XML 84 R70.htm IDEA: XBRL DOCUMENT v3.20.2
Employee benefit plans - Defined Contribution Plan (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Employee benefit plans        
Defined contribution expense $ 3.5 $ 3.0 $ 10.1 $ 9.0