Acquisition - Purchase Consideration Allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Aug. 10, 2018	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 199,513		$ 176,981	$ 176,981	$ 176,981
Colorado Acquisition
Business Acquisition [Line Items]
Fixed assets		$ 3,873
Other assets		143
Goodwill		8,476
Liabilities assumed, including deferred revenues		(83)
Net assets acquired		17,239
Long Island Acquisition
Business Acquisition [Line Items]
Fixed assets			4,672
Other assets			275
Goodwill			14,056
Liabilities assumed, including deferred revenues			(310)
Net assets acquired			28,153
Reacquired franchise rights | Colorado Acquisition
Business Acquisition [Line Items]
Intangible assets		4,610
Reacquired franchise rights | Long Island Acquisition
Business Acquisition [Line Items]
Intangible assets			7,640
Customer relationships | Colorado Acquisition
Business Acquisition [Line Items]
Intangible assets		140
Customer relationships | Long Island Acquisition
Business Acquisition [Line Items]
Intangible assets			1,150
Favorable leases, net | Colorado Acquisition
Business Acquisition [Line Items]
Intangible assets		$ 80
Favorable leases, net | Long Island Acquisition
Business Acquisition [Line Items]
Intangible assets			520
Reacquired area development rights | Long Island Acquisition
Business Acquisition [Line Items]
Intangible assets			$ 150