Fair Value Measurements - Trust's Assets Measured at Fair Value on a Non-Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	$ 36,369
Assets Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	2,356
Investments in Real Estate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	22,556
Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	11,457
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] | Assets Held for Sale [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
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] | 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] | 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 Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value disclosure, nonrecurring	36,369
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
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	22,556
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	$ 11,457