Intangible Assets and Goodwill - Components of Company's Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Net Balance	$ 107,032		$ 107,032		$ 119,349
Amortization expense	5,300	$ 4,100	14,400	$ 15,100
Increase in depreciation and amortization expense	400		400
Franchise agreements
Finite Lived Intangible Assets [Line Items]
Initial Cost	180,867		180,867		181,567
Accumulated Amortization	(73,835)		(73,835)		(62,218)
Net Balance	107,032		$ 107,032		119,349
Franchise agreements | Weighted Average
Finite Lived Intangible Assets [Line Items]
Useful life of intangible assets			12 years 6 months
Other intangible assets
Finite Lived Intangible Assets [Line Items]
Initial Cost	33,214		$ 33,214		17,801
Accumulated Amortization	(11,303)		(11,303)		(9,325)
Net Balance	21,911		$ 21,911		8,476
Other intangible assets | Weighted Average
Finite Lived Intangible Assets [Line Items]
Useful life of intangible assets			6 years
Software
Finite Lived Intangible Assets [Line Items]
Initial Cost	22,916		$ 22,916		13,762
Accumulated Amortization	(9,630)		(9,630)		(8,111)
Net Balance	13,286		$ 13,286		5,651
Software | Weighted Average
Finite Lived Intangible Assets [Line Items]
Useful life of intangible assets			4 years 7 months 6 days
Trademarks
Finite Lived Intangible Assets [Line Items]
Initial Cost	1,859		$ 1,859		1,539
Accumulated Amortization	(788)		(788)		(902)
Net Balance	1,071		$ 1,071		637
Trademarks | Weighted Average
Finite Lived Intangible Assets [Line Items]
Useful life of intangible assets			9 years 3 months 18 days
Software Development
Finite Lived Intangible Assets [Line Items]
Capitalized software development costs	2,400		$ 2,400		600
Non-compete agreements
Finite Lived Intangible Assets [Line Items]
Initial Cost	3,700		3,700		2,500
Accumulated Amortization	(733)		(733)		(312)
Net Balance	2,967		$ 2,967		$ 2,188
Non-compete agreements | Weighted Average
Finite Lived Intangible Assets [Line Items]
Useful life of intangible assets			7 years 8 months 12 days
Training materials
Finite Lived Intangible Assets [Line Items]
Initial Cost	2,350		$ 2,350
Net Balance	2,350		$ 2,350
Training materials | Weighted Average
Finite Lived Intangible Assets [Line Items]
Useful life of intangible assets			5 years
Other
Finite Lived Intangible Assets [Line Items]
Initial Cost	2,389		$ 2,389
Accumulated Amortization	(152)		(152)
Net Balance	$ 2,237		$ 2,237
Other | Weighted Average
Finite Lived Intangible Assets [Line Items]
Useful life of intangible assets			11 years 10 months 24 days