Revenue Recognition - Contract Balances (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Apr. 01, 2018	Dec. 30, 2018
Revenue, Major Customer [Line Items]
Revenue recognized related to deferred revenue and customer loyalty program	$ 7,400,000	$ 4,100,000
Contract liabilities	40,373,000		$ 41,291,000
Change	(918,000)
Contract assets	6,600,000		6,600,000
Amortization expense related to contract assets	800,000
Deferred revenue.
Revenue, Major Customer [Line Items]
Contract liabilities	21,078,000		23,272,000
Change	(2,194,000)
Customer loyalty program
Revenue, Major Customer [Line Items]
Contract liabilities	19,295,000		$ 18,019,000
Change	$ 1,276,000