Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 115,496	$ 110,173	$ 350,798	$ 329,613
Membership dues
Disaggregation of Revenue [Line Items]
Revenues	89,687	84,162	268,378	251,992
Initiation and processing fees
Disaggregation of Revenue [Line Items]
Revenues	122	337	954	1,006
Membership revenue
Disaggregation of Revenue [Line Items]
Revenues	89,809	84,499	269,332	252,998
Personal training revenue
Disaggregation of Revenue [Line Items]
Revenues	18,222	18,019	58,079	55,451
Other ancillary club revenue
Disaggregation of Revenue [Line Items]
Revenues	5,833	6,191	18,620	16,982
Ancillary club revenue
Disaggregation of Revenue [Line Items]
Revenues	24,055	24,210	76,699	72,433
Fees and other revenue
Disaggregation of Revenue [Line Items]
Revenues	$ 1,632	$ 1,464	$ 4,767	$ 4,182