Corporate-Owned and Franchisee-Owned Stores - Schedule of Changes in Corporate-owned and Franchisee-owned Stores (Detail) - store	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Number Of Stores [Roll Forward]
Stores operated at beginning of period	1,742	1,518
New stores opened	65	47
Stores acquired, debranded, sold or consolidated	(1)	0
Stores operated at end of period	1,806	1,565
Franchisee-Owned Stores
Number Of Stores [Roll Forward]
Stores operated at beginning of period	1,666	1,456
New stores opened	65	47
Stores acquired, debranded, sold or consolidated	(1)	(6)
Stores operated at end of period	1,730	1,497
Corporate-Owned Stores
Number Of Stores [Roll Forward]
Stores operated at beginning of period	76	62
Stores acquired from franchisees	0	6
Stores operated at end of period	76	68