Stockholders' Equity (Details) - USD ($)	3 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Dec. 09, 2015	Dec. 08, 2015	Sep. 28, 2015
Stock Repurchase Program
Stock repurchase program, remaining authorized repurchase amount	$ 8,664,000
Maximum amount authorized by the Board of Directors for repurchases of the Company's common stock	$ 100,000,000
Treasury Stock, Shares, Acquired	0	0
Dividends
Targeted annual dividend per share (in dollars per share)	$ 1.20
Subsequent Event [Member]
Stock Repurchase Program
Stock repurchase program, remaining authorized repurchase amount				$ 8,664,000
Quarterly Dividend - First
Dividends
Quarterly dividend payment amount per share (in dollars per share)					$ 0.30
Quarterly Dividend - Second | Subsequent Event [Member]
Dividends
Quarterly dividend payment amount per share (in dollars per share)			$ 0.30