Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.1
FAIR VALUE MEASUREMENTS (Fair Value of Debt) (Details) - Level 2 [Member] - USD ($)
$ in Thousands
Mar. 31, 2020
Dec. 31, 2019
4.75% Senior Notes due 2027 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of senior notes $ 849,366 $ 983,735
4.875% Senior Notes Due 2024 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of senior notes 534,451 596,137
5.625% Senior Notes Due 2026 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of senior notes 271,479 320,553
2.5% Convertible Senior Notes Due 2023 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of convertible senior notes 517,473 675,664
2.0% Convertible Senior Notes Due 2025 [Member]    
Debt Fair Value [Line Items]    
Estimated fair values of convertible senior notes $ 322,036 $ 0