Revenue Recognition - Summary of Revenue Disaggregated by Program (Parenthetical) (Details) - USD ($) $ in Thousands	3 Months Ended											12 Months Ended
	Dec. 31, 2020	[1]	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	[2]	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	[3]	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation Of Revenue [Line Items]
Revenues	$ 100,617		$ 95,481	$ 81,923	$ 159,692	$ 159,080		$ 159,979	$ 157,480	$ 156,527		$ 437,714	$ 633,066	$ 606,299
Other
Disaggregation Of Revenue [Line Items]
Revenues												6,800
Well-Being Program
Disaggregation Of Revenue [Line Items]
Revenues												$ 2,200

[1] Income from continuing operations for the fourth quarter of 2020 includes strategic project costs, CEO transition costs, and acquisition and integration costs of $2.3 million, $1.0 million, and $0.6 million, respectively, each of which were primarily recorded to selling, general, and administrative expenses.

[2] Income from continuing operations for the fourth quarter of 2019 includes acquisition, integration, and project costs totaling $4.3 million, which were primarily recorded to selling, general, and administrative expenses.

[3] The impact of potentially dilutive securities for the three months ended March 31, 2019 was not considered because the impact on continuing operations would be anti-dilutive.