Geographic Information - Geographical Information Attributable to Net Sales (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues From External Customers And Long Lived Assets [Line Items]
Net sales	$ 24,744	$ 26,473	$ 26,848	$ 25,781	$ 22,344	$ 24,209	$ 24,039	$ 21,453	$ 103,846	$ 92,045	$ 83,196
Point of destination
Revenues From External Customers And Long Lived Assets [Line Items]
Net sales									103,846	92,045	83,196
United States | Point of destination
Revenues From External Customers And Long Lived Assets [Line Items]
Net sales									98,994	87,307	78,268
Canada | Point of destination
Revenues From External Customers And Long Lived Assets [Line Items]
Net sales									1,927	2,195	2,194
Other | Point of destination
Revenues From External Customers And Long Lived Assets [Line Items]
Net sales									$ 2,925	$ 2,543	$ 2,734