Fixed Assets - Additional information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 66,235	$ 60,804
Accumulated depreciation and amortization	28,759	25,474
Depreciation and amortization	6,700
Assets Held under Capital Leases
Property, Plant and Equipment [Line Items]
Fixed assets, gross	4,700	3,800
Accumulated depreciation and amortization	$ 2,900	2,300
Depreciation and amortization		$ 6,300	$ 5,900