Fair Value of Financial Instruments - Equity Interest in Related Party and Related Loans Measured at Fair Value on Recurring Basis (Detail) $ in Thousands	Sep. 30, 2018 USD ($)
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Fair Value	$ 223,373
Original Cost	232,260
Fair Value Measurements, Recurring [Member] \| Equity Method Investment and Other Loans [Member] \| Other Loans and Other Assets [Member]
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Fair Value	108,373
Original Cost	117,260
Fair Value Measurements, Recurring [Member] \| Mortgage Loans [Member] \| Mortgage Loans [Member]
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Fair Value	115,000
Original Cost	$ 115,000

Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant