Schedule II - Valuation and Qualifying Accounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2010
Allowance for Doubtful Accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 200	$ 200		$ 450
Charged to Costs and Expenses	142	24	(242)
Deductions	(91)	(24)	(8)
Balance at End of Period	251	200	200	450
Allowance for Excess and Obsolete Inventory
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	999	2,320		4,431
Charged to Costs and Expenses	2,157	595	554
Deductions	(1,802)	(1,916)	(2,665)
Balance at End of Period	1,354	999	2,320	4,431
Warranty Reserve
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	955	484		427
Charged to Costs and Expenses	396	1,001	527
Deductions	676	(530)	(470)
Balance at End of Period	$ 675	$ 955	$ 484	$ 427