Revenue from Contracts with Customers - Net Change in Estimate (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2020 USD ($) positions	Jun. 30, 2019 USD ($) positions	Jun. 28, 2020 USD ($) positions	Jun. 30, 2019 USD ($) positions
Revenue from Contract with Customer [Abstract]
Decrease in revenue from net changes in transaction prices	$ (308)	$ 0	$ (308)	$ (3,301)
Increase (decrease) in revenue from net changes in input cost estimates	1,082	0	(51)	2,410
Net decrease in revenue from net changes in estimates	$ 774	$ 0	$ (359)	$ (891)
Number of projects | positions	1	0	2	1
Net change in estimate as a percentage of aggregate revenue for associated projects	11.50%	0.00%	(0.30%)	(11.30%)