Segment Information - Schedule of Information Concerning Company's Principal Geographic Areas (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue	$ 43,274	$ 45,110	$ 44,277	$ 44,207	$ 42,565	$ 44,240	$ 42,299	$ 41,880	$ 176,868	$ 170,984	$ 158,862
Total long-lived assets excluding deferred tax assets, net	144,534				160,658				144,534	160,658
Total assets	385,313				358,327				385,313	358,327
U.S.
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue									146,850	138,458	124,686
Total long-lived assets excluding deferred tax assets, net	141,392				156,926				141,392	156,926
Total assets	374,568				349,965				374,568	349,965
Canada
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue									21,978	23,975	25,168
Total long-lived assets excluding deferred tax assets, net	3,142				3,732				3,142	3,732
Total assets	$ 10,745				7,469				10,745	7,469
Outside U.S. and Canada
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenue									$ 8,040	8,551	$ 9,008
Total assets					$ 893					$ 893