Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Loss Carryforwards [Line Items]
Valuation allowances related to U.S. based deferred taxes		$ 11,300,000	$ 15,600,000
Valuation allowance	90,774,000	90,774,000	79,458,000
Statutory federal income tax rate		34.00%	34.00%	34.00%
Internal revenue code related to annual use of operating loss carry forwards		annual use of the Company’s net operating loss and research and development credit carryforwards may be limited in the event a cumulative change in ownership of more than 50% occurs within a three-year period
Internal revenue code, cumulative change in ownership (percent)		50.00%
Uncertain income tax position unrecognized		less than a 50% likelihood
Settlements and lapses in statutes of limitations		61,000	71,000
Associated interest due to expiration of the applicable statutes of limitations for certain tax years		0	236,000
Total liability for unrecognized tax benefits included other long-term liabilities		0	61,000
Interest and penalties related to unrecognized tax benefits in the provision for income taxes		0
Uncertain tax liability	61,000
Domestic Country
Operating Loss Carryforwards [Line Items]
Valuation allowance	86,000,000	86,000,000	74,700,000
Net operating loss carryforwards	174,300,000	174,300,000
Net operating loss expiration dates		2029 through 2034
Research and development tax credit carryforwards	4,300,000	4,300,000
Tax credits expiration dates		2027 through 2034
Foreign Country
Operating Loss Carryforwards [Line Items]
Valuation allowance	4,800,000	4,800,000	4,700,000
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	67,100,000	67,100,000
Net operating loss expiration dates		2017 through 2034
Research and development tax credit carryforwards	$ 5,400,000	$ 5,400,000