Revenue Recognition - Summary of Revenue Disaggregated by Program (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation Of Revenue [Line Items]
Revenue		$ 126,289	$ 95,481	$ 354,444	$ 337,096
Continuing Operations
Disaggregation Of Revenue [Line Items]
Revenue		126,289	95,481	354,444	337,096
Continuing Operations | SilverSneakers
Disaggregation Of Revenue [Line Items]
Revenue		95,772	68,613	266,341	239,377
Continuing Operations | Prime Fitness
Disaggregation Of Revenue [Line Items]
Revenue		24,253	21,687	70,203	73,545
Continuing Operations | WholeHealth Living
Disaggregation Of Revenue [Line Items]
Revenue		6,206	5,040	17,555	14,835
Continuing Operations | Other
Disaggregation Of Revenue [Line Items]
Revenue	[1]	$ 58	$ 141	$ 345	$ 9,339

[1] For the nine months ended September 30, 2020, other revenue in the table above includes $6.8 million from a well-being program with a large employer and $2.2 million of revenue from home-delivered meals