Loans Receivable, Net - Property Type and Geographic Distribution of Properties Securing Loans in Portfolio (Parenthetical) (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loan exposure including senior interests	$ 533.4	$ 446.9
2018 Single Asset Securitization [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Single asset securitization principal amount	$ 993.5	$ 1,000.0	$ 1,000.0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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