Earnings Per Share - Summary of Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Numerator (in millions):
Net income available to common stockholders	$ 33.2	$ 36.5
Denominator (in thousands):
Weighted average common shares outstanding	24,801	24,791
Dilutive effect of stock options and awards	161	165
Denominator for diluted earnings per share	24,962	24,956
Net income per share, basic:	$ 1.34	$ 1.47
Net income per share, diluted:	$ 1.33	$ 1.46