Stock-based compensation - other information (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Other information about options outstanding
Shares authorized	23.5
Shares available for future issuance	27.0
Tax benefit of options exercised	$ 10.3	$ 30.0	$ 32.6
Restricted Stock or Unit Expense	$ 7.3	$ 7.4	$ 5.1