LONG-TERM DEBT OBLIGATIONS - 3.50% Senior Convertible Notes (Details) (3.50% Senior Convertible Notes [Member], USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2013
3.50% Senior Convertible Notes [Member]
Debt Instrument [Line Items]
Aggregate principal amount of senior convertible notes repurchased	$ 91,600,000
Interest rate	3.50%	3.50%
Total cash consideration including accrued interest	92,100,000
Accrued interest	500,000
Financing costs	300,000
Convertible Debt		$ 3,900,000