Changes in Shareholders' Equity (Schedule of Activity in Shareholders' Equity) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Balance			$ 502,553
Net income	$ 13,409	$ 9,680	36,826	$ 19,799
Compensation and benefits paid or payable in shares			1,447
Options exercised			570
Shares issued to Directors'			435
Dividends declared			(16,370)
Cumulative translation adjustments			2,215
Pension and postretirement liability adjustments			702
Derivative valuation adjustment			(3,255)
Balance	525,123		525,123
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 adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	40		40
Additional Paid-in Capital [Member]
Balance			423,108
Net income
Compensation and benefits paid or payable in shares			1,447
Options exercised			570
Shares issued to Directors'			190
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	425,315		425,315
Retained Earnings [Member]
Balance			491,950
Net income			36,937
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors'
Dividends declared			(16,370)
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	512,517		512,517
Accumulated Other Comprehensive Income (Loss) [Member]
Balance			(158,844)
Net income
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors'
Dividends declared
Cumulative translation adjustments			2,216
Pension and postretirement liability adjustments			702
Derivative valuation adjustment			(3,255)
Balance	(159,181)		(159,181)
Treasury Stock [Member]
Balance			(257,391)
Net income
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors'			245
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	(257,146)		(257,146)
Noncontrolling Interest [Member]
Balance			3,690
Net income			(111)
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors'
Dividends declared
Cumulative translation adjustments			(1)
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	$ 3,578		$ 3,578