v3.19.3.a.u2
Goodwill - impairments (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2019
Dec. 31, 2018
Nov. 30, 2018
Goodwill, Impaired [Abstract]        
Goodwill $ 21.3 $ 21.3 $ 21.3  
Amount of carrying value in excess of fair value   0.0 0.0  
Curtis Palmer        
Goodwill, Impaired [Abstract]        
Goodwill 14.4 14.4 14.4  
Fair value in excess of carrying value       $ 8.3
Fair value in excess of carrying value (as a percent)       9.00%
Impairment of goodwill 14.7      
Morris And Nipigon        
Goodwill, Impaired [Abstract]        
Fair value in excess of carrying value $ 111.7      
Fair value in excess of carrying value (as a percent) 118.00%      
Impairment of goodwill $ 0.0      
Morris        
Goodwill, Impaired [Abstract]        
Goodwill 3.3 3.3 3.3  
Nipigon        
Goodwill, Impaired [Abstract]        
Goodwill $ 3.6 $ 3.6 $ 3.6