Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Tax [Line Items]
Deferred tax asset, valuation allowance	$ 36,031,000	$ 35,211,000
Reversal on deferred tax liability	1,000,000
Deferred tax assets and recognized tax benefit	1,400,000
Unrecognized tax benefits	5,897,000	4,197,000	4,421,000	2,116,000
Uncertain tax benefits that, if realized, would affect the effective tax rate	5,400,000
Income tax examination assessment	600,000
Uncertain tax positions		300,000
Additional tax provision	300,000
Accrued interest and penalties	400,000
Operating loss carryforwards state	46,400,000
Operating loss carryforwards federal	42,900,000
Federal research and development tax credits	1,900,000
State research and development tax credits	2,000,000
Federal and state net operating loss carryforwards, expiring year	2032
Operating loss carryforwards foreign	$ 41,100,000
Foreign net operating loss carryforward expire in year	2018
Federal research and development tax credits [Member]
Income Tax [Line Items]
Federal research and development tax credits expiration year	2031