Summary of Significant Accounting Policies - Life Insurance Policies (Details) $ in Thousands	3 Months Ended
	Mar. 27, 2020 USD ($) Individual	Dec. 31, 2019 USD ($)
Supplementary Information For Corporate Owned Life Insurance [Line Items]
Number of former employees covered under insurance policies | Individual	18
Average age of former employees covered under insurance policies	76 years
Gross cash surrender values of life insurance	$ 29,900	$ 29,700
Loans on cash surrender value	27,600	27,200
Net cash surrender values of life insurance	2,931	3,133
Gross death benefit of life insurance contracts	37,700	37,700
Life insurance proceeds to be received upon the death of participants	9,800
Life insurance gain to be recognized upon death of participants	7,500
Non-Qualified Defined Benefit Executive Supplemental Benefit Plan [Member]
Supplementary Information For Corporate Owned Life Insurance [Line Items]
Net cash surrender values of life insurance	$ 2,300	$ 2,500