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Fair Value Measurements - Additional Information (Details) - USD ($)
$ in Millions
Mar. 31, 2019
Jan. 31, 2018
Debt Instrument [Line Items]    
Debt instrument interest rate (as a percent) 11.25%  
11.25% Senior Notes    
Debt Instrument [Line Items]    
Debt instrument interest rate (as a percent) 11.25% 11.25%
Fair value of senior notes $ 247.0