Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Operating Loss Carryforwards	$ 84.7
Operating Loss Carryforwards, Expiration Dates	2032
Equity Method Investment, Ownership Percentage	50.00%
State and Local Jurisdiction [Member]
Operating Loss Carryforwards	8.1
Tax Credit Carryforward, Amount	0.9
Operating Loss Carryforwards, Expiration Dates	2032
Additional Paid-In Capital [Member]
Operating Loss Carryforwards	84.7
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost	2.5
Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	$ 1.5