CREDIT FACILITY (Details)		1 Months Ended	12 Months Ended
	Feb. 02, 2016 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Jun. 04, 2013 USD ($)
Line of Credit Facility [Line Items]
Maximum borrowing capacity			$ 100,000,000
Interest expense incurred			0	$ 0	$ 0
Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity			50,000,000			$ 125,000,000
Credit agreement term		4 years
Current borrowing capacity		$ 100,000,000				$ 100,000,000
Outstanding balance			$ 0	$ 0
Letter of Credit Subfacility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity		20,000,000
Swingline Subfacility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity		$ 5,000,000
Subsequent Event [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 100,000,000
Debt covenant, maximum debt to total capitalization ratio	0.35
Subsequent Event [Member] | Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 50,000,000
Credit agreement term	4 years
Subsequent Event [Member] | Letter of Credit Subfacility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 20,000,000
Subsequent Event [Member] | Swingline Subfacility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 5,000,000