v3.20.4
Goodwill - Carrying Amount of Goodwill (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Goodwill [Roll Forward]    
Goodwill balance, beginning of year $ 311,865 $ 38,019
Goodwill balance, end of year 311,865 311,865
6 River Systems, Inc.    
Goodwill [Roll Forward]    
Increase related to acquisitions 0 264,527
Other acquisitions    
Goodwill [Roll Forward]    
Increase related to acquisitions $ 0 $ 9,319