FAIR VALUE (Assets and Liabilities Measured on a Nonrecurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets:
Cash and Restricted cash	$ 724,215	$ 964,300	$ 915,139	$ 510,137
Liabilities:
Allowance, accounts receivable	10,700	9,300
Allowance, notes receivable	100	100
Level 1 | Reported Value Measurement
Assets:
Cash and Restricted cash	724,215	914,165
Level 1 | Estimate of Fair Value Measurement
Assets:
Cash and Restricted cash	724,215	914,165
Level 3 | Reported Value Measurement
Assets:
Accounts receivable, net	12,589	13,041
Notes receivable, net	4,694	5,864
Level 3 | Estimate of Fair Value Measurement
Assets:
Accounts receivable, net	12,589	13,041
Notes receivable, net	4,694	5,864
Level 2 | Reported Value Measurement
Liabilities:
Fixed-rate debt	1,663,875	1,526,875
Variable-rate debt	1,551,336	1,350,914
Level 2 | Estimate of Fair Value Measurement
Liabilities:
Fixed-rate debt	1,608,635	1,554,766
Variable-rate debt	$ 1,551,336	$ 1,350,914