Stock Split (Details Textual) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Jul. 31, 2012	Jul. 26, 2012 After Amendment [Member] Common Class A [Member]	Jul. 26, 2012 After Amendment [Member] Common Class B [Member]	Jul. 26, 2012 Before Amendment [Member] Common Class A [Member]	Jul. 26, 2012 Before Amendment [Member] Common Class B [Member]
Stock Split (Textual) [Abstract]
Stock split	Authorized a 3-for-2 stock split for outstanding shares of the Company’s Class A and Class B common stock
Common stock, shares authorized		85,000,000	400,000,000	57,000,000	100,000,000
Value of shares issued in the stock split	$ 10.7
Par value per share of the shares issued in the stock split	$ 0.15