Changes in Shareholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Balance			$ 513,568
Net income	$ 9,680	$ 11,774	19,799	$ 33,644
Compensation and benefits paid or payable in shares			1,118
Options exercised			2,401
Shares issued to Directors			166
Dividends declared			(15,991)
Cumulative translation adjustment			(44,315)
Pension and postretirement liability adjustments			2,449
Derivative valuation adjustment			(1,435)
Balance	477,760		477,760
Common Stock [Member]
Balance			$ 40
Net income
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors
Dividends declared
Cumulative translation adjustment
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	40		$ 40
Additional Paid-in Capital [Member]
Balance			$ 418,972
Net income
Compensation and benefits paid or payable in shares			$ 1,118
Options exercised			2,401
Shares issued to Directors			$ 76
Dividends declared
Cumulative translation adjustment
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	422,567		$ 422,567
Retained Earnings [Member]
Balance			456,105
Net income			$ 19,699
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors
Dividends declared			$ (15,991)
Cumulative translation adjustment
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	459,813		$ 459,813
Accumulated Items of Other Comprehensive Income [Member]
Balance			$ (107,767)
Net income
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors
Dividends declared
Cumulative translation adjustment			$ (44,316)
Pension and postretirement liability adjustments			2,449
Derivative valuation adjustment			(1,435)
Balance	(151,069)		(151,069)
Treasury Stock [Member]
Balance			$ (257,481)
Net income
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors			$ 90
Dividends declared
Cumulative translation adjustment
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	(257,391)		$ (257,391)
Noncontrolling Interest [Member]
Balance			3,699
Net income			$ 100
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors
Dividends declared
Cumulative translation adjustment			$ 1
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	$ 3,800		$ 3,800