Quarterly report pursuant to Section 13 or 15(d)

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

v3.5.0.2
FAIR VALUE DISCLOSURES - Schedule of Fair Value of Fixed-Rate Debt (Details) - Senior Notes [Member] - USD ($)
Sep. 30, 2016
Dec. 31, 2015
4.50% senior notes due 2018 [Member]    
Fair value of fixed-rate debt    
Debt instrument, stated rate (percent) 4.50% 4.50%
4.50% senior notes due 2018 [Member] | Level 2 [Member]    
Debt Instrument [Line Items]    
Aggregate Principal $ 175,000,000 $ 175,000,000
Fair value of fixed-rate debt    
Estimated Fair Value $ 178,938,000 $ 175,000,000
7.15% senior notes due 2020 [Member]    
Fair value of fixed-rate debt    
Debt instrument, stated rate (percent) 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 $ 333,750,000 $ 315,750,000
7.00% senior notes due 2022 [Member]    
Fair value of fixed-rate debt    
Debt instrument, stated rate (percent) 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 $ 334,500,000 $ 313,500,000
6.00% senior notes due 2025 [Member]    
Fair value of fixed-rate debt    
Debt instrument, stated rate (percent) 6.00% 6.00%
6.00% senior notes due 2025 [Member] | Level 2 [Member]    
Debt Instrument [Line Items]    
Aggregate Principal $ 200,000,000 $ 200,000,000
Fair value of fixed-rate debt    
Estimated Fair Value $ 212,500,000 $ 197,500,000
1.875% convertible senior notes due 2032 [Member]    
Fair value of fixed-rate debt    
Debt instrument, stated rate (percent) 1.875% 1.875%
1.875% convertible senior notes due 2032 [Member] | Level 2 [Member]    
Debt Instrument [Line Items]    
Aggregate Principal $ 126,500,000 $ 126,500,000
Fair value of fixed-rate debt    
Estimated Fair Value $ 126,184,000 $ 124,128,000