Buildings and Equipment (Detail) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Property, Plant and Equipment [Line Items]
ORIGINAL COST	$ 1,325.4	$ 1,331.1
ACCUMULATED DEPRECIATION	860.8	840.8
NET BOOK VALUE	464.6	490.3
Land and Improvements
Property, Plant and Equipment [Line Items]
ORIGINAL COST	11.5	11.5
ACCUMULATED DEPRECIATION	0.3	0.3
NET BOOK VALUE	11.2	11.2
Buildings
Property, Plant and Equipment [Line Items]
ORIGINAL COST	227.8	226.5
ACCUMULATED DEPRECIATION	140.0	143.4
NET BOOK VALUE	87.8	83.1
Equipment
Property, Plant and Equipment [Line Items]
ORIGINAL COST	512.0	539.6
ACCUMULATED DEPRECIATION	335.3	343.4
NET BOOK VALUE	176.7	196.2
Leasehold Improvements
Property, Plant and Equipment [Line Items]
ORIGINAL COST	574.1	553.5
ACCUMULATED DEPRECIATION	385.2	353.7
NET BOOK VALUE	$ 188.9	$ 199.8