Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows from Operating Activities
Net Income	$ 20,077	$ 25,261	$ (74,879)
Adjustments to Reconcile Net Income (Loss) to Net Cash Provided by Operating Activities
Depreciation and amortization	22,845	22,860	26,846
Gain on divestitures, net	0	(17,604)	0
Goodwill impairment	0	0	57,243
Intangible asset impairment	0	0	32,937
Property and equipment impairment due to restructuring	3,607	0	0
Stock-based compensation expense	4,675	3,007	3,495
Deferred income taxes	(15,411)	3,519	(29,110)
Excess tax benefits from stock-based compensation	0	(248)	(626)
Provision for doubtful accounts	373	112	132
Noncash loss on extinguishment of debt	0	0	4,970
Other	(1,182)	(7,204)	5,628
Changes in Assets and Liabilities:
Accounts receivable	2,720	3,220	4,444
Inventories	(533)	(5,182)	20,985
Production cost of contracts	(267)	(1,536)	330
Other assets	40	2,974	5,884
Accounts payable	(4,015)	15,055	(13,978)
Accrued and other liabilities	2,505	(966)	(20,623)
Net Cash Provided by Operating Activities	35,434	43,268	23,678
Cash Flows from Investing Activities
Purchases of property and equipment	(27,610)	(17,001)	(15,891)
Proceeds from sale of assets	913	16	904
Insurance recoveries related to property and equipment	288	0	1,510
Proceeds from divestitures	0	51,893	0
Payments for purchase of Lightning Diversion Systems, LLC, net of cash acquired	(59,798)	0	0
Net Cash (Used in) Provided by Investing Activities	(86,207)	34,908	(13,477)
Cash Flows from Financing Activities
Borrowings from senior secured revolving credit facility	395,900	71,800	65,000
Repayment of senior secured revolving credit facility	(337,800)	(71,800)	(65,000)
Borrowings from term loan	0	0	275,000
Repayments of senior unsecured notes and term loans	(10,000)	(75,000)	(320,000)
Repayments of other debt	(3)	(23)	(26)
Debt issuance costs	0	0	(4,848)
Excess tax benefits from stock-based compensation	0	248	626
Net cash paid from issuance of common stock under stock plans	(2,606)	(1,423)	(1,126)
Net Cash Provided by (Used in) Financing Activities	45,491	(76,198)	(50,374)
Net (Decrease) Increase in Cash and Cash Equivalents	(5,282)	1,978	(40,173)
Cash and Cash Equivalents at Beginning of Year	7,432	5,454	45,627
Cash and Cash Equivalents at End of Year	$ 2,150	$ 7,432	$ 5,454