Revenue Recognition - Summary of Revenue Disaggregated by Program (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation Of Revenue [Line Items]
Revenue	[1]	$ 262,598	$ 340,377	$ 600,253	$ 554,471
Other
Disaggregation Of Revenue [Line Items]
Revenue		6,800		6,800
Healthcare
Disaggregation Of Revenue [Line Items]
Revenue		81,923	157,481	241,615	314,008
Healthcare | SilverSneakers
Disaggregation Of Revenue [Line Items]
Revenue		49,157	122,899	170,764	245,922
Healthcare | Prime Fitness
Disaggregation Of Revenue [Line Items]
Revenue		19,047	29,751	51,858	58,494
Healthcare | WholeHealth Living
Disaggregation Of Revenue [Line Items]
Revenue		4,747	4,467	9,796	9,041
Healthcare | Other
Disaggregation Of Revenue [Line Items]
Revenue	[2]	$ 8,972	$ 364	$ 9,197	$ 551

[1] The figure for total segments equals the consolidated figure for such item.

[2] For the three and six months ended June 30, 2020, other revenue in the table above includes $6.8 million from a well-being program with a large employer as well as $2.1 million of Wisely Well revenue.