Leases (Supplemental Cash Flow Information) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 27, 2021	Jun. 28, 2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows relating to operating leases	$ 4,684	$ 6,257
Lease liabilities arising from obtaining right-of-use assets:
Operating leases	$ 340	$ 7,503