Fair Value of Financial Instruments - Equity Interest in Related Party and Related Loans Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financial Instruments Measured At Fair Value On Recurring Basis [Line Items]
Fair Value	$ 115,000	$ 229,554
Original Cost	115,000	233,354
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	115,000
Original Cost	$ 115,000	115,000
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		114,554
Original Cost		$ 118,354

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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-Publisher FASB
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
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Name:	us-gaap_InvestmentOwnedAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant