Fair Value Measurements and Disclosures - Assets and Liabilities Measured at Estimated Fair Value on Recurring Basis Excluding Accrued Interest Components (Parenthetical) (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Jun. 29, 2019	Dec. 29, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents	$ 37,901	$ 2,106
Cash [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total cash equivalents	$ 56,100	$ 108,800