Commitments and Contingencies - Defined Contribution Plan (Details) - USD ($)
$ in Millions
1 Months Ended 12 Months Ended
Jan. 31, 2018
Dec. 31, 2018
Commitments and Contingencies    
Employer matching contribution (as a percent) 50.00%  
Percentage of employee's gross pay match 6.00%  
Company matching contribution   $ 0.2