STOCK-BASED COMPENSATION (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
STOCK-BASED COMPENSATION
Total compensation expense related to stock options and restricted stock awards, before taxes	$ 4,100,000	$ 3,300,000	$ 7,800,000	$ 5,600,000
Total compensation expense related to stock options and restricted stock awards, net income	2,400,000	1,900,000	4,500,000	3,200,000
Net tax benefit recognized in equity for stock compensation plans			157,000	474,000
Incentive shares available to be issued	4,366,140		4,366,140
Stock Options
Summary of Stock-based Compensation Plans
Cash proceeds from stock option exercises			$ 2,200,000	$ 2,900,000