INDEBTEDNESS (Details) (USD $)	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	May 20, 2014
Long-term debt
Long-term debt	$ 258,000,000	$ 173,000,000
Other Long-term Debt, Current	10,000,000	0
Long-term debt	248,000,000	173,000,000
Write-off of deferred financing fees	347,000	0	477,000
Debt instrument fees	1,900,000
Deferred financing fees, net of accumulated amortization	2,900,000	2,000,000
Amortization expense related to the deferred financing fees	700,000	600,000	600,000
Remaining borrowing capacity	11,400,000
Interest paid	7,300,000	5,400,000	5,400,000
Eurocurrency
Long-term debt
Basis spread on variable rate (as a percent)				1.00%
Credit agreement
Long-term debt
Maximum borrowing capacity				500,000,000
Balance of revolving credit facility
Long-term debt
Long-term debt	63,000,000	173,000,000
Balance of revolving credit facility | Federal funds rate
Long-term debt
Basis spread on variable rate (as a percent)				0.50%
Term Loan [Member]
Long-term debt
Long-term debt	195,000,000	0
Revolving Credit Facility [Member] | Credit agreement
Long-term debt
Maximum increase in the borrowing capacity that is available to the company, subject to certain limitations and satisfaction of certain conditions				300,000,000
Term Loan [Member] | Credit agreement
Long-term debt
Maximum borrowing capacity				200,000,000
Debt Instrument, Periodic Payment				2,500,000
Maximum increase in the borrowing capacity that is available to the company, subject to certain limitations and satisfaction of certain conditions				200,000,000