Shareholders' Equity (Schedule of Activity in Shareholders' Equity) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2009	Sep. 30, 2009	Jun. 30, 2009	Mar. 31, 2009	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Balance				$ 426,259									$ 426,259
Balance, shares				31,200,000				30,900,000					31,200,000	30,900,000
Options exercised, shares													41,450	7,230	1,520
Net income/(loss)	(7,200)	16,700	8,800	16,700	20,500	3,600	7,900	5,600	3,700	(5,100)	(12,700)	(19,400)	34,938	37,636	(33,458)
Dividends declared													(15,942)	(14,923)	(14,704)
Balance	415,850				426,259								415,850	426,259
Balance, shares	31,300,000				31,200,000				30,900,000				31,300,000	31,200,000	30,900,000
Common Class A [Member]
Balance				36				36				35	36	36	35
Balance, shares				36,442,000				36,149,000				35,245,000	36,442,000	36,149,000	35,245,000
Compensation and benefits paid or payable in shares													1		1
Compensation and benefits paid or payable in shares, shares													14,000	263,000	880,000
Options exercised
Options exercised, shares													42,000	7,000	2,000
Shares issued to Directors
Shares issued to Directors, shares
Long-term incentive plan
Long-term incentive plan, shares													43,000	23,000	22,000
Stock option expense
Convertible notes purchased
Settlement of equity-related tax issues
Net income/(loss)
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	37				36				36				37	36	36
Balance, shares	36,541,000				36,442,000				36,149,000				36,541,000	36,442,000	36,149,000
Common Class B [Member]
Balance				3				3				3	3	3	3
Balance, shares				3,236,000				3,236,000				3,236,000	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
Options exercised
Options exercised, shares
Shares issued to Directors
Shares issued to Directors, shares
Long-term incentive plan
Long-term incentive plan, shares
Stock option expense
Convertible notes purchased
Settlement of equity-related tax issues
Net income/(loss)
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	3				3				3				3	3	3
Balance, shares	3,236,000				3,236,000				3,236,000				3,236,000	3,236,000	3,236,000
Additional Paid-in Capital [Member]
Balance				387,876				382,674				363,918	387,876	382,674	363,918
Compensation and benefits paid or payable in shares													314	3,170	4,309
Options exercised													883	576	24
Shares issued to Directors													24	(33)	(220)
Long-term incentive plan													2,398	1,489	571
Stock option expense															70
Convertible notes purchased															(5,202)
Settlement of equity-related tax issues															19,204
Net income/(loss)
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	391,495				387,876				382,674				391,495	387,876	382,674
Retained Earnings [Member]
Balance				403,048				380,335				428,497	403,048	380,335	428,497
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors
Long-term incentive plan
Stock option expense
Convertible notes purchased
Settlement of equity-related tax issues
Net income/(loss)													34,938	37,636	(33,458)
Dividends declared													(15,942)	(14,923)	(14,704)
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	422,044				403,048				380,335				422,044	403,048	380,335
Accumulated Other Comprehensive Income (Loss) [Member]
Balance				(106,672)				(82,136)				(101,953)	(106,672)	(82,136)	(101,953)
Compensation and benefits paid or payable in shares
Options exercised
Shares issued to Directors
Long-term incentive plan
Stock option expense
Convertible notes purchased
Settlement of equity-related tax issues
Net income/(loss)
Dividends declared
Cumulative translation adjustments													(13,070)	(10,208)	38,363
Pension and postretirement liability adjustments													(17,749)	(14,052)	(18,546)
Derivative valuation adjustment													(2,318)	(276)
Balance	(139,809)				(106,672)				(82,136)				(139,809)	(106,672)	(82,136)
Treasury Stock [Member]
Balance				(258,031)				(258,299)				(258,871)	(258,031)	(258,299)	(258,871)
Balance, shares				8,485,000				8,497,000				8,523,000	8,485,000	8,497,000	8,523,000
Compensation and benefits paid or payable in shares
Compensation and benefits paid or payable in shares, shares
Options exercised
Options exercised, shares
Shares issued to Directors													111	268	572
Shares issued to Directors, shares													(5,000)	(12,000)	(26,000)
Long-term incentive plan
Long-term incentive plan, shares
Stock option expense
Convertible notes purchased
Settlement of equity-related tax issues
Net income/(loss)
Dividends declared
Cumulative translation adjustments
Pension and postretirement liability adjustments
Derivative valuation adjustment
Balance	$ (257,920)				$ (258,031)				$ (258,299)				$ (257,920)	$ (258,031)	$ (258,299)
Balance, shares	8,480,000				8,485,000				8,497,000				8,480,000	8,485,000	8,497,000