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 earnings	$ 14,448	$ 34,380	$ 6,954
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	20,674	18,992	16,254
Stock-based compensation	4,184	2,738	3,195
Restructuring loss on pension settlement	0	0	8,280
Pension and other post-retirement plan expense (income)	11,570	(1,599)	(2,451)
Non-recurring environmental expense	0	0	14,541
Deferred income taxes	16,710	10,297	(8,920)
Gain (Loss) on Disposition of Property Plant Equipment	(708)	11,450	2,156
Gain (Loss) on Foreign Currency Derivatives Recorded in Earnings, Net	94	(36)	0
Changes in assets and liabilities, net of acquisitions and divestitures:
Accounts receivable	(5,198)	(7,120)	1,036
Inventories	(5,404)	(2,290)	2,225
Other assets	(1,531)	(289)	4,090
Accounts payable	5,387	537	(5,126)
Accrued Salaries and Benefits	(1,666)	1,876	(3,012)
Accrued expenses	28	451	1,184
Income taxes payable	(4,555)	966	5,264
Other liabilities	(2,918)	(52)	2,502
Pension and other post-retirement plans	(319)	(303)	295
Total adjustments	43,600	12,822	32,197
Net cash provided by operating activities	58,048	47,202	39,151
Cash flows from investing activities:
Capital expenditures	(18,094)	(20,500)	(9,723)
Proceeds from sale of assets	541	12,296	1,878
Payment for acquisitions, net of cash acquired	(19,121)	(73,063)	(1,285)
Net cash used in investing activities	(36,674)	(81,267)	(9,130)
Cash flows from financing activities:
Payments of long-term debt	(1,518,200)	(2,458,400)	(1,343,500)
Proceeds from borrowings of long-term debt	1,505,400	2,456,800	1,359,200
Payments of short-term notes payable	(1,150)	0	(164)
Proceeds from borrowings of short-term notes payable	0	0	164
Purchase of treasury stock	0	0	(18,088)
Dividends paid	(5,260)	(5,234)	(5,291)
Exercise of stock options	0	0	64
Excess tax benefit on stock-based compensation	0	0	313
Payments Related to Tax Withholding for Share-based Compensation	(1,604)	(1,809)	(527)
Net cash used in financing activities	(20,814)	(8,643)	(7,829)
Effect of exchange rate on cash and cash equivalents	(793)	(415)	228
Net (decrease) increase in cash and cash equivalents	(233)	(43,123)	22,420
Cash and cash equivalents at beginning of year	113,805	156,928	134,508
Cash and cash equivalents at end of year	113,572	113,805	156,928
Supplemental cash flow information:
Cash paid for interest	2,130	2,939	2,415
Cash paid for income taxes, net	10,884	10,471	6,779
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Notes Issued	0	1,006	0
Capital Expenditures Incurred but Not yet Paid	$ 5,914	$ 3,214	$ 2,813