Shareholders' Equity (Schedule of Activity in Shareholders' Equity) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Balance	$ 547,779
Balance, shares	31,800,000	31,400,000
Net income	41,749	17,658	30,977
Cumulative translation adjustments	(55,102)	7,521	18,287
Settlement of certain pension plan liabilities	5,167
Balance	513,568	547,779
Balance, shares	31,900,000	31,800,000	31,400,000
Common Class B [Member]
Balance, shares	3,235,048	3,236,048
Common Stock [Member] | Common Class A [Member]
Balance	37	37	37
Balance, shares	36,996,000	36,642,000	36,541,000
Compensation and benefits paid or payable in shares
Compensation and benefits paid or payable in shares, shares	47,000	75,000	34,000
Conversion of Class B shares to Class A shares
Conversion of Class B shares to Class A shares, shares	1,000
Initial equity related to Noncontrolling interest in ASC
Changes in equity related to Noncontrolling interest in ASC
Options exercised
Options exercised, shares	41,000	279,000	67,000
Shares issued to Directors'
Shares issued to Directors', shares
Net income
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	37	37	37
Balance, shares	37,085,000	36,996,000	36,642,000
Common Stock [Member] | Common Class B [Member]
Balance	3	3	3
Balance, shares	3,236,000	3,236,000	3,236,000
Compensation and benefits paid or payable in shares
Compensation and benefits paid or payable in shares, shares
Conversion of Class B shares to Class A shares
Conversion of Class B shares to Class A shares, shares	(1,000)
Initial equity related to Noncontrolling interest in ASC
Changes in equity related to Noncontrolling interest in ASC
Options exercised
Options exercised, shares
Shares issued to Directors'
Shares issued to Directors', shares
Net income
Dividends declared
Cumulative translation adjustments
Settlement of certain pension plan liabilities
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	3	3	3
Balance, shares	3,235,000	3,236,000	3,236,000
Additional Paid-in Capital [Member]
Balance	416,728	395,381	391,495
Compensation and benefits paid or payable in shares	1,234	(902)	2,573
Conversion of Class B shares to Class A shares
Initial equity related to Noncontrolling interest in ASC		15,535
Changes in equity related to Noncontrolling interest in ASC	(24)
Options exercised	974	6,670	1,352
Shares issued to Directors'	60	44	(39)
Net income
Dividends declared
Cumulative translation adjustments
Settlement of certain pension plan liabilities
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	418,972	416,728	395,381
Retained Earnings [Member]
Balance	434,598	435,775	422,044
Compensation and benefits paid or payable in shares
Conversion of Class B shares to Class A shares
Initial equity related to Noncontrolling interest in ASC
Changes in equity related to Noncontrolling interest in ASC
Options exercised
Shares issued to Directors'
Net income	41,569	17,517	30,977
Dividends declared	(20,062)	(18,694)	(17,246)
Cumulative translation adjustments
Settlement of certain pension plan liabilities
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	456,105	434,598	435,775
Accumulated Other Comprehensive Income (Loss) [Member]
Balance	(49,498)	(80,021)	(139,809)
Compensation and benefits paid or payable in shares
Conversion of Class B shares to Class A shares
Initial equity related to Noncontrolling interest in ASC
Changes in equity related to Noncontrolling interest in ASC
Options exercised
Shares issued to Directors'
Net income
Dividends declared
Cumulative translation adjustments	(55,102)	7,521	11,452
Settlement of certain pension plan liabilities			79,204
Pension and postretirement liability adjustments	(3,283)	21,101	(30,584)
Derivative valuation adjustment	116	1,901	(284)
Balance	(107,767)	(49,498)	(80,021)
Treasury Stock [Member]
Balance	(257,571)	(257,664)	(257,920)
Balance, shares	(8,464,000)	(8,468,000)	(8,480,000)
Compensation and benefits paid or payable in shares
Compensation and benefits paid or payable in shares, shares
Conversion of Class B shares to Class A shares
Conversion of Class B shares to Class A shares, shares
Initial equity related to Noncontrolling interest in ASC
Changes in equity related to Noncontrolling interest in ASC
Options exercised
Options exercised, shares
Shares issued to Directors'	90	93	256
Shares issued to Directors', shares	5,000	4,000	12,000
Net income
Dividends declared
Cumulative translation adjustments
Settlement of certain pension plan liabilities
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	(257,481)	(257,571)	(257,664)
Balance, shares	(8,459,000)	(8,464,000)	(8,468,000)
Noncontrolling Interest [Member]
Balance	3,482
Compensation and benefits paid or payable in shares
Conversion of Class B shares to Class A shares
Initial equity related to Noncontrolling interest in ASC		3,341
Changes in equity related to Noncontrolling interest in ASC	38
Options exercised
Shares issued to Directors'
Net income	180	141
Dividends declared
Cumulative translation adjustments	(1)
Settlement of certain pension plan liabilities
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	$ 3,699	$ 3,482