Aggregate par or stated value of issued nonredeemable common stock (or common stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable common shares, par value and other disclosure concepts are in another section within stockholders' equity.

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Carrying amount of the equity interests owned by noncontrolling preferred unit holders in an entity included in the reporting entity's consolidated financial statements.

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Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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Carrying amount, attributable to parent, of an entity's issued and outstanding stock which is not included within permanent equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. Includes stock with a put option held by an ESOP and stock redeemable by a holder only in the event of a change in control of the issuer.

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BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Revisions on the Financial Statements (Details) - USD ($) $ in Thousands	Jul. 31, 2018	Apr. 30, 2018	Jul. 31, 2017	Apr. 30, 2017
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Common shares of beneficial interest	$ 899,708	$ 900,097
Noncontrolling interests - consolidated real estate entities	7,376	8,888
Redeemable noncontrolling interests - consolidated real estate entities	6,230	6,644
Equity	677,727	687,563	$ 602,004	$ 636,158
Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Common shares of beneficial interest		907,843
Noncontrolling interests - consolidated real estate entities		1,078
Redeemable noncontrolling interests - consolidated real estate entities		6,708
Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Common shares of beneficial interest		(7,746)
Noncontrolling interests - consolidated real estate entities		7,810
Redeemable noncontrolling interests - consolidated real estate entities		(64)
Common Stock [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity	899,708	900,097	905,409	908,905
Common Stock [Member] \| Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity		907,843	912,625	916,121
Common Stock [Member] \| Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity		(7,746)	(7,216)	(7,216)
Noncontrolling Interest [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity	$ 78,766	81,900	73,773	82,437
Noncontrolling Interest [Member] \| Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity		74,090	66,493	75,157
Noncontrolling Interest [Member] \| Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Equity		$ 7,810	$ 7,280	$ 7,280