Summary of Significant Accounting and Reporting Policies (Earnings Per Share) (Details) (USD $)	3 Months Ended												12 Months Ended
	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	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, 2014	Jul. 31, 2013	Jul. 31, 2012
Accounting Policies [Abstract]
Net income for basic calculation	$ 7,988,000	$ 5,875,000	$ 5,983,000	$ 5,305,000	$ 5,156,000	$ 2,852,000	$ 2,365,000	$ 7,435,000	$ 7,928,000	$ 6,066,000	$ 5,821,000	$ 12,601,000	$ 25,151,000	$ 17,808,000	$ 32,416,000
Interest expense (net of tax) on 3.0% convertible senior notes													3,394,000	4,468,000	4,468,000
Numerator for diluted calculation													$ 28,545,000	$ 22,276,000	$ 36,884,000
Denominator for basic calculation (in shares)													15,943,000	16,963,000	19,995,000
Dilutive effect on shares of stock-based awards (in shares)													254,000	91,000	228,000
Dilutive effect on shares of conversion of 3.0% convertible senior notes (in shares)													4,709,000	6,010,000	5,768,000
Denominator for diluted calculation (in shares)													20,906,000	23,064,000	25,991,000
Weighted average performance shares outstanding during the period that are excluded from EPS calculation													81,000	39,000	5,000
Reduction in weighted average shares as a result of the repurchase of common shares													1,039,000	453,000	4,350,000
Stock-based Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive equity-classified stock-based awards not included in calculation of diluted earnings per share (in shares)													599,000	2,701,000	2,169,000