Segment Reporting (Details) (USD $)	3 Months Ended				6 Months Ended
	Jan. 31, 2013		Jan. 31, 2012		Jan. 31, 2013		Jan. 31, 2012
United States [Member]
Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Line Items]
Revenue	$ 21,888,000	[1]	$ 24,516,000	[2]	$ 45,978,000	[1]	$ 52,946,000	[2]
Gross Long-Lived Assets	29,983,000		26,014,000		29,983,000		26,014,000
Foreign Countries [Member]
Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Line Items]
Revenue	14,263,000	[1]	15,657,000	[2]	26,995,000	[1]	29,539,000	[2]
Gross Long-Lived Assets	5,507,000		5,323,000		5,507,000		5,323,000
Peru [Member]
Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Line Items]
Revenue	2,200,000		5,500,000		5,800,000		10,100,000
Brazil [Member]
Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Line Items]
Revenue	3,700,000		3,600,000		7,800,000		6,900,000
Chile [Member]
Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Line Items]
Revenue	$ 3,200,000		$ 2,200,000		$ 5,800,000		$ 4,600,000

[1] Significant foreign revenues include revenues in Peru ($2.2 million and $5.8 million for the three and six months ended January 31, 2013, respectively), Brazil ($3.7 million and $7.8 million for the three and six months ended January 31, 2013, respectively) and Chile ($3.2 million and $5.8 million for the three and six months ended January 31, 2013, respectively).

[2] Significant foreign revenues include revenues in Peru ($5.5 million and $10.1 million for the three and six months ended January 31, 2012, respectively), Brazil ($3.6 million and $6.9 million for the three and six months ended January 31, 2012, respectively) and Chile ($2.2 million and $4.6 million for the three and six months ended January 31, 2012, respectively).