Summary of Significant Accounting Policies - Life Insurance Policies (Details)	9 Months Ended
	Sep. 29, 2017 USD ($) Individual	Dec. 31, 2016 USD ($)
Accounting Policies [Abstract]
Number of former employees covered under insurance policies | Individual	20
Average age of former employees covered under insurance policies	74 years
Gross cash surrender values of life insurance	$ 30,600,000	$ 30,100,000
Loans on cash surrender value	0
Gross death benefit of life insurance contracts	42,100,000	$ 41,100,000
Life insurance proceeds to be received upon the death of participants	41,500,000
Life insurance gain to be recognized upon death of participants	$ 10,900,000