Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUE MEASUREMENTS (Fair Value of Debt) (Details)

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FAIR VALUE MEASUREMENTS (Fair Value of Debt) (Details) - USD ($)
$ in Thousands
Jun. 30, 2018
Dec. 31, 2017
Fixed Rate Debt With Noncontrolling Interest Partner [Member]    
Estimate of fair value not practicable [Abstract]    
Face amount of debt $ 43,000 $ 44,000
Level 2 [Member] | 4.875% Senior Notes Due 2024 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of senior notes 557,049 592,325
Level 2 [Member] | 5.625% Senior Notes Due 2026 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of senior notes 299,469 0
Level 2 [Member] | 5.375% Senior Notes due 2022 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of senior notes 255,415 259,233
Level 2 [Member] | 2.5% Convertible Senior Notes Due 2023 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of convertible senior notes 576,813 0
Level 2 [Member] | 2.5% Convertible Senior Notes Due 2019 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of convertible senior notes $ 40,860 $ 310,635