DERIVATIVE INSTRUMENTS (Narrative) (Details)	1 Months Ended	12 Months Ended
	Aug. 31, 2011 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2007 USD ($) agreement	Jun. 30, 2011 USD ($) agreement
Derivative [Line Items]
Number of forward starting interest rate swap agreements | agreement					15	2
Cash payments for interest rate swap agreements					$ 89,777,000
Amortized deferred gain		$ 0	$ 0	$ 3,036,000
Designated as Hedging Instrument [Member] | Cash Flow Hedges [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Notional amount of interest rate swap agreements					$ 1,500,000,000
Estimated amount of pretax loss in AOCI reclassified to earnings for the next 12-month period		399,000
Loss reclassified from AOCI		3,070,000	$ 2,008,000	9,759,000
Designated as Hedging Instrument [Member] | Cash Flow Hedges [Member] | Interest Rate Swap [Member] | Debt [Member]
Derivative [Line Items]
Loss reclassified from AOCI		$ 1,405,000		$ 7,208,000
Designated as Hedging Instrument [Member] | Fair Value Hedges [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Cash proceeds from interest rate swap agreements	$ 25,382,000
Fixed-Rate Notes [Member]
Derivative [Line Items]
Fixed-rate notes issued						$ 650,000,000
Fixed-Rate Notes [Member] | 10.125% notes due 2015 [Member]
Derivative [Line Items]
Interest rate						10.125%