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
Mar. 31, 2018
Dec. 31, 2017
Fixed Rate Debt With Noncontrolling Interest Partner [Member]    
Estimate of fair value not practicable [Abstract]    
Face amount of debt $ 45,200 $ 44,000
Level 2 [Member] | 4.875% Senior Notes Due 2024 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of senior notes 561,459 592,325
Level 2 [Member] | 5.625% Senior Notes Due 2026 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of senior notes 304,389 0
Level 2 [Member] | 5.375% Senior Notes due 2022 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of senior notes 255,735 259,233
Level 2 [Member] | 2.5% Convertible Senior Notes Due 2023 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of convertible senior notes 556,226 0
Level 2 [Member] | 2.5% Convertible Senior Notes Due 2019 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of convertible senior notes $ 66,052 $ 310,635