Commercial Group Land Sales (Details Textual) (USD $)		3 Months Ended			3 Months Ended
	Jan. 31, 2011 Parcel	Oct. 31, 2011 6 acre land parcel and air rights - Parcel 1 [Member]	Apr. 30, 2011 6 acre land parcel and air rights - Parcel 1 [Member]	Jan. 31, 2011 6 acre land parcel and air rights - Parcel 1 [Member]	Apr. 30, 2012 10 acre land parcel and air rights - Parcel 2 [Member]	Jan. 31, 2012 10 acre land parcel and air rights - Parcel 2 [Member]	Jan. 31, 2011 10 acre land parcel and air rights - Parcel 2 [Member]
Commercial Group Land Sales (Textual) [Abstract]
Sales price of land parcel and air rights				$ 45,000,000			$ 40,000,000
Cash deposit received				8,550,000		7,000,000
Amount of purchase price received		2,500,000	33,950,000		33,000,000
Gain on sale of land parcel and air rights			$ 42,622,000		$ 36,484,000
Commercial Group Land Sales (Additional Textual) [Abstract]
Number of parcel of land and air rights sold	2