STOCK-BASED COMPENSATION (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended				9 Months Ended		3 Months Ended						9 Months Ended	12 Months Ended	3 Months Ended				0 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 RSUs	Mar. 31, 2013 RSUs	Sep. 30, 2012 RSUs	Mar. 31, 2012 RSUs	Sep. 30, 2013 RSUs	Sep. 30, 2012 RSUs	Mar. 31, 2013 RSUs Minimum	Mar. 31, 2012 RSUs Minimum	Mar. 31, 2013 RSUs Maximum	Mar. 31, 2012 RSUs Maximum	Mar. 31, 2013 RSUs Performance-based	Mar. 31, 2012 RSUs Performance-based	Sep. 30, 2013 RSUs Performance-based item	Dec. 31, 2012 RSUs Performance-based	Mar. 31, 2013 RSUs Performance-based Minimum	Mar. 31, 2012 RSUs Performance-based Minimum	Mar. 31, 2013 RSUs Performance-based Maximum	Mar. 31, 2012 RSUs Performance-based Maximum	May 21, 2013 2013 Stock and Incentive Compensation Plan	Sep. 30, 2013 2013 Stock and Incentive Compensation Plan
STOCK-BASED COMPENSATION
Number of shares of common stock reserved for issuance																							4,100,000
Reduction from common stock reserved for issuance for every share granted under prior plan																							1
Remaining shares available for future issuance																								3,300,000
Awards granted (in shares)						657,000		586,000	707,000						58,000	73,000
Award vesting period											3 years	3 years	4 years	4 years
Number of shares granted expected to cliff vest						300,000		130,000
Percentage of target shares which can be earned by the participants (as a percent)																			0.00%	0.00%	200.00%	200.00%
Per unit grant date fair value (in dollars per unit)									$ 20.75								$ 29.61	$ 17.34
Number of peer groups for estimating total shareholder return ranking																	2
Non-cash compensation expense	$ 2,609,000	$ 2,564,000	$ 7,753,000	$ 8,733,000	$ 2,600,000		$ 2,600,000		$ 7,800,000	$ 8,700,000
Unrecognized compensation expense
Unrecognized compensation cost, net of estimated forfeitures					$ 17,300,000				$ 17,300,000
Weighted average period for recognition of unrecognized compensation expense									1 year 10 months 24 days