Acquisitions and Divestitures - Pro Forma (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended			3 Months Ended																12 Months Ended					9 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	Jul. 31, 2013 Nonvoting Common Stock [Member]		Apr. 30, 2013 Nonvoting Common Stock [Member]		Jan. 31, 2013 Nonvoting Common Stock [Member]		Oct. 31, 2012 Nonvoting Common Stock [Member]		Jul. 31, 2012 Nonvoting Common Stock [Member]		Apr. 30, 2012 Nonvoting Common Stock [Member]		Jan. 31, 2012 Nonvoting Common Stock [Member]		Oct. 31, 2011 Nonvoting Common Stock [Member]		Jul. 31, 2013 Nonvoting Common Stock [Member]		Jul. 31, 2012 Nonvoting Common Stock [Member]		Jul. 31, 2011 Nonvoting Common Stock [Member]	Apr. 30, 2012 Precision Dynamics Corporation [Member]	Jul. 31, 2013 Precision Dynamics Corporation [Member]	Jul. 31, 2013 Pro Forma [Member]	Jul. 31, 2012 Pro Forma [Member]
Business Acquisition [Line Items]
Total inventories	$ 16,788								$ 16,788																								$ 1,530	$ 1,530
Interest Expense									16,641	19,090	22,124																						1,402	529
Income Tax Expense (Benefit)																																	2,526	429
Business Combination, Acquisition Related Costs																																	3,600	3,600
Net sales	309,097	300,971	271,175	270,866	269,089	271,151	255,052	273,396	1,152,109	1,068,688	1,059,355																							102,329
Net sales, pro forma									1,220,534	1,238,554
Income (Loss) from Continuing Operations Attributable to Parent									(140,816)	102,471	105,957																	(141,054)		102,242		105,734
(Loss) earnings from continuing operations, pro forma									(136,517)	102,993
Income (Loss) from Continuing Operations, Per Basic Share												$ (3.41)	[1]	$ 0.41	[1]	$ (0.22)	[1]	$ 0.50	[1]	$ 0.40		$ 0.52		$ 0.50		$ 0.53		$ (2.75)	[1]	$ 1.95		$ 2.01
Basic net (loss) income per Class A Common Share, pro forma (USD per share)									$ (2.66)	$ 1.96
Income (Loss) from Continuing Operations, Per Diluted Share												$ (3.41)	[1]	$ 0.41	[1]	$ (0.22)	[1]	$ 0.50	[1]	$ 0.40	[1]	$ 0.51	[1]	$ 0.50	[1]	$ 0.52	[1]	$ (2.75)	[1]	$ 1.94	[1]	$ 1.99
Diluted net (loss) income per Class A Common Share, pro forma (USD per share)									$ (2.66)	$ 1.95
Amortization of Intangible Assets									$ 17,148	$ 10,576	$ 15,571																								$ 5,215	$ 12,517

[1] The sum of the quarters does not equal the year-to-date total for fiscal 2013 and fiscal 2012 due to the quarterly changes inweighted-average shares outstanding.