Fair Value of Financial Instruments - Equity Interest in Related Party and Related Loans Measured at Fair Value on Recurring Basis (Detail) $ in Thousands	Jun. 30, 2018 USD ($)
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Fair Value	$ 225,672
Original Cost	232,666
Fair Value Measurements, Recurring [Member] \| Equity Method Investments and Other Loans [Member] \| Other Loans and Other Assets [Member]
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Fair Value	110,672
Original Cost	117,666
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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-SubTopic 210
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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