Supplemental Quarterly Financial Data (Unaudited) - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
	Apr. 02, 2016	Dec. 31, 2015	Oct. 03, 2015	Jul. 04, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jul. 31, 2015
Segment Reporting Information [Line Items]
Goodwill impairment		$ 57,200			$ 0	$ 57,243	$ 0
Intangible asset impairment		32,900			0	32,937	0
Loss on extinguishment of debt			$ 11,900	$ 2,800	0	14,720	$ 0
Debt outstanding		240,661			166,896	240,661
Provision for forward loss reserves		11,925			4,780	11,925
Existing Credit Facilities | Senior Unsecured Notes
Segment Reporting Information [Line Items]
Debt outstanding			200,000					$ 200,000
Call premium incurred on extinguishment of debt			9,800		9,800
Debt issuance costs written off			2,100		$ 2,100
Pittsburgh and Miltec Operations [Member]
Segment Reporting Information [Line Items]
Gain (loss) on disposition of assets	$ 18,800
Structural Systems
Segment Reporting Information [Line Items]
Goodwill impairment		57,200				57,200
Forward loss provision			10,000			10,000
Accrued Liabilities
Segment Reporting Information [Line Items]
Provision for forward loss reserves		7,600	7,600			7,600
Other Noncurrent Liabilities
Segment Reporting Information [Line Items]
Provision for forward loss reserves		$ 2,400	$ 2,400			$ 2,400