Deferred Revenue - Summary of Deferred Revenue (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	$ 21,526	$ 20,219
Total current portion of deferred revenue	7,414	6,878
Total long-term portion of deferred revenue	14,112	13,341
Warranty [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	16,525	15,889
Total current portion of deferred revenue	5,300
EVIDENCE.com [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	4,471	4,026
Total current portion of deferred revenue	2,100
Other [Member]
Deferred Revenue Arrangement [Line Items]
Total deferred revenue	$ 530	$ 304