STOCK-BASED COMPENSATION Stock Option Activity (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013
Number of Shares
Options outstanding at beginning of period (in shares)	3,186,414
Granted (in shares)	332,100
Exercised (in shares)	(95,820)
Cancelled (in shares)	(110,799)
Options outstanding at end of period (in shares)	3,311,895
Option Exercise Price
Granted, lower limit (in dollars per share)	$ 11.27
Granted, upper limit (in dollars per share)	$ 14.03
Exercised, lower limit (in dollars per share)	$ 5
Exercised, upper limit (in dollars per share)	$ 14.57
Cancelled, lower limit (in dollars per share)	$ 5
Cancelled, upper limit (in dollars per share)	$ 14.57
Weighted Average Exercise Price
Granted (in dollars per share)	$ 11.57
Exercised (in dollars per share)	$ 7.36
Cancelled (in dollars per share)	$ 11.80