Employee Benefit Plans - Assumptions For Estimating Fair Value (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	May 12, 2011	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Jul. 31, 2021	Dec. 31, 2020
Employee Benefit Plans
Stock options granted				698,500	174,649
Stock options
Employee Benefit Plans
Number of options outstanding (in shares)		9,165,066		9,165,066			10,284,498
Compensation cost		$ 4.3	$ 1.5	$ 7.6	$ 2.9
Stock options granted				698,500
Assumptions for estimating fair value
Dividend Yield				0.00%
Expected term of options (years)				5 years	6 years
Risk Free interest rate, minimum (as a percent)				0.61%	0.45%
Risk Free interest rate, maximum (as a percent)				1.04%	1.37%
Volatility, minimum (as a percent)				72.46%	64.19%
Volatility, maximum (as a percent)				73.69%	64.80%
the 2011 Plan
Employee Benefit Plans
Compensation cost		$ 11.1	$ 2.5	$ 19.6	$ 5.0
the 2011 Plan | Stock options
Employee Benefit Plans
Maximum number of common stock shares available for issuance	1,000,000	42,400,000		42,400,000
Aggregate number of options granted (in shares)		9,200,000		9,200,000
Expiration period				10 years
Stock options granted	0
the 2011 Plan | Stock options | Minimum
Employee Benefit Plans
Vesting period				1 year
the 2011 Plan | Stock options | Maximum
Employee Benefit Plans
Vesting period				3 years
the 2011 Plan | Employees | Stock options
Employee Benefit Plans
Vesting period				3 years
Expiration period				10 years
the 2011 Plan | Board of Directors | Stock options
Employee Benefit Plans
Vesting period				1 year
2021 Stock Option Incentive Plan
Employee Benefit Plans
Maximum number of common stock shares available for issuance						22,500,000