INDEBTEDNESS (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Feb. 03, 2012 Eurocurrency	Dec. 31, 2013 Credit agreement	Dec. 31, 2012 Credit agreement	Feb. 03, 2012 Credit agreement	Dec. 31, 2013 Revolving credit facility	Dec. 31, 2012 Revolving credit facility	Feb. 03, 2012 Revolving credit facility Federal funds rate
Long-term debt
Long-term debt								$ 173,000,000	$ 193,000,000
Maximum borrowing capacity							450,000,000.0
Maximum increase in the borrowing capacity that is available to the company, subject to certain limitations and satisfaction of certain conditions							200,000,000.0
Basis spread on variable rate (as a percent)				1.00%						0.50%
Variable rate (as a percent)								1.92%	1.96%
Outstanding letters of credit					5,800,000	6,300,000
Write-off of deferred financing fees	0	477,000	0
Debt instrument fees		2,900,000
Deferred financing fees, net of accumulated amortization	2,000,000	2,600,000
Amortization expense related to the deferred financing fees	600,000	600,000	600,000
Remaining borrowing capacity	12,000,000
Interest paid	$ 5,400,000	$ 5,400,000	$ 9,800,000