Credit Agreement (Details) - USD ($) $ in Thousands	6 Months Ended
	Jul. 01, 2017	Mar. 31, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Current borrowing capacity	$ 153,150	$ 150,000
Line of Credit Facility, Maximum Borrowing Capacity	$ 200,000
Line of Credit Facility, Expiration Date	Feb. 24, 2021
Borrowings under revolving credit facility	$ 13,950		$ 0
Letters of Credit Outstanding, Amount	3,150
Line of Credit Facility, Remaining Borrowing Capacity	$ 136,000
Weighted-Average Interest Rate at Period End	3.30%