FAIR VALUE (Assets and Liabilities Not Measured at Fair Value) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Assets:
Cash and restricted cash	$ 842,629	$ 724,215	$ 612,548	$ 964,300
Liabilities:
Variable-rate debt	1,653,637	1,551,336
Allowance for doubtful accounts	9,700	10,700
Allowance for notes receivable	200	100
Level 1 | Carrying Amount
Assets:
Cash and restricted cash	842,629	724,215
Level 1 | Estimated Fair Value
Assets:
Cash and restricted cash	842,629	724,215
Level 3 | Carrying Amount
Assets:
Accounts receivable, net	17,248	12,589
Notes receivable, net	36,425	4,694
Level 3 | Estimated Fair Value
Assets:
Accounts receivable, net	17,248	12,589
Notes receivable, net	36,425	4,694
Level 2 | Carrying Amount
Liabilities:
Fixed-rate debt	2,011,626	1,663,875
Variable-rate debt	1,653,637	1,551,336
Level 2 | Estimated Fair Value
Liabilities:
Fixed-rate debt	2,052,785	1,608,635
Variable-rate debt	$ 1,653,637	$ 1,551,336