Revenue by Products and Services (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenue from External Customer [Line Items]
Net revenue	$ 28,290	$ 29,198	$ 30,835	$ 27,062	$ 33,432	$ 30,204	$ 31,294	$ 29,572	$ 115,385	$ 124,502	$ 129,036
Products
Revenue from External Customer [Line Items]
Net revenue									110,267	119,443	124,673
Services
Revenue from External Customer [Line Items]
Net revenue									$ 5,118	$ 5,059	$ 4,363