Summary of Significant Accounting Policies - Dividends (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 24, 2015	Jul. 25, 2014
Accounting Policies [Abstract]
Cash dividends paid to common stock holders	$ 7,028	$ 7,224
Dividend equivalent rights	124	91
Total dividends	$ 7,152	$ 7,315