SEGMENT REPORTING (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012	Oct. 31, 2011	Apr. 30, 2012	Apr. 30, 2011
SEGMENT REPORTING [Abstract]
Number of reportable segments			5
Segment revenues and net operating income [Abstract]
Real estate revenue	$ 64,943	$ 60,200	$ 126,929	$ 119,364
Real estate expenses	24,804	25,527	49,645	50,169
Gain on Business Interruption Insurance Recovery	2,263	0	2,263	0
Net operating income	42,402	34,673	79,547	69,195
Depreciation/amortization	(16,506)	(14,874)	(32,728)	(29,682)
Administrative, advisory and trustee services	(2,061)	(2,104)	(4,157)	(4,285)
Other expenses	(513)	(835)	(1,032)	(1,150)
Interest expense	(16,300)	(16,193)	(32,723)	(31,978)
Interest and other income	203	213	345	366
Income from continuing operations	7,225	880	9,252	2,466
Income from discontinued operations	2,785	611	2,754	598
Net income	10,010	1,491	12,006	3,064
Segment Assets [Abstract]
Property owned	1,983,978		1,983,978		1,892,009
Less accumulated depreciation	(394,256)		(394,256)		(373,490)
Total property owned	1,589,722		1,589,722		1,518,519
Real Estate Held-for-sale	1,844		1,844		2,067
Cash and cash equivalents	84,258	32,697	84,258	32,697	39,989	41,191
Other investments	637		637		634
Receivables and other assets	107,988		107,988		114,569
Development in progress	23,218		23,218		27,599
Unimproved land	11,670		11,670		10,990
Total Assets	1,819,337		1,819,337		1,714,367
Multi-Family Residential [Member]
Segment revenues and net operating income [Abstract]
Real estate revenue	23,105	17,952	44,314	35,041
Real estate expenses	9,008	8,521	18,301	16,672
Gain on Business Interruption Insurance Recovery	2,263		2,263
Net operating income	16,360	9,431	28,276	18,369
Segment Assets [Abstract]
Property owned	624,159		624,159		539,783
Less accumulated depreciation	(131,193)		(131,193)		(128,834)
Total property owned	492,966		492,966		410,949
Commercial-Office [Member]
Segment revenues and net operating income [Abstract]
Real estate revenue	19,128	18,367	37,767	37,182
Real estate expenses	9,392	8,813	18,682	17,756
Gain on Business Interruption Insurance Recovery	0		0
Net operating income	9,736	9,554	19,085	19,426
Segment Assets [Abstract]
Property owned	608,125		608,125		605,318
Less accumulated depreciation	(129,495)		(129,495)		(121,422)
Total property owned	478,630		478,630		483,896
Commercial-Medical [Member]
Segment revenues and net operating income [Abstract]
Real estate revenue	15,517	17,073	30,844	33,690
Real estate expenses	4,183	5,971	8,266	11,489
Gain on Business Interruption Insurance Recovery	0		0
Net operating income	11,334	11,102	22,578	22,201
Segment Assets [Abstract]
Property owned	502,222		502,222		500,268
Less accumulated depreciation	(85,902)		(85,902)		(78,744)
Total property owned	416,320		416,320		421,524
Commercial-Industrial [Member]
Segment revenues and net operating income [Abstract]
Real estate revenue	3,577	3,566	7,037	7,001
Real estate expenses	935	1,135	1,955	2,101
Gain on Business Interruption Insurance Recovery	0		0
Net operating income	2,642	2,431	5,082	4,900
Segment Assets [Abstract]
Property owned	119,511		119,511		119,002
Less accumulated depreciation	(22,133)		(22,133)		(20,693)
Total property owned	97,378		97,378		98,309
Commercial-Retail [Member]
Segment revenues and net operating income [Abstract]
Real estate revenue	3,616	3,242	6,967	6,450
Real estate expenses	1,286	1,087	2,441	2,151
Gain on Business Interruption Insurance Recovery	0		0
Net operating income	2,330	2,155	4,526	4,299
Segment Assets [Abstract]
Property owned	129,961		129,961		127,638
Less accumulated depreciation	(25,533)		(25,533)		(23,797)
Total property owned	$ 104,428		$ 104,428		$ 103,841