Acquisitions - Pro Forma Operating Results (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Jul. 31, 2016		Apr. 30, 2016		Jan. 31, 2016		Oct. 31, 2015		Jul. 31, 2015		Apr. 30, 2015		Jan. 31, 2015		Oct. 31, 2014		Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Business Acquisition [Line Items]
Net sales	$ 282,106		$ 286,816		$ 268,630		$ 283,073		$ 288,636		$ 290,227		$ 282,628		$ 310,240		$ 1,120,625	$ 1,171,731	$ 1,225,034
(Loss) earnings from continuing operations, as reported	$ 25,136		$ 20,981		$ 15,290		$ 18,703		$ (39,394)		$ 17,213		$ 11,584		$ 15,499		80,110	4,902	(48,146)
Nonvoting Common Stock [Member]
Business Acquisition [Line Items]
(Loss) earnings from continuing operations, as reported																	$ 80,110	$ 4,902	$ (48,238)
Basic (loss) earnings from continuing operations per Class A Common Share, as reported	$ 0.50	[1]	$ 0.42	[1]	$ 0.30	[1]	$ 0.37	[1]	$ (0.77)	[1]	$ 0.34	[1]	$ 0.23	[1]	$ 0.30	[1]	$ 1.59	$ 0.10	$ (0.93)
Diluted (loss) earnings from continuing operations per Class A Common Share, as reported	$ 0.49	[1]	$ 0.42	[1]	$ 0.30	[1]	$ 0.37	[1]	$ (0.77)	[1]	$ 0.33	[1]	$ 0.23	[1]	$ 0.30	[1]	$ 1.58	$ 0.10	$ (0.93)

[1] *** The sum of the quarters does not equal the year-to-date total for fiscal 2015 due to the quarterly changes inweighted-average shares outstanding.