Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2015	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes Disclosure [Line Items]
Deferred Tax Assets, Valuation Allowance	$ 3,087		$ 3,087	$ 2,331
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount			800
Unrecognized Tax Benefits	7,684	$ 7,765	7,684	7,065	$ 7,765	$ 9,051
Deferred tax benefits	1,300		1,300	1,500
Federal Net Operating Loss carryforwards	1,500		1,500
State Net Operating Loss carryforwards	17,600		17,600
Federal alternative minimum tax credit			500
Gross research credits		1,046	722	765
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Amount		527	0	0
Deferred Tax Liabilities, Undistributed Foreign Earnings	400		$ 400
Cumulative changes in ownership percentage			50.00%
Cumulative changes in ownership period			3 years
Realized upon settlement			50.00%
Unrecognized tax benefits that would impact effective tax rate	5,600		$ 5,600	5,200
Accrued interest and penalties associated with uncertain tax positions	200		200
Interest expense, net of accrued interest reversed		$ (300)	100	(200)
Income tax reserves and related interest				$ 1,000	3,500
Federal research credits [Member]
Income Taxes Disclosure [Line Items]
Federal research credits	2,700		$ 2,700
Federal research credits, expiration date			Dec. 31, 2032
Gross State Research Credits [Member]
Income Taxes Disclosure [Line Items]
Gross research credits			$ 7,900
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Amount			7,700
Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Amount			$ 200
Federal [Member]
Income Taxes Disclosure [Line Items]
Gross research credits	$ 400				$ 500