CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	Apr. 30, 2018	Apr. 30, 2017
EQUITY
Common Shares of Beneficial Interest, shares issued (in shares)	119,525,975	121,199,299
Common Shares of Beneficial Interest, shares outstanding (in shares)	119,525,975	121,199,299
Noncontrolling interests - Operating Partnership (in shares)	14,099,434	15,617,216
Series B Preferred Stock [Member]
EQUITY
Preferred Shares of Beneficial Interest, shares issued (in shares)	0	4,600,000
Preferred Shares of Beneficial Interest, shares outstanding (in shares)	0	4,600,000
Preferred shares liquidation preference		$ 115,000,000
Series C Preferred Stock [Member]
EQUITY
Preferred Shares of Beneficial Interest, shares issued (in shares)	4,118,460	0
Preferred Shares of Beneficial Interest, shares outstanding (in shares)	4,118,460	0
Preferred shares liquidation preference	$ 102,971,475
Medium-term Notes [Member]
LIABILITIES
Mortgages payable, loan costs	486,000	$ 0
Mortgages [Member]
LIABILITIES
Mortgages payable, loan costs	$ 2,221,000	$ 3,054,000

Number of partnership units held by noncontrolling interests as of the balance sheet date.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Value of the difference between preference in liquidation and the par or stated values of the preferred shares.

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