Income Taxes - Deferred Taxes Table (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Deferred tax assets:
Real estate	$ 14.2	$ 10.5
Employee benefits	1.9	1.5
Net operating loss carryforwards	1.4	1.7
Accruals not deductible until paid	0.2	0.2
Total deferred tax assets	17.7	13.9
Valuation allowance	(1.2)	(1.5)
Total deferred tax assets, net of valuation allowance	16.5	12.4
Deferred tax liabilities:
Deferral of profit on lot sales	(40.9)	(18.1)
Total deferred tax liabilities	(40.9)	(18.1)
Deferred tax liability, net	$ (24.4)	$ (5.7)