Contract Assets, Contract Costs and Contract Liabilities (Details) - USD ($)	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Contract assets	$ 121,621,000		$ 108,861,000
Contract assets, change	$ 12,760,000
Contract assets, change (as percent)	11.70%
Contract costs, current portion	$ 6,158,000		5,993,000
Capitalized costs, current portion, change	$ 165,000
Capitalized costs, current portion, change (as percent)	2.80%
Contract costs, noncurrent portion	$ 9,503,000		10,666,000
Capitalized costs, noncurrent portion, change	$ (1,163,000)
Capitalized costs, noncurrent portion, change (as percent)	(10.90%)
Contract liabilities, current portion	$ 34,283,000		28,865,000
Contract liabilities, current portion, change	$ 5,418,000
Contract liabilities, current portion, change (as percent)	18.80%
Contract liabilities, noncurrent portion	$ 72,081,000		78,562,000
Contract liabilities, noncurrent portion, change	$ (6,481,000)
Contract liabilities, noncurrent portion, change (as percent)	(8.20%)
Impairment loss	$ 0	$ 0
Capitalized contract cost, amortization	1,000,000	700,000
Revenue recognized related to contract liabilities	8,000,000	$ 5,000,000
Contract changes, negotiated settlements and claims for unanticipated contract costs
Disaggregation of Revenue [Line Items]
Contract assets	3,631,000		2,909,000
Costs to Fulfill [Member]
Disaggregation of Revenue [Line Items]
Capitalized Contract Cost, Net	8,500,000		8,900,000
Costs to Obtain [Member]
Disaggregation of Revenue [Line Items]
Capitalized Contract Cost, Net	$ 7,200,000		$ 7,800,000