Fair Value Measurement - Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis
Impairment of Long-Lived Assets to be Disposed of	$ 161,900
Nonrecurring | Principal Amount | 2022 Notes | Senior notes
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis
Debt	409,148	$ 409,148
Nonrecurring | Principal Amount | 2023 Notes | Senior notes
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis
Debt	150,000	150,000
Nonrecurring | Principal Amount | Revolving credit facility | Revolver | Line of credit
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis
Debt	181,000	178,000
Level 3 | Nonrecurring | Fair Value | Revolving credit facility | Revolver | Line of credit
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis
Debt	181,000	178,000
Level 1 | Nonrecurring | Fair Value | 2022 Notes | Senior notes
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis
Debt	289,206	393,150
Level 2 | Nonrecurring | Fair Value | 2023 Notes | Senior notes
Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis
Debt	$ 111,590	$ 153,375