Notes and Contracts Payable (Schedule of Notes and Contracts Payable) (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Other notes and contracts payable with maturities through 2029, weighted -average interest rates of 3.77% and 3.41%	$ 11.0	$ 4.2
Debt And Capital Lease Obligations Before Discounts Premiums Debt Issuance Costs	1,561.0	1,404.2
Unamortized discounts and debt issuance costs	(14.4)	(10.3)
Notes and contracts payable net of unamortized discount and debt issuance costs	1,546.6	1,393.9
5.45% unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes	450.0	0.0
2.40% unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes	650.0	650.0
4.00% unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes	450.0	450.0
4.60% unsecured notes
Debt Instrument [Line Items]
Senior unsecured notes	$ 0.0	$ 300.0