Operating Segment and Enterprise Wide Reporting - Schedule of Net Revenues by Geographic Destination and as a Percentage of Total Revenues (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]
Revenue	$ 80,975	$ 74,753	$ 82,811	$ 75,187	$ 80,681	$ 75,363	$ 82,947	$ 73,071	$ 313,726	$ 312,062	$ 297,650
Revenues by geographical area percentage									100.00%	100.00%	100.00%
United States [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue									$ 241,025	$ 232,440	$ 218,900
Revenues by geographical area percentage									77.00%	74.00%	74.00%
Europe (Excluding United Kingdom) [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue									$ 24,607	$ 30,257	$ 30,956
Revenues by geographical area percentage									8.00%	10.00%	10.00%
United Kingdom [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue									$ 16,815	$ 16,804	$ 16,293
Revenues by geographical area percentage									5.00%	5.00%	5.00%
Canada [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue									$ 14,424	$ 17,089	$ 16,995
Revenues by geographical area percentage									5.00%	6.00%	6.00%
Other [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenue									$ 16,855	$ 15,472	$ 14,506
Revenues by geographical area percentage									5.00%	5.00%	5.00%