Assumptions Used in Calculating the Fair Value of Each SAR on the Date of Grant Using the Black-Scholes Valuation Model (Detail)	12 Months Ended
	Dec. 31, 2011 Year	Dec. 31, 2010 Year	Dec. 31, 2009 Year
For stock options issued by the Company:
Risk-free interest rates	2.20%	2.50%	1.60%
Expected lives (in years)	5.1	5.1	5.1
Dividend yield	0.80%	0.72%	0.38%
Expected volatility	46.40%	47.60%	48.60%
Forfeiture rate	7.50%	13.00%	13.00%