Revenues by Geographic Territory (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Revenues	$ 31,851	$ 34,044	$ 32,605	$ 33,493	$ 28,497	$ 30,637	$ 30,689	$ 29,239	$ 131,993	$ 119,062	$ 117,704
United States
Segment Reporting Information [Line Items]
Revenues									75,997	69,388	68,156
Canada
Segment Reporting Information [Line Items]
Revenues									15,114	13,352	17,524
Other Countries less than 10% of revenues
Segment Reporting Information [Line Items]
Revenues									$ 40,882	$ 36,322	$ 32,024