Components of Comprehensive Income (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 45.6	$ 36.1	$ 102.4	$ 61.6
Other comprehensive income (loss)
Derivative contracts increase (decrease)	2.2	(0.4)	21.7	8.9
Total comprehensive income	$ 47.8	$ 35.7	$ 124.1	$ 70.5