XML 54 R39.htm IDEA: XBRL DOCUMENT v3.20.4
Summary of Significant Accounting Policies - Research and Development - Narrative (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Accounting Policies [Abstract]      
Research and development costs $ 11.6 $ 11.9 $ 11.1