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 (loss)	$ 4,113	$ (141,660)	$ (44,445)
Adjustments to reconcile net income (loss) to cash provided (used) by operating activities:
Deferred income taxes	(1,983)	3,375	(14,582)
Depreciation	12,849	13,917	14,429
Amortization	6,992	9,575	12,245
Asset impairments	0	135,884	80,337
Equity (income) loss and remeasurement (gain)	(6)	1,290	(167)
Loss (gain) on sales and disposals of property, plant, and equipment	18	202	(2,064)
Stock-based compensation	1,696	1,346	1,471
Income tax deficiency (benefit) from stock-based compensation	0	332	(253)
Change in operating assets and liabilities:
Accounts receivable	(9,217)	11,959	31,223
Inventories	(12,648)	10,479	4,331
Other current assets	350	1,380	3,248
Prepaid income tax	13,978	(13,035)	1,134
Other noncurrent assets	959	59	(909)
Dividends from L B Pipe & Coupling Products, LLC	0	0	90
Accounts payable	14,600	(16,005)	(17,204)
Deferred revenue	2,440	984	(2,279)
Accrued payroll and employee benefits	4,260	(2,676)	(5,136)
Other current liabilities	(588)	1,432	(4,189)
Other liabilities	1,559	(433)	(1,108)
Net cash provided by operating activities	39,372	18,405	56,172
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from the sale of property, plant, and equipment	1,462	969	5,339
Capital expenditures on property, plant, and equipment	(6,149)	(7,664)	(14,913)
Acquisitions, net of cash acquired	0	0	(196,001)
Loans and capital contributions to equity method investment	0	(1,235)	0
Net cash used by investing activities	(4,687)	(7,930)	(205,575)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayments of debt	(182,718)	(155,427)	(161,068)
Proceeds from debt	153,118	146,243	301,063
Proceeds from exercise of stock options and stock awards	0	0	68
Financing fees	0	(1,417)	(1,670)
Treasury stock acquisitions	(103)	(342)	(2,701)
Cash dividends on common stock paid to shareholders	0	(1,244)	(1,656)
Income tax (deficiency) benefit from stock-based compensation	0	(332)	253
Net cash (used) provided by financing activities	(29,703)	(12,519)	134,289
Effect of exchange rate changes on cash and cash equivalents	2,333	(905)	(3,598)
Net increase (decrease) in cash and cash equivalents	7,315	(2,949)	(18,712)
Cash and cash equivalents at beginning of period	30,363	33,312	52,024
Cash and cash equivalents at end of period	37,678	30,363	33,312
Supplemental disclosure of cash flow information:
Interest paid	7,589	4,855	3,674
Income taxes (received) paid	(11,189)	3,942	7,835
Capital expenditures funded through financing agreements	$ 0	$ 0	$ 288