Revenue - Schedule of Revenues Disaggregated by Revenue Source (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2024	Sep. 30, 2023	Sep. 28, 2024	Sep. 30, 2023
Disaggregation Of Revenue [Line Items]
Revenues, net	$ 192,887	$ 214,871	$ 601,508	$ 683,594
Digital Subscription Revenues
Disaggregation Of Revenue [Line Items]
Revenues, net	127,179	140,889	399,364	437,613
Workshops + Digital Subscription Revenues
Disaggregation Of Revenue [Line Items]
Revenues, net	45,015	52,618	138,367	171,473
Clinical Subscription Revenues
Disaggregation Of Revenue [Line Items]
Revenues, net	19,054	9,989	57,529	17,581
Subscription Revenues, net
Disaggregation Of Revenue [Line Items]
Revenues, net	191,248	203,496	595,260	626,667
Other Revenues, net
Disaggregation Of Revenue [Line Items]
Revenues, net	$ 1,639	$ 11,375	$ 6,248	$ 56,927