Corporate-Owned and Franchisee-Owned Stores - Schedule of Changes in Corporate-owned and Franchisee-owned Stores (Detail) - store	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Number Of Stores [Roll Forward]
Stores operated at beginning of period	1,806	1,565	1,742	1,518
New stores opened	53	44	118	91
Stores acquired, debranded, sold or consolidated	0	(1)	(1)	(1)
Stores operated at end of period	1,859	1,608	1,859	1,608
Franchisee-Owned Stores
Number Of Stores [Roll Forward]
Stores operated at beginning of period	1,730	1,497	1,666	1,456
New stores opened	53	44	118	91
Stores acquired, debranded, sold or consolidated	(4)	(1)	(5)	(7)
Stores operated at end of period	1,779	1,540	1,779	1,540
Corporate-Owned Stores
Number Of Stores [Roll Forward]
Stores operated at beginning of period	76	68	76	62
Stores acquired from franchisees	4	0	4	6
Stores operated at end of period	80	68	80	68