Income Taxes - Difference Between Effective Income Tax Rates and Federal Statutory Rate (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Federal tax at statutory rate	34.00%	34.00%	34.00%
Federal R&D credit	3.35%	0.08%	6.11%
Valuation allowance	(29.63%)	(31.98%)	(37.09%)
State income taxes	0.04%	0.67%	2.90%
Foreign NOL rate change	2.47%	1.40%
Foreign tax rate differential	(1.60%)	(1.94%)	(1.49%)
Other	(8.79%)	(2.91%)	(5.00%)
Effective tax rate	(0.16%)	(0.68%)	(0.57%)
Federal tax at statutory rate	$ (3,891)	$ (2,483)	$ (1,844)
Federal R&D credit	(383)	(6)	(332)
Valuation allowance	3,391	2,336	2,012
State income taxes	(5)	(49)	(157)
Foreign NOL rate change	(283)	(102)
Foreign tax rate differential	183	142	81
Other	1,006	212	271
Total income tax expense	$ 18	$ 50	$ 31