Adoption of ASC 842, "Leases" (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2019	Dec. 31, 2018	Dec. 30, 2018
Lessee, Lease, Description [Line Items]
Election of package of practical expedients	true
Election of hindsight practical expedient	false
Assets
Prepaid expenses	$ 18,450	$ 25,707	$ 30,376
Operating lease right-of-use assets	144,881	161,027
Current liabilities:
Current operating lease liabilities	23,701	25,348
Long-term liabilities:
Long-term operating lease liabilities	121,320	137,511
Other long-term liabilities	$ 83,664	72,823	79,324
Total Adjustments
Assets
Prepaid expenses			$ 441
Accounting Standards Update 2016-02 | Total Adjustments
Assets
Prepaid expenses		(4,669)
Operating lease right-of-use assets		161,027
Current liabilities:
Current operating lease liabilities		25,348
Long-term liabilities:
Long-term operating lease liabilities		137,511
Other long-term liabilities		$ (6,501)