Annual report pursuant to Section 13 and 15(d)

401(k) Plan (Details)

v3.20.4
401(k) Plan (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Contractors [Abstract]      
Defined contribution plan expense $ 5.9 $ 5.5 $ 5.9