QUARTERLY RESULTS FROM CONTINUING OPERATIONS (UNAUDITED) (Details) (USD $)	3 Months Ended								12 Months Ended
	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011
Unaudited quarterly results of continuing operations
Revenues	$ 417,089,000	$ 442,708,000	$ 670,752,000	$ 357,468,000	$ 406,963,000	$ 445,170,000	$ 663,762,000	$ 350,983,000	$ 1,888,016,000	$ 1,866,878,000	$ 1,742,563,000
Gross margin	221,582,000	232,847,000	339,651,000	190,335,000	209,885,000	228,193,000	335,512,000	187,674,000	984,414,000	961,265,000	880,095,000
(Loss) earnings from continuing operations	(7,984,000)	5,052,000	41,208,000	(28,265,000)	(19,665,000)	(4,440,000)	28,930,000	(31,720,000)	10,012,000	(26,896,000)	(112,042,000)
(Loss) earnings per basic share from continuing operations (in dollars per share)	$ (0.25)	$ 0.16	$ 1.27	$ (0.88)	$ (0.61)	$ (0.14)	$ 0.90	$ (0.99)	$ 0.31	$ (0.84)	$ (3.49)
(Loss) earnings per diluted share from continuing operations (in dollars per share)	$ (0.25)	$ 0.13	$ 1.02	$ (0.88)	$ (0.61)	$ (0.14)	$ 0.78	$ (0.99)	$ 0.24	$ (0.84)	$ (3.49)
De Beers settlement		300,000		1,900,000					2,191,000
Costs incurred related to the debt refinancing transactions					$ 5,000,000