Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended									12 Months Ended
	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jul. 01, 2017 USD ($)	Apr. 01, 2017 USD ($)	Dec. 31, 2016 USD ($)	Oct. 01, 2016 USD ($)	Jul. 02, 2016 USD ($)	Apr. 02, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 USD ($) Segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Significant Accounting Policies [Line Items]
Number of reportable segments | Segment										2
Non-current deferred income taxes	$ 15,981,000				$ 31,417,000					$ 15,981,000	$ 31,417,000
Net (loss) income	9,484,000	$ 4,655,000	$ 3,823,000	$ 2,115,000	2,836,000	$ 5,014,000	$ 3,861,000	$ 13,550,000		$ 20,077,000	25,261,000	$ (74,879,000)
Cash equivalent maturity period										three months or less
Production cost of contracts	11,204,000				11,340,000					$ 11,204,000	11,340,000
Goodwill impairment										0	0	57,243,000
Goodwill	117,435,000				82,554,000					117,435,000	82,554,000
Carrying value of trade names									$ 0			0
Provision for forward loss reserves	$ 1,226,000				$ 4,780,000					1,226,000	$ 4,780,000
Tax Cuts And Jobs Act of 2017, deferred Income tax benefit										$ 13,000,000
Minimum
Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets (in years)										14 years
Income tax benefit percentage										50.00%
Maximum
Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets (in years)										18 years
Accrued Liabilities
Significant Accounting Policies [Line Items]
Provision for forward loss reserves									7,600,000			7,600,000
Other Long-term Liabilities
Significant Accounting Policies [Line Items]
Provision for forward loss reserves									2,400,000			2,400,000
Structural Systems
Significant Accounting Policies [Line Items]
Goodwill impairment												57,200,000
Goodwill									0			0
Forward loss provision												$ 10,000,000
Trade name
Significant Accounting Policies [Line Items]
Impairment of trade names									$ 32,900,000