Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Numerator:
Net income	$ 240.9	$ 239.9
Denominator:
Weighted average outstanding shares - basic (in shares)	46.3	45.2
Effect of dilutive securities:
Stock options, RSUs, and ESPP (in shares)	3.3	2.5
Weighted average shares - diluted (in shares)	49.6	47.7
Net income per common share:
Basic (in dollars per share)	$ 5.20	$ 5.31
Diluted (in dollars per share)	$ 4.86	$ 5.03
Stock options and restricted stock units excluded from calculation (in shares)	0.1	0.0