Stockholders' Equity (Schedule of Dividend Increases) (Details) (USD $)	1 Months Ended							3 Months Ended	1 Months Ended
	Jul. 30, 2013	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011	Jul. 30, 2013 Quarterly [Member]	Apr. 30, 2013 Quarterly [Member]	Apr. 30, 2012 Quarterly [Member]	Mar. 31, 2011 Quarterly [Member]	Jul. 30, 2013 Annual [Member]	Apr. 30, 2013 Annual [Member]	Apr. 30, 2012 Annual [Member]	Apr. 30, 2011 Annual [Member]
Schedule of Dividend Increases [Line Items]
Common stock, dividends, rate increase, percent	100.00%	20.00%	25.00%	20.00%
Common stock, dividends, per share, declared					$ 0.18	$ 0.09	$ 0.075	$ 0.06	$ 0.72	$ 0.36	$ 0.3	$ 0.24