Investment Securities (Schedule of Unrealized Holding Gain (Loss) on Investments) (Details) - USD ($) $ in Thousands	9 Months Ended
	Feb. 25, 2017	Feb. 27, 2016
Gain (Loss) on Investments [Line Items]
Unrealized holding gains (losses), net of tax on available-for-sale securities	$ 124	$ (834)
Current Assets
Gain (Loss) on Investments [Line Items]
Unrealized holding gains (losses), net of tax on available-for-sale securities	(30)	(740)
Noncurrent Assets
Gain (Loss) on Investments [Line Items]
Unrealized holding gains (losses), net of tax on available-for-sale securities	$ 154	$ (94)