CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) (Parenthetical) (USD $) In Thousands, except Share data	Jul. 31, 2011	Apr. 30, 2011
Real estate investments
Mortgage loans receivable, net of allowance (in dollars)	$ 3	$ 3
Other assets
Receivable arising from straight-lining of rents, net of allowance (in dollars)	1,017	996
Accounts receivable, net of allowance (in dollars)	220	317
Intangible assets, net of accumulated amortization (in dollars)	43,877	42,154
Property and equipment, net of accumulated depreciation (in dollars)	1,358	1,231
Deferred charges and leasing costs, net of accumulated amortization (in dollars)	14,615	13,675
EQUITY
Preferred Shares of Beneficial Interest, no par value (in dollars per share)	$ 0.0000	$ 0.0000
Preferred Shares of Beneficial Interest, shares issued (in shares)	1,150,000	1,150,000
Preferred Shares of Beneficial Interest, shares outstanding (in shares)	1,150,000	1,150,000
Preferred Shares of Beneficial Interest, aggregate liquidation preference (in dollars)	$ 28,750,000	$ 28,750,000
Common Shares of Beneficial Interest, no par value (in dollars per share)	$ 0.0000	$ 0.0000
Common Shares of Beneficial Interest, shares issued (in shares)	81,258,846	80,523,265
Common Shares of Beneficial Interest, shares outstanding (in shares)	81,258,846	80,523,265
Noncontrolling interests - Operating Partnership (in shares)	19,958,439	20,067,350