Key Assumptions as Part of Black-Scholes Option Pricing Model (Detail)	9 Months Ended
	Sep. 30, 2012
Employee Stock Option
Share based Compensation Arrangement Assumptions Used to Estimate Fair Values of Share Options Granted [Line Items]
Expected term (in years)	6 years
Risk-free interest rate	1.24%
Dividend yield	1.33%
Expected volatility	59.90%
SARs
Share based Compensation Arrangement Assumptions Used to Estimate Fair Values of Share Options Granted [Line Items]
Expected term (in years)	6 years
Risk-free interest rate	1.24%
Dividend yield	1.33%
Expected volatility	59.90%