XML 45 R62.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Cash and Marketable Securities - Textual (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Cash and Cash Equivalents [Abstract]    
Restricted marketable securities $ 76.1 $ 62.0
Unrealized net gain (loss) on marketable securities $ 1.2 $ (1.7)