Leases - Lease Costs and Assumptions (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Leases [Abstract]    
Operating lease cost $ 4.0 $ 3.1
Short-term lease cost 1.3 1.5
Variable lease cost $ 1.2 $ 2.1