Benefit Plans - Pension Plans with Accumulated Benefit Obligation or Projected Benefit Obligation in Excess of Plan Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Pension plans with a projected benefit obligation in excess of plan assets:
Projected benefit obligation	$ 83.3	$ 97.5
Fair value of plan assets	27.4	30.5
Pension plans with an accumulated benefit obligation in excess of plan assets:
Projected benefit obligation	83.3	83.5
Fair value of plan assets	27.4	18.8
Accumulated benefit obligation	$ 82.6	$ 81.9