Contract Assets, Contract Costs and Contract Liabilities (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 28, 2019	Jun. 29, 2018	Jun. 28, 2019	Jun. 29, 2018	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Contract assets	$ 118,774,000		$ 118,774,000		$ 99,261,000
Contract assets, change			$ 19,513,000
Contract assets, change (as percent)			19.70%
Contract costs, current portion	5,114,000		$ 5,114,000		5,993,000
Capitalized costs, current portion, change			$ (879,000)
Capitalized costs, current portion, change (as percent)			(14.70%)
Contract costs, noncurrent portion	9,187,000		$ 9,187,000		10,666,000
Capitalized costs, noncurrent portion, change			$ (1,479,000)
Capitalized costs, noncurrent portion, change (as percent)			(13.90%)
Contract liabilities, current portion	30,707,000		$ 30,707,000		28,865,000
Contract liabilities, current portion, change			$ 1,842,000
Contract liabilities, current portion, change (as percent)			6.40%
Contract liabilities, noncurrent portion	72,081,000		$ 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	$ 0	$ 0
Capitalized contract cost, amortization	2,000,000.0	1,000,000.0	3,000,000.0	1,700,000
Revenue recognized related to contract liabilities	6,000,000.0	$ 1,400,000	14,000,000.0	$ 6,400,000
Contract changes, negotiated settlements and claims for unanticipated contract costs
Disaggregation of Revenue [Line Items]
Contract assets	3,574,000		3,574,000		2,909,000
Costs to Fulfill [Member]
Disaggregation of Revenue [Line Items]
Capitalized Contract Cost, Net	6,300,000		6,300,000		8,900,000
Costs to Obtain [Member]
Disaggregation of Revenue [Line Items]
Capitalized Contract Cost, Net	$ 8,000,000.0		$ 8,000,000.0		$ 7,800,000