Impairment Of Long-Lived Assets And Other Lease Charges Closed Restaurant Reserve Activity (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Closed-restaurant reserve, beginning of the period	$ 2,028	$ 1,513
Provisions for restaurant closures	162	1,174
Changes in estimates of accrued costs	(120)	81
Payments, net	(746)	(862)
Other adjustments, including the effect of discounting future obligations	89	122
Closed-restaurant reserve, end of the period	$ 1,413	$ 2,028