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Segments - Additional Information (Detail)	3 Months Ended		9 Months Ended
Segments - Additional Information (Detail)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) segment	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments \| segment			3
Number of operating segments \| segment			0
Revenue	$ 166,815,000	$ 136,656,000	$ 497,292,000	$ 398,538,000
Assets	1,420,232,000		1,420,232,000		$ 1,353,416,000
Franchise revenue
Segment Reporting Information [Line Items]
Revenue	66,709,000	54,822,000	204,283,000	167,584,000
Franchise revenue \| Placement Services
Segment Reporting Information [Line Items]
Revenue	4,277,000	2,518,000	12,112,000	7,694,000
Corporate-owned Stores
Segment Reporting Information [Line Items]
Revenue	40,742,000	$ 35,406,000	118,481,000	$ 102,365,000
Corporate-owned Stores \| Canada
Segment Reporting Information [Line Items]
Long-lived assets	1,204,000		1,204,000		1,892,000
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenue			0
Operating Segments \| Franchise revenue
Segment Reporting Information [Line Items]
Assets	189,192,000		189,192,000		185,899,000
Operating Segments \| Corporate-owned Stores
Segment Reporting Information [Line Items]
Assets	390,101,000		390,101,000		243,221,000
Unallocated
Segment Reporting Information [Line Items]
Assets	$ 645,917,000		$ 645,917,000		713,834,000
Reclassification \| Operating Segments \| Franchise revenue
Segment Reporting Information [Line Items]
Assets					(133,523,000)
Reclassification \| Unallocated
Segment Reporting Information [Line Items]
Assets					$ 133,523,000