Assumptions Used to Estimate Share-Based Compensation Expense Using Black-Scholes Model (Detail)	6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011
Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items]
Expected dividend yield
Forfeiture rate	7.00%		7.10%
Minimum
Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items]
Risk free interest rate	0.88%		2.22%
Expected volatility	71.86%		118.00%
Expected term (in years)	6 years 7 days	[1]	5 years 3 months 22 days	[1]
Maximum
Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items]
Risk free interest rate			2.89%
Expected volatility			120.00%
Expected term (in years)			6 years 3 months	[1]

[1] Expected term is calculated using SAB 107, Simplified Formula. Management has concluded that the use of the simplified method for calculating the expected term of its common stock option grants is appropriate.