XML 73 R37.htm IDEA: XBRL DOCUMENT v3.20.4
Organization and Significant Accounting Policies, Deferred Revenue (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Deferred Revenue [Abstract]    
Revenue recognized from amounts in beginning deferred revenue balance $ 100.4 $ 159.5