Notes Payable - Narrative (Details) - Notes Payable to Banks - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Debt
Weighted average interest rate (as a percent)	3.90%		3.90%
Weighted average remaining years until maturity (in years)			6 years 4 months 24 days
Interest incurred on notes and bonds	$ 229.4	$ 206.1	$ 449.3	$ 406.6
3.875% Notes due 2025
Debt
Repayments of long-term debt			$ 500.0
Stated interest rate (as a percent)	3.875%		3.875%
Maximum
Debt
Debt to total adjusted assets ratio (as a percent)			60.00%
Secured debt to total adjusted assets ratio (as a percent)			40.00%
Minimum
Debt
Debt service coverage ratio			1.5
Total unencumbered assets as a percentage of outstanding unsecured debt (as a percent)			150.00%