Fair Value Measurements - Narrative (Details)	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	May 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stock price increase	400.00%
8.00% Convertible Senior Notes Issued in 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan interest rate	8.00%		8.00%
Discount Rate | Compound Embedded Derivative With Second Lien Facility Agreement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.11	0.13