ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Summary of Changes in Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at the beginning of the period				$ 3,188,551	$ 2,571,510
Other comprehensive income before reclassifications		$ 6,054	$ (2,862)	14,325	(2,702)
Loss (gain) reclassified from accumulated other comprehensive loss to net income (loss)		(652)	133	(868)	331
Adjustment related to adoption of ASU 2018-02	[1]	0	0	(1,148)	0
Adjustment related to adoption of ASU 2017-12	[2]	0	0	(739)	0
Pension adjustment	[3]	(2,010)	0	(2,010)	0
Terminated swap amortization		(80)	0	(80)	0
Net current-period other comprehensive income		3,312	(2,729)	9,480	(2,371)
Balance at the end of the period		3,150,611	2,967,493	3,150,611	2,967,493
Accumulated Other Comprehensive (Loss) Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at the beginning of the period		(797)	(6,428)	(6,965)	(6,786)
Adjustment related to adoption of ASU 2018-02				(1,148)
Adjustment related to adoption of ASU 2017-12				(739)
Pension adjustment				(2,010)
Terminated swap amortization				(80)
Balance at the end of the period		$ 2,515	$ (9,157)	$ 2,515	$ (9,157)

[1] The Company adopted Accounting Standards Update ("ASU") 2018-02, Income Statement-Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, as of January 1, 2018. See Note 2 - Accounting Policies and Pronouncements for further discussion.

[2] The Company adopted ASU 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities, as of January 1, 2018. See Note 2 - Accounting Policies and Pronouncements for further discussion.

[3] Net of deferred tax benefit of $0.6 million, for the three and six months ended June 30, 2018