Investment in Unconsolidated Ventures - Summarized Balance Sheet Information (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Sep. 30, 2018
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Equity Method Investment, Summarized Financial Information, Assets	$ 15.3	$ 27.5
Equity Method Investment, Summarized Financial Information, Liabilities and Equity [Abstract]
Equity Method Investment, Summarized Financial Information, Liabilities and Equity	15.3	27.5
Investment in unconsolidated ventures	7.3	11.7
Cash and cash equivalents
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Equity Method Investment, Summarized Financial Information, Assets	1.6	10.2
Real estate
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Equity Method Investment, Summarized Financial Information, Assets	13.6	17.2
Other assets
Equity Method Investment, Summarized Financial Information, Assets [Abstract]
Equity Method Investment, Summarized Financial Information, Assets	0.1	0.1
Accounts Payable and Accrued Liabilities [Member]
Equity Method Investment, Summarized Financial Information, Liabilities and Equity [Abstract]
Equity Method Investment, Summarized Financial Information, Liabilities	0.3	0.6
Equity
Equity Method Investment, Summarized Financial Information, Liabilities and Equity [Abstract]
Equity Method Investment Summarized Financial Information, Equity	$ 15.0	$ 26.9

The amount of assets reported by an equity method investment of the entity.

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Amount of equity, including noncontrolling interest, reported by an equity method investment of the entity.

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The amount of liabilities reported by an equity method investment of the entity.

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The amount of liabilities and equity reported by an equity method investment of the entity.

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This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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