XML 71 R54.htm IDEA: XBRL DOCUMENT v3.20.4
Summary of Significant Accounting Policies, Advertising Expenses (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Advertising Expense [Abstract]      
Advertising costs incurred $ 14.7 $ 16.3 $ 19.1