Summary of Significant Accounting Policies - Dividends (Details) - USD ($) $ in Thousands	9 Months Ended
	Jan. 22, 2016	Jan. 23, 2015
Accounting Policies [Abstract]
Cash dividends paid to common stockholders	$ 21,132	$ 21,711
Dividend equivalent rights	307	276
Total dividends	$ 21,439	$ 21,987