Stockholders' Equity (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	4 Months Ended
	Jan. 21, 2018	Jan. 22, 2017
Equity, Class of Treasury Stock [Line Items]
Cash dividends declared per common share	$ 0.40	$ 0.40
Dividends, common stock	$ 11.8
Expiration: November 2018
Equity, Class of Treasury Stock [Line Items]
Repurchase of common stock, remaining authorized amount	$ 181.0