Consolidated Statements of Changes in Shareholders' Equity (Parentheticals) (USD $)	3 Months Ended
	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2010
Statement Of Stockholders Equity [Abstract]
Dividends declared per share (in dollars per share)	$ 0.15	$ 0.15	$ 0.15	$ 0.15	$ 0.15	$ 0.15	$ 0.20	$ 0.20	$ 0.20	$ 0.20	$ 2.00	$ 0.20