Buildings and Equipment (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
ORIGINAL COST	$ 1,250.0	$ 1,221.1
ACCUMULATED DEPRECIATION	749.5	732.4
NET BOOK VALUE	500.5	488.7
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	224.7	217.6
ACCUMULATED DEPRECIATION	137.7	136.5
NET BOOK VALUE	87.0	81.1
Equipment
Property, Plant and Equipment [Line Items]
ORIGINAL COST	499.7	478.4
ACCUMULATED DEPRECIATION	281.9	275.4
NET BOOK VALUE	217.8	203.0
Leasehold Improvements
Property, Plant and Equipment [Line Items]
ORIGINAL COST	514.1	513.6
ACCUMULATED DEPRECIATION	329.6	320.2
NET BOOK VALUE	$ 184.5	$ 193.4