Changes in Shareholders' Equity (Schedule of Activity in Shareholders' Equity) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Balance			$ 511,290
Net income	$ 15,220	$ 13,409	27,427	$ 36,826
Compensation and benefits paid or payable in shares			1,864
Options exercised			531
Dividends declared			(16,410)
Cumulative translation adjustments			40,794
Pension and postretirement liability adjustments			(929)
Derivative valuation adjustment			89
Balance	564,656		564,656
Common Stock [Member]
Balance			40
Net income
Compensation and benefits paid or payable in shares
Options exercised
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	40		40
Additional Paid-in Capital [Member]
Balance			425,953
Net income
Compensation and benefits paid or payable in shares			1,604
Options exercised			531
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	428,088		428,088
Retained Earnings [Member]
Balance			522,855
Net income			27,225
Compensation and benefits paid or payable in shares
Options exercised
Dividends declared			(16,410)
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	533,670		533,670
Total Other Comprehensive Income [Member]
Balance			(184,189)
Net income
Compensation and benefits paid or payable in shares
Options exercised
Dividends declared
Cumulative translation adjustments			40,775
Pension and postretirement liability adjustments			(929)
Derivative valuation adjustment			89
Balance	(144,254)		(144,254)
Treasury Stock [Member]
Balance			(257,136)
Net income
Compensation and benefits paid or payable in shares			260
Options exercised
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	(256,876)		(256,876)
Noncontrolling Interest [Member]
Balance			3,767
Net income			202
Compensation and benefits paid or payable in shares
Options exercised
Dividends declared
Cumulative translation adjustments			19
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	$ 3,988		$ 3,988