Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities
Net Income	$ 9,035	$ 20,077	$ 25,261
Adjustments to Reconcile Net Income (Loss) to Net Cash Provided by Operating Activities
Depreciation and amortization	25,296	22,845	22,860
Gain on divestitures, net	0	0	(17,604)
Property and equipment impairment due to restructuring	6,207	3,607	0
Stock-based compensation expense	5,040	4,675	3,007
Deferred income taxes	2,042	(15,411)	3,519
Excess tax benefits from stock-based compensation	0	0	(248)
Provision for doubtful accounts	267	373	112
Noncash loss on extinguishment of debt	926	0	0
Other	11,659	(1,182)	(7,204)
Changes in Assets and Liabilities:
Accounts receivable	7,495	2,720	3,220
Contract assets	(86,665)	0	0
Inventories	23,243	(533)	(5,182)
Production cost of contracts	(1,569)	(267)	(1,536)
Other assets	1,881	40	2,974
Accounts payable	18,496	(4,015)	15,055
Contract liabilities	17,145	0	0
Accrued and other liabilities	5,739	2,505	(966)
Net Cash Provided by Operating Activities	46,237	35,434	43,268
Cash Flows from Investing Activities
Purchases of property and equipment	(17,617)	(27,610)	(17,001)
Proceeds from sale of assets	396	913	16
Insurance recoveries related to property and equipment	0	288	0
Proceeds from divestitures	0	0	51,893
Payments for acquisition of Lightning Diversion Systems, LLC, net of cash acquired	0	(59,798)	0
Payments for acquisition of Certified Thermoplastics Co., LLC, net of cash acquired	(30,712)	0	0
Net Cash (Used in) Provided by Investing Activities	(47,933)	(86,207)	34,908
Cash Flows from Financing Activities
Borrowings from senior secured revolving credit facility	296,400	395,900	71,800
Repayment of senior secured revolving credit facility	(354,500)	(337,800)	(71,800)
Borrowings from term loan	240,000	0	0
Repayments of term loan	(167,000)	(10,000)	(75,000)
Repayments of other debt	0	(3)	(23)
Debt issuance costs	(3,541)	0	0
Excess tax benefits from stock-based compensation	0	0	248
Net cash paid from issuance of common stock under stock plans	(1,550)	(2,606)	(1,423)
Net Cash Provided by (Used in) Financing Activities	9,809	45,491	(76,198)
Net (Decrease) Increase in Cash and Cash Equivalents	8,113	(5,282)	1,978
Cash and Cash Equivalents at Beginning of Year	2,150	7,432	5,454
Cash and Cash Equivalents at End of Year	$ 10,263	$ 2,150	$ 7,432