FAIR VALUE (Assets and Liabilites Measured on a Nonrecurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Assets:
Cash and restricted cash	$ 764,943	$ 964,300	$ 753,958	$ 915,139
Liabilities:
Variable-rate debt:	1,392,732	1,350,914
Allowance for doubtful accounts	7,200	9,300
Allowance for notes receivable	100	100
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Carrying Amount
Assets:
Cash and restricted cash	714,671	914,165
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Estimated Fair Value
Assets:
Cash and restricted cash	714,671	914,165
Recurring | Significant Other Observable Inputs (Level 2) | Carrying Amount
Liabilities:
Fixed-rate debt:	1,522,490	1,526,875
Variable-rate debt:	1,392,732	1,350,914
Recurring | Significant Other Observable Inputs (Level 2) | Estimated Fair Value
Liabilities:
Fixed-rate debt:	1,507,840	1,554,766
Variable-rate debt:	1,392,732	1,350,914
Recurring | Significant Unobservable Inputs (Level 3) | Carrying Amount
Assets:
Accounts receivable, net	14,384	13,041
Notes receivable, net	8,310	5,864
Recurring | Significant Unobservable Inputs (Level 3) | Estimated Fair Value
Assets:
Accounts receivable, net	14,384	13,041
Notes receivable, net	$ 8,310	$ 5,864