Fair Value Measurements - Trust's Assets Measured at Fair Value on a Non-Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	$ 36,484
Investments in Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	22,623
Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	11,505
Assets Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	2,356
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Investments in Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Assets Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	0
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	0
Significant Other Observable Inputs (Level 2) [Member] | Investments in Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	0
Significant Other Observable Inputs (Level 2) [Member] | Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	0
Significant Other Observable Inputs (Level 2) [Member] | Assets Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	0
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	36,484
Significant Unobservable Inputs (Level 3) [Member] | Investments in Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	22,623
Significant Unobservable Inputs (Level 3) [Member] | Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	11,505
Significant Unobservable Inputs (Level 3) [Member] | Assets Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	$ 2,356