Commitments and Contingencies (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Contingent rent percentage	11.50%
Lease expiration date	Jan. 19, 2027
Number of optional renewal terms	3
Optional renewal term in years	10 years
Lease expense, excluding executory costs	$ 34.0	$ 30.7	$ 22.1
Holland Creek Metropolitan District [Member]
Credit-enhanced bonds issued amount	8.0
Amount outstanding in letters of credit	8.1
Red Sky Ranch Metropolitan District [Member]
Other long-term liabilities	1.8
Estimated cessation date of capital improvement fee payment obligation	July 31, 2028
Various Other [Member]
Amount outstanding in letters of credit	59.5
Employee Housing Bonds [Member]
Amount outstanding in letters of credit	53.4
Workers' Compensation and General Liability Related to Construction and Development Activities [Member]
Amount outstanding in letters of credit	$ 4.3
Maximum [Member]
Annual base rent rate	11.00%
Minimum [Member]
Annual base rent rate	10.25%