Accounting Policies (Details Textual 1) (USD $) In Millions, unless otherwise specified	Jul. 31, 2012
Variable Interest Entity [Line Items]
Maximum Loss Exposure for Unconsolidated Variable Interest Entities	$ 66
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	$ 29
Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of Variable Interest Entities	31
Number of Properties Representing Variable Interest Entities	20
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of Variable Interest Entities	59
Residential Group [Member] | Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of Variable Interest Entities	16
Number of Properties Representing Variable Interest Entities	7
Commercial Group [Member] | Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of Variable Interest Entities	14
Number of Properties Representing Variable Interest Entities	12
Land Development Group [Member] | Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of Variable Interest Entities	1