Weighted-Average Assumptions Used to Estimate Grant Date Fair Values for Stock Options Granted (Detail) (Stock Options)	3 Months Ended
	Mar. 31, 2012 Year	Mar. 31, 2011 Year
Stock Options
Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items]
Volatility	48.72%	47.43%
Expected term (in years)	5.00	5.00
Dividend yield	1.00%	0.93%
Risk-free interest rate	0.83%	2.01%