Business Acquisition (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
Business Acquisition [Line Items]
Maximum revolving secured credit line		$ 20,000,000
Goodwill	$ 60,470,000	62,030,000	$ 61,888,000	$ 2,520,000
Octane Fitness
Business Acquisition [Line Items]
Purchase price	115,000,000.0
Goodwill		59,705,000
JPMorgan Chase Bank, N.A. | Term Loan | Line of Credit
Business Acquisition [Line Items]
Maximum revolving secured credit line		$ 80,000,000
JPMorgan Chase Bank, N.A. | Term Loan | Line of Credit | Octane Fitness
Business Acquisition [Line Items]
Maximum revolving secured credit line	$ 80,000,000.0