Fair Value Measurements - Estimated Fair Value and Carrying Value of Senior Notes (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Carrying Value	$ 3,631,506	$ 3,195,436
Secured Debt | 8.75% Senior Secured Notes Due 2020
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Carrying Value	1,301,098	0
Secured Debt | Fair Value Measurements Level 2 | 8.75% Senior Secured Notes Due 2020
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value	403,098	0
Senior Notes | 8.75% Senior Notes due 2020
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Carrying Value	392,666	445,402
Senior Notes | 7.5% Senior Notes due 2021
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Carrying Value	759,711	1,178,486
Senior Notes | 8.125% Senior Notes due 2022
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Carrying Value	527,737	750,000
Senior Notes | 7.5% Senior Notes due 2023
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Carrying Value	541,572	821,548
Senior Notes | Fair Value Measurements Level 2 | 8.75% Senior Notes due 2020
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value	39,740	303,750
Senior Notes | Fair Value Measurements Level 2 | 7.5% Senior Notes due 2021
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value	79,812	752,000
Senior Notes | Fair Value Measurements Level 2 | 8.125% Senior Notes due 2022
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value	57,749	472,500
Senior Notes | Fair Value Measurements Level 2 | 7.5% Senior Notes due 2023
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value	58,799	519,750
Convertible Debt | 8.125% Convertible Senior Notes due 2022
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Carrying Value	82,294	0
Convertible Debt | 7.5% Convertible Senior Notes due 2023
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Carrying Value	26,428	0
Convertible Debt | Fair Value Measurements Level 2 | 8.125% Convertible Senior Notes due 2022
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value	44,199	0
Convertible Debt | Fair Value Measurements Level 2 | 7.5% Convertible Senior Notes due 2023
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair Value	$ 15,125	$ 0