Segment Reporting - Narrative (Details) $ in Thousands		3 Months Ended		9 Months Ended
	Jul. 17, 2020	Sep. 26, 2020 USD ($)	Sep. 28, 2019 USD ($)	Sep. 26, 2020 USD ($) segment	Sep. 28, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment				2
Corporate level COVID-19 related supplies expense and professional fees		$ 4,700		$ 7,800
Net revenue		485,353	$ 431,902	$ 1,215,064	$ 1,322,568
Walmart
Segment Reporting Information [Line Items]
Management and services agreement, extension (in years)	3 years
Management and services agreement, automatic renewal (in years)	3 years
Period of time prior to end of term for written notice of non-renewal (in months)	7 months
Customer Concentration Risk | Sales revenue | Legacy partner arrangement
Segment Reporting Information [Line Items]
Concentration risk (percent)				8.40%
Customer Concentration Risk | Sales revenue | Walmart and Sam's Club contact lenses distribution arrangements
Segment Reporting Information [Line Items]
Concentration risk (percent)				7.70%
Legacy | Management of operations
Segment Reporting Information [Line Items]
Net revenue		$ 10,100	$ 9,300	$ 23,900	$ 27,500