Quarterly report pursuant to Section 13 or 15(d)

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

v3.4.0.3
FAIR VALUE DISCLOSURES - Schedule of Fair Value of Fixed-Rate Debt (Details) - Senior Notes [Member] - Level 2 [Member] - USD ($)
Mar. 31, 2016
Dec. 31, 2015
4.50% senior notes due 2018 [Member]    
Debt Instrument [Line Items]    
Aggregate Principal $ 175,000,000 $ 175,000,000
Fair value of fixed-rate debt    
Estimated Fair Value 176,750,000 175,000,000
7.15% senior notes due 2020 [Member]    
Debt Instrument [Line Items]    
Aggregate Principal 300,000,000 300,000,000
Fair value of fixed-rate debt    
Estimated Fair Value 316,500,000 315,750,000
7.00% senior notes due 2022 [Member]    
Debt Instrument [Line Items]    
Aggregate Principal 300,000,000 300,000,000
Fair value of fixed-rate debt    
Estimated Fair Value 319,500,000 313,500,000
6.00% senior notes due 2025 [Member]    
Debt Instrument [Line Items]    
Aggregate Principal 200,000,000 200,000,000
Fair value of fixed-rate debt    
Estimated Fair Value 200,000,000 197,500,000
1.875% convertible senior notes due 2032 [Member]    
Debt Instrument [Line Items]    
Aggregate Principal 126,500,000 126,500,000
Fair value of fixed-rate debt    
Estimated Fair Value $ 124,761,000 $ 124,128,000