Changes in Shareholders' Equity (Schedule of Activity in Shareholders' Equity) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Balance	$ 511,290
Net income	10,974	$ 13,316
Compensation and benefits paid or payable in shares	989
Options exercised	75
Dividends declared	(5,467)
Cumulative translation adjustments	10,131
Pension and postretirement liability adjustments	(29)
Derivative valuation adjustment	630
Balance	528,593
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
Additional Paid-in Capital [Member]
Balance	425,953
Net income
Compensation and benefits paid or payable in shares	989
Options exercised	75
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	427,017
Retained Earnings [Member]
Balance	522,855
Net income	10,839
Compensation and benefits paid or payable in shares
Options exercised
Dividends declared	(5,467)
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	528,227
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	10,126
Pension and postretirement liability adjustments	(29)
Derivative valuation adjustment	630
Balance	(173,462)
Treasury Stock [Member]
Balance	(257,136)
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	(257,136)
Noncontrolling Interest [Member]
Balance	3,767
Net income	135
Compensation and benefits paid or payable in shares
Options exercised
Dividends declared
Cumulative translation adjustments	5
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	$ 3,907