Fair Value Measurements - Schedule of Valuation Assumptions used in Determining Fair Value (Details) - Convertible Debt - 5.00% / 7.00% Second Lien Notes due August 31, 2022 - Level 3	Sep. 30, 2018
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs (as a percent)	0.0216
Credit spreads
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs (as a percent)	0.1393
PIK premium spread
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs (as a percent)	0.0200
Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement inputs (as a percent)	0.5000