Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net earnings	$ 36,146	$ 46,532	$ 14,448
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	24,619	22,514	20,674
Stock-based compensation	5,015	5,256	4,184
Restructuring and impairment charges	1,704	0	0
Pension and other post-retirement plan expense	1,009	422	11,570
Deferred income taxes	2,413	(1,008)	16,710
(Gain) loss on sale of assets	(63)	0	708
Loss (Gain) on foreign currency hedges, net of cash received	97	(82)	94
Changes in assets and liabilities, net of acquisitions and divestitures:
Accounts receivable	3,784	(9,877)	(5,198)
Inventories	4,371	(7,521)	(5,404)
Other assets	(2,605)	(2,675)	(1,531)
Operating lease assets	(2,578)	0	0
Accounts payable	(4,658)	5,113	5,387
Accrued payroll and benefits	(5,940)	2,349	(1,666)
Accrued expenses and other liabilities	(3,405)	(3,795)	28
Income taxes payable	941	1,564	(4,555)
Operating lease liabilities	2,921	0	0
Other liabilities	921	(258)	2,918
Pension and other post-retirement plans	(287)	(382)	(319)
Total adjustments	28,259	11,620	43,600
Net cash provided by operating activities	64,405	58,152	58,048
Cash flows from investing activities:
Capital expenditures	(21,733)	(28,488)	(18,094)
Proceeds from sale of assets	137	3	541
Payments for acquisitions, net of cash acquired	(73,906)	0	(19,121)
Net cash used in investing activities	(95,502)	(28,485)	(36,674)
Cash flows from financing activities:
Payments of long-term debt	(1,885,800)	(1,060,100)	(1,518,200)
Proceeds from borrowings of long-term debt	1,935,500	1,033,800	1,505,400
Payments of short-term notes payable	0	0	(1,150)
Purchase of treasury stock	(11,746)	(9,440)	0
Dividends paid	(5,238)	(5,285)	(5,260)
Taxes paid on behalf of equity award participants	(2,657)	(1,468)	(1,604)
Net cash provided by (used) in financing activities	30,059	(42,493)	(20,814)
Effect of exchange rate on cash and cash equivalents	346	187	(793)
Net decrease in cash and cash equivalents	(692)	(12,639)	(233)
Cash and cash equivalents at beginning of year	100,933	113,572	113,805
Cash and cash equivalents at end of year	100,241	100,933	113,572
Supplemental cash flow information:
Cash paid for interest	1,961	1,582	2,130
Cash paid for income taxes, net	11,113	9,916	10,884
Noncash Investing and Financing Activities Disclosure [Abstract]
Capital expenditures incurred but not yet paid	$ 4,077	$ 4,312	$ 5,914