Stock-based compensation - Stock Option Grants, Vesting, and Exercises (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Weighted-average fair value per share of stock options granted (in dollars per share)	$ 40.34	$ 31.86	$ 26.50
Total grant date fair value of stock options vested	$ 2.7	$ 3.2	$ 2.7
Total intrinsic value of stock options exercised	$ 15.2	$ 10.9	$ 11.5