment [Line Items]
Depreciation			2,100	$ 2,900
Accumulated depreciation	$ 31,600		$ 31,600		$ 29,400