FAIR VALUE OF FINANCIAL INSTRUMENTS (Assets and Liabiliites Measured on a Nonrecurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Liabilities:
Allowance, Accounts receivable	$ 8,600	$ 7,900
Recurring
Assets:
Cash	50,041	18
Recurring | Level 1
Assets:
Cash	50,041	18
Recurring | Level 1 | Carrying Amount
Assets:
Cash	551,893	665,492
Recurring | Level 1 | Estimated Fair Value
Assets:
Cash	551,893	665,492
Recurring | Level 2 | Carrying Amount
Liabilities:
Fixed-rate debt	1,508,746	1,184,141
Variable-rate debt	1,505,534	1,524,319
Recurring | Level 2 | Estimated Fair Value
Liabilities:
Fixed-rate debt	1,529,282	1,224,573
Variable-rate debt	1,505,534	1,524,319
Recurring | Level 3 | Carrying Amount
Assets:
Accounts receivable, net	9,654	10,038
Recurring | Level 3 | Estimated Fair Value
Assets:
Accounts receivable, net	$ 9,654	$ 10,038