Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUE DISCLOSURES - Schedule of Fair Value of Fixed-Rate Debt (Details)

v3.19.2
FAIR VALUE DISCLOSURES - Schedule of Fair Value of Fixed-Rate Debt (Details) - Senior Notes [Member] - USD ($)
Jun. 30, 2019
Dec. 31, 2018
7.15% senior notes due 2020 [Member]    
Fair value of fixed-rate debt    
Stated interest rate 7.15% 7.15%
7.15% senior notes due 2020 [Member] | Level 2 [Member]    
Debt Instrument [Line Items]    
Aggregate Principal $ 300,000,000 $ 300,000,000
Fair value of fixed-rate debt    
Estimated Fair Value $ 309,000,000 $ 307,500,000
7.00% senior notes due 2022 [Member]    
Fair value of fixed-rate debt    
Stated interest rate 7.00% 7.00%
7.00% senior notes due 2022 [Member] | Level 2 [Member]    
Debt Instrument [Line Items]    
Aggregate Principal $ 300,000,000 $ 300,000,000
Fair value of fixed-rate debt    
Estimated Fair Value $ 326,250,000 $ 309,750,000
6.00% senior notes due 2025 [Member]    
Fair value of fixed-rate debt    
Stated interest rate 6.00% 6.00%
6.00% senior notes due 2025 [Member] | Level 2 [Member]    
Debt Instrument [Line Items]    
Aggregate Principal $ 400,000,000 $ 400,000,000
Fair value of fixed-rate debt    
Estimated Fair Value $ 428,000,000 $ 379,520,000
5.125% senior notes due 2027 [Member]    
Fair value of fixed-rate debt    
Stated interest rate 5.125% 5.125%
5.125% senior notes due 2027 [Member] | Level 2 [Member]    
Debt Instrument [Line Items]    
Aggregate Principal $ 300,000,000 $ 300,000,000
Fair value of fixed-rate debt    
Estimated Fair Value $ 300,750,000 $ 255,750,000