DERIVATIVE INSTRUMENTS (Narrative) (Details) (USD $)	1 Months Ended	12 Months Ended
	Aug. 31, 2011	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2007 agreement	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2015
Derivative [Line Items]
Number of forward starting interest rate swap agreements					15
Payments for (Proceeds from) settlement of interest rate swap agreements	$ 25,382,000				$ 89,777,000
Long-term notes issued						500,000,000
Interest rate						6.50%
Forward component of the settlement	23,387,000
Accrued interest income	1,995,000
Amortized deferred gain		10,674,000	4,334,000	4,052,000
Reclassification out of Accumulated Other Comprehensive Income [Member]
Derivative [Line Items]
Loss reclassified from AOCI		3,762,000
Interest Rate Swap Agreements [Member]
Derivative [Line Items]
Derviative, notional amount					1,500,000,000
Interest Rate Swap Agreement One
Derivative [Line Items]
Derviative, notional amount							500,000,000
Interest rate spread above London Interbank Offered Rate (LIBOR)							4.05%
Fixed interest rate under swap agreement							6.50%
Interest Rate Swap Agreement Two
Derivative [Line Items]
Derviative, notional amount							150,000,000
Interest rate spread above London Interbank Offered Rate (LIBOR)							8.03%
Fixed interest rate under swap agreement							10.125%
Debt [Member]
Derivative [Line Items]
Amortized deferred gain		8,032,000
Notes Issued One | Interest Rate Swap Agreement Two
Derivative [Line Items]
Interest rate							10.125%
Scenario, Forecast [Member]
Derivative [Line Items]
Estimated amount of pretax loss in AOCI related to interest rate swap that would be reclassified to earnings within the next 12 months								$ 4,207,000