Leases (Details) - USD ($) $ in Thousands			3 Months Ended	9 Months Ended
		Sep. 26, 2019	Sep. 30, 2019	Sep. 30, 2019
Other Commitments [Line Items]
Operating Lease, Right-of-Use Asset			$ 51,295	$ 51,295
Operating Lease, Liability			$ 57,196	$ 57,196
Operating Lease, Weighted Average Remaining Lease Term			7 years 6 months	7 years 6 months
Operating Lease, Weighted Average Discount Rate, Percent			3.10%	3.10%
Operating Lease, Payments			$ 2,800
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability			9,200
Operating Lease, Cost	[1]		2,700	$ 8,285
Variable Lease, Cost			487	1,510
Sublease Income			(297)	(918)
Lease, Cost			$ 2,890	$ 8,877
WASHINGTON
Other Commitments [Line Items]
Sale Leaseback Transaction, Date		Sep. 26, 2019
Sale and Leaseback Transaction, Gain (Loss), Net		$ 5,900

[1] Includes short-term lease costs, which are immaterial.