Debt - Effect of Derivatives on Financial Statements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018
Debt and Credit Arrangements
Weighted average interest rates on debt, including the impact of interest rate swap agreements	4.30%	3.60%	4.40%	3.60%
Interest paid, including payments made or received under the swaps	$ 4,400	$ 5,800	$ 11,100	$ 10,700
Interest rate swap
Debt and Credit Arrangements
Portion of derivative asset that would be reclassified into earnings			6,200
Interest income | Interest rate swap
Debt and Credit Arrangements
Amount of Gain or (Loss) Recognized in AOCI/AOCL on Derivative	(5,167)
Amount of Gain or (Loss) Reclassified from AOCI/AOCL into Income	231
Total Net interest expense on Consolidated Statements of Operations	$ (4,272)
Interest expense | Interest rate swap
Debt and Credit Arrangements
Amount of Gain or (Loss) Recognized in AOCI/AOCL on Derivative		2,207	(8,204)	7,380
Amount of Gain or (Loss) Reclassified from AOCI/AOCL into Income		(89)	688	(197)
Total Net interest expense on Consolidated Statements of Operations		$ (5,797)	(10,548)	$ (10,872)
Portion of derivative asset that would be reclassified into earnings			$ 1,500
Estimate of period of time over which portion of derivative liability would be reclassified into earnings			12 months