EMPLOYEE STOCK PURCHASE PLAN - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of discounted closing price for Employee Stock Purchase Plan	85.00%
Employee Stock Purchase Plan, common stock issued	114,000	119,000	213,000
Employee Stock Purchase Plan, weighted average price per share	$ 33.76	$ 25.59	$ 14.95