Prior Year Misstatement Correction in the Current Year (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales	$ 517,200	$ 588,500	$ 1,055,200	$ 1,185,000
Cost of sales	346,400	385,400	706,300	772,800
Gross profit	170,800	203,100	348,900	412,200
Operating income	53,700	65,800	109,200	142,800
Earnings before income taxes	49,400	65,400	102,800	142,700
Income taxes	11,400	17,400	26,300	38,800
Net earnings	$ 38,000	$ 48,000	$ 76,500	$ 103,900
Basic earnings per share (in usd per share)	$ 0.28	$ 0.35	$ 0.57	$ 0.75
Diluted earnings per share (in usd per share)	$ 0.28	$ 0.34	$ 0.57	$ 0.74
Comprehensive income	$ 2,800	$ 1,800	$ 29,100	$ 20,800
Accelerated Revenue Recognition
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales		588,500		1,185,000
Cost of sales		385,400		772,800
Gross profit		203,100		412,200
Operating income		65,800		142,800
Earnings before income taxes		65,400		142,700
Income taxes		17,400		38,800
Net earnings		$ 48,000		$ 103,900
Basic earnings per share (in usd per share)		$ 0.35		$ 0.75
Diluted earnings per share (in usd per share)		$ 0.34		$ 0.74
Comprehensive income		$ 1,800		$ 20,800
Accelerated Revenue Recognition | Scenario, Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales		596,900		1,193,400
Cost of sales		391,400		778,800
Gross profit		205,500		414,600
Operating income		68,200		145,200
Earnings before income taxes		67,800		145,100
Income taxes		18,200		39,600
Net earnings		$ 49,600		$ 105,500
Basic earnings per share (in usd per share)		$ 0.36		$ 0.76
Diluted earnings per share (in usd per share)		$ 0.35		$ 0.75
Comprehensive income		$ 3,400		$ 22,400
Accelerated Revenue Recognition | Restatement Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net sales		(8,400)		(8,400)
Cost of sales		(6,000)		(6,000)
Gross profit		(2,400)		(2,400)
Operating income		(2,400)		(2,400)
Earnings before income taxes		(2,400)		(2,400)
Income taxes		(800)		(800)
Net earnings		$ (1,600)		$ (1,600)
Basic earnings per share (in usd per share)		$ (0.01)		$ (0.01)
Diluted earnings per share (in usd per share)		$ (0.01)		$ (0.01)
Comprehensive income		$ (1,600)		$ (1,600)