Stock Plans - Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Stock Plans
Compensation cost on stock-based compensation plans	$ 3.7	$ 3.3	$ 11.1	$ 8.9