Cash and Marketable Securities - Textual (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash and Cash Equivalents [Abstract]
Restricted marketable securities	$ 82.2	$ 72.6
Unrealized net gain (loss) on marketable securities	$ 0.6	$ 0.4	$ 1.2