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), Including Portion Attributable to Noncontrolling Interest	$ 22,300	$ 63,039	$ 52,706
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	12,598	12,557	12,395
Amortization	7,368	7,009	6,811
Equity in undistributed earnings of associated companies, net of dividends	(2,895)	(1,969)	578
Deferred income taxes	(3,754)	(5,488)	2,401
Uncertain tax positions (non-deferred portion)	(817)	(3,206)	(1,122)
Non-current income taxes payable	15,825	0	0
Deferred compensation and other, net	1,074	(424)	14
Share-based compensation	4,190	6,349	5,919
Restructuring and related activities	0	(439)	6,790
Loss (gain) on disposal of property, plant and equipment and other assets	79	(18)	(12)
Insurance settlement realized	(762)	(1,023)	(760)
Combination related expenses, net of payements	4,952	503	0
Pension and other postretirement benefits contributions	(123)	(3,420)
Pension And Other Postretirement Benefit Expense			2,591
(Decrease) increase in cash from changes in current assets and current liabilities, net of acquisitions:
Accounts receivable	(1,941)	(11,705)	(188)
Inventories	(6,135)	(1,870)	1,292
Prepaid expenses and other current assets	(2,932)	(703)	(721)
Accounts payable and accrued liabilities	12,381	14,063	(9,040)
Restructuring liabilities	(675)	(5,252)	(490)
Estimated taxes on income	(3,479)	(5,226)	(930)
Net cash provided by operating activities	64,762	73,753	73,432
Cash flows from investing activities
Investments in property, plant and equipment	(10,872)	(9,954)	(11,033)
Payments related to acquisitions, net of cash acquired	(5,363)	(15,024)	(24,058)
Proceeds from disposition of assets	1,577	186	135
Insurance settlement interest earned	50	32	35
Change in restricted cash, net	712	991	725
Net cash used in investing activities	(13,896)	(23,769)	(34,196)
Cash flows from financing activities
Proceeds from long-term debt	0	0	6,163
Repayment of long-term debt	(2,853)	(14,513)	(477)
Dividends paid	(18,613)	(17,625)	(16,513)
Stock options exercised, other	(1,956)	(811)	1,048
Payments for repurchase of common stock	0	(5,859)	(7,276)
Excess tax benefit from stock option exercises	0	678	384
Purchase of noncontrolling interest in affiliates, net	(31,787)	0	0
Payment of acquisition-related liabilities		0	(226)
Distributions to noncontrolling affiliate shareholders	0	0	0
Net cash used in financing activities	(55,209)	(38,130)	(16,897)
Effect of exchange rate changes on cash	5,404	(4,089)	(6,017)
Net increase (decrease) in cash and cash equivalents	1,061	7,765	16,322
Cash and cash equivalents at beginning of period	88,818	81,053	64,731
Cash and cash equivalents at end of period	89,879	88,818	81,053
Supplemental Cash Flow Information [Abstract]
Income Taxes Paid	21,544	25,043	20,996
Interest Paid	2,767	2,481	2,223
Other Noncash Investing And Financing Items [Abstract]
Change in accrued purchases of property, plant and equipment, net	$ 240	$ 363	$ 209