Summary of Significant Accounting Policies - Transaction Price (Details) $ in Thousands	Jun. 30, 2020 USD ($)
Annual Dues And Franchise Sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 41,121
Annual dues
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	16,388
Franchise sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	24,733
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01 | Annual Dues And Franchise Sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 15,889
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01 | Annual dues
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 12,258
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01 | Franchise sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 3,631
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Annual Dues And Franchise Sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 10,404
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Annual dues
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 4,130
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Franchise sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 6,274
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Annual Dues And Franchise Sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 4,894
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Annual dues
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Franchise sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 4,894
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Annual Dues And Franchise Sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 3,464
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Annual dues
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Franchise sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 3,464
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | Annual Dues And Franchise Sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 2,178
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | Annual dues
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | Franchise sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 2,178
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 | Annual Dues And Franchise Sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 1,109
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 | Annual dues
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 | Franchise sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 1,109
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01 | Annual Dues And Franchise Sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 3,183
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01 | Annual dues
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01 | Franchise sales
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation revenue	$ 3,183
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period 1