Acquisitions - Narrative (Details) $ in Thousands		3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) franchise	Jun. 30, 2018 USD ($) franchise	Dec. 31, 2018 USD ($) store
Business Acquisition [Line Items]
Additional number of businesses acquired | franchise				5	5
Payments to acquire businesses and asset acquisitions				$ (7,612)	$ (14,401)
Franchisee Acquisitions
Business Acquisition [Line Items]
Number of branded stores | store						152
Purchase price	$ 189,826			190,167		$ 189,800
Revenue of acquiree since acquisition date		$ 45,900	$ 4,000	94,800	5,200
Earnings or loss of acquiree since acquisition date		$ (1,100)	$ 600	1,500	800
Acquisition-related costs						$ 1,600
All Acquisitions Excluding SEI Acquisition
Business Acquisition [Line Items]
Payments to acquire businesses and asset acquisitions				$ (7,600)	$ (14,400)