Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounting Policies [Abstract]
Impairment of investments	$ 0	$ 0
Reduced inventory and increased costs of goods sold	2,400,000	604,000	719,000
Based on these sales prices reduced inventory and increased cost of goods sold	1,700,000	421,000	1,500,000
The recycling of boules reduced inventory and increased cost of goods sold			927,000
Depreciation and amortization expense associated with property and equipment	13,637,000	12,660,000	12,027,000
Impairment losses on long lived assets	0	0	0
Deposit at a financial institution	1,500,000	4,800,000
Revenue recorded from government contract	689,000.0	1,400,000	1,200,000
Total value of the contract	4,700,000
Period of contract	3 years
Research and development costs	1,861,000	2,263,000	2,274,000
Income tax benefit recognition criteria percentage threshold	50.00%
Interest or penalties related to income taxes accrued or recognized	$ 0	$ 0
Period of exemption from Malaysian income tax	10 years