Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Balances at Jul. 31, 2013	$ 762,401	$ 13	$ 368,769	$ (47,161)	$ 440,780
Balances (in shares) at Jul. 31, 2013		125,494,995
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	178,687	$ 0	0	0	178,687
Currency translation adjustment	26,428	0	0	26,428	0
Interest rate swap, net of tax effects	673	0	0	673	0
Exercise of stock options, net of repurchased shares	9,886	$ 0	10,349	0	(463)
Exercise of stock options, net of repurchased shares (in shares)		566,404
Employee stock-based compensation and related tax benefit	23,085	$ 0	23,085	0	0
Shares issued for Employee Stock Purchase Plan	2,339	$ 0	2,339	0	0
Shares issued for Employee Stock Purchase Plan (in shares)		81,967
Balances at Jul. 31, 2014	1,003,499	$ 13	404,542	(20,060)	619,004
Balances (in shares) at Jul. 31, 2014		126,143,366
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	219,783	$ 0	0	0	219,783
Currency translation adjustment	(49,518)	0	0	(49,518)	0
Interest rate swap, net of tax effects	785	0	0	785	0
Exercise of stock options, net of repurchased shares	684	$ 0	2,193	0	(1,509)
Exercise of stock options, net of repurchased shares (in shares)		397,520
Employee stock-based compensation and related tax benefit	19,636	$ 0	19,636	0	0
Shares issued for Employee Stock Purchase Plan	3,079	$ 0	3,079	0	0
Shares issued for Employee Stock Purchase Plan (in shares)		101,015
Shares repurchased	(233,484)	$ (1)	(21,642)	0	(211,841)
Shares repurchased (in shares)		(6,485,561)
Balances at Jul. 31, 2015	964,464	$ 12	407,808	(68,793)	625,437
Balances (in shares) at Jul. 31, 2015		120,156,340
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	270,360	$ 0	0	0	270,360
Currency translation adjustment	(40,684)	0	0	(40,684)	0
Interest rate swap, net of tax effects	283	0	0	283	0
Exercise of stock options, net of repurchased shares	(1,114)	$ 0	(372)	0	(742)
Exercise of stock options, net of repurchased shares (in shares)		1,129,440
Employee stock-based compensation and related tax benefit	20,631	$ 0	20,631	0	0
Shares issued for Employee Stock Purchase Plan	3,369	$ 0	3,369	0	0
Shares issued for Employee Stock Purchase Plan (in shares)		108,132
Shares repurchased	(442,853)	$ (1)	(38,991)	0	(403,861)
Shares repurchased (in shares)		(11,271,852)
Balances at Jul. 31, 2016	$ 774,456	$ 11	$ 392,445	$ (109,194)	$ 491,194
Balances (in shares) at Jul. 31, 2016		110,122,060