Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 25,823	$ 47,974	$ (30,586)
Adjustments to reconcile net income (loss) to cash provided (used) by operating activities:
Deferred income taxes	(4,317)	(30,392)	(1,598)
Depreciation	7,850	7,944	8,066
Amortization	5,729	6,445	6,966
Concrete Tie Settlement expense (Note 18)	0	0	43,400
Equity (income) loss in nonconsolidated investments	(20)	(17)	7
Loss (gain) on sales and disposals of property, plant, and equipment	47	(103)	511
Loss on derivative	273	0	0
Stock-based compensation	1,136	3,155	3,836
Pension settlement	0	2,210	0
Change in operating assets and liabilities:
Accounts receivable	15,722	3,368	(9,654)
Inventories	3,279	6,500	(23,502)
Other current assets	583	1,349	25
Prepaid income tax	(9,108)	437	(249)
Other noncurrent assets	(2,870)	(402)	1,319
Accounts payable	(8,947)	(13,024)	24,726
Deferred revenue	(1,315)	1,782	(3,491)
Accrued payroll and employee benefits	(4,085)	1,130	1,637
Accrued settlement	(8,000)	(10,000)	0
Other current liabilities	(4,074)	(998)	5,893
Other liabilities	2,843	(1,116)	(770)
Net cash provided by continuing operating activities	20,549	26,242	26,536
Net cash (used in) provided by discontinued operating activities	(3,631)	3,055	(572)
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from the sale of property, plant, and equipment	16	930	2,309
Capital expenditures on property, plant, and equipment	(9,179)	(6,026)	(3,658)
Acquisition	(1,156)	0	0
Capital expenditures on property, plant, and equipment	0	0	3,875
Repayment of revolving line of credit from equity method investment	0	0	1,235
Net cash (used in) provided by continuing investing activities	(10,319)	(5,096)	3,761
Net cash provided by (used in) discontinued investing activities	2,278	(2,584)	(1,513)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayments of debt	(172,892)	(210,286)	(195,202)
Proceeds from debt	159,778	193,534	140,181
Debt issuance costs	(498)	(836)	0
Treasury stock acquisitions	(1,665)	(621)	(316)
Net cash used in continuing financing activities	(15,277)	(18,209)	(55,337)
Net cash (used in) provided by discontinued financing activities	(19)	(37)	37
Effect of exchange rate changes on cash and cash equivalents	(195)	525	(308)
Net (decrease) increase in cash and cash equivalents	(6,614)	3,896	(27,396)
Cash and cash equivalents at beginning of period	14,178	10,282	37,678
Cash and cash equivalents at end of period	7,564	14,178	10,282
Supplemental disclosure of cash flow information:
Interest paid	3,266	4,587	5,577
Income taxes paid	$ 2,625	$ 6,513	$ 4,512