Impairment Charges and Reserves - Summary of Significant Unobservable Inputs (Detail)	3 Months Ended
Mar. 31, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Consolidated Assets, Fair Value	$ 201,100,000
Preferred Equity Interests, Fair Value	232,000,000
Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Consolidated Assets, Fair Value	201,100,000
Preferred Equity Interests, Fair Value	232,000,000
Level 3 [Member] \| Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Consolidated Assets, Fair Value	201,100,000
Preferred Equity Interests, Fair Value	232,000,000
Impairment of Consolidated Assets [Member] \| Level 3 [Member] \| Indicative Bid/Contracted Price [Member] \| Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Consolidated Assets, Fair Value	92,100,000
Impairment of Consolidated Assets [Member] \| Level 3 [Member] \| Income Capitalization/Sales Comparison Approach [Member] \| Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Consolidated Assets, Fair Value	$ 109,000,000
Market capitalization rate	7.40%
Reserve of Preferred Equity Interests [Member] \| Level 3 [Member] \| Discounted Cash Flow [Member] \| Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Equity Interests, Fair Value	$ 232,000
NOI growth rate	1.00%
Reserve of Preferred Equity Interests [Member] \| Level 3 [Member] \| Discounted Cash Flow [Member] \| Fair Value Measurements [Member] \| Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	8.40%
Terminal capitalization rate	7.90%
Reserve of Preferred Equity Interests [Member] \| Level 3 [Member] \| Discounted Cash Flow [Member] \| Fair Value Measurements [Member] \| Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	9.00%
Terminal capitalization rate	8.50%

Fair value inputs NOI growth rate.

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- Definition

Fair value inputs terminal cap rate.

+ References

No definition available.

+ Details

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- Definition

Fair value of preferred equity interests.

+ References

No definition available.

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- Definition

Fair value of long lived assets held and used and held for sale.

+ References

No definition available.

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- Definition

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.

+ References

No definition available.

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- Definition

Ratio of the net operating income produced by an asset and its capital cost (original prices paid to buy the asset), used as an input to measure fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

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