Treasury Stock - Additional Information (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Jul. 01, 2016	Jun. 30, 2017	Jul. 01, 2016
Equity Class Of Treasury Stock [Line Items]
Stock repurchase program, authorized amount		$ 10,000,000
Stock repurchase program, period		2 years
Treasury stock purchase, shares	257,000		0	640,000	0
Shares authorized to repurchase, remaining amount	$ 5,500,000			$ 5,500,000
Issued treasury stock, shares	555,000		113,000	613,000	261,000
Remaining shares authorized for repurchase			500,000		500,000
Remaining shares from the trusts recorded as treasury stock	11,276,080	11,077,779		11,276,080
Stock Employee Compensation Trust (SECT) and Omnibus Stock Trust [Member]
Equity Class Of Treasury Stock [Line Items]
Remaining shares from the trusts recorded as treasury stock			2,800,000		2,800,000