Subsequent Events (Details) $ / shares in Units, $ in Millions		4 Months Ended		6 Months Ended
	Feb. 19, 2018 $ / shares	Jan. 21, 2018 restaurant $ / shares	Jan. 22, 2017 restaurant $ / shares	Apr. 15, 2018 USD ($)
Subsequent Event [Line Items]
Cash dividends declared per common share | $ / shares		$ 0.40	$ 0.40
Number of Restaurants | restaurant		2,250	2,261
Subsequent Event
Subsequent Event [Line Items]
Cash dividends declared per common share | $ / shares	$ 0.40
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Subsequent Event [Line Items]
Number of Restaurants				50
Minimum [Member]
Subsequent Event [Line Items]
Estimated Pre-Tax Proceeds from Sale to Franchisees | $				$ 25.0
Maximum [Member]
Subsequent Event [Line Items]
Estimated Pre-Tax Proceeds from Sale to Franchisees | $				$ 27.0