Leases - Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 29, 2019	Sep. 29, 2019
Leases
Amortization of right-of-use assets	$ 333	$ 333
Interest on lease liabilities	108	108
Operating lease cost	10,402	31,816
Short-term lease cost	679	2,308
Variable lease cost	2,203	6,945
Total lease costs	13,725	41,510
Sublease income	(2,613)	(7,778)
Total lease costs, net of sublease income	$ 11,112	$ 33,732