Shareholders' Equity (Schedule of Activity in Shareholders' Equity) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Balance	$ 493,511
Net income	11,511	47,041
Dividends declared	(4,421)
Compensation and benefits paid or payable in shares	(698)
Options exercised	2,315
Cumulative translation adjustment	(11,288)
Change in pension liability adjustment	1,169
Change in derivative valuation adjustment	279
Balance	492,378
Common Class A [Member]
Balance	37
Net income
Dividends declared
Compensation and benefits paid or payable in shares
Options exercised
Cumulative translation adjustment
Change in pension liability adjustment
Change in derivative valuation adjustment
Balance	37
Common Class B [Member]
Balance	3
Net income
Dividends declared
Compensation and benefits paid or payable in shares
Options exercised
Cumulative translation adjustment
Change in pension liability adjustment
Change in derivative valuation adjustment
Balance	3
Additional Paid-in Capital [Member]
Balance	395,381
Net income
Dividends declared
Compensation and benefits paid or payable in shares	(698)
Options exercised	2,315
Cumulative translation adjustment
Change in pension liability adjustment
Change in derivative valuation adjustment
Balance	396,998
Retained Earnings [Member]
Balance	435,775
Net income	11,511
Dividends declared	(4,421)
Compensation and benefits paid or payable in shares
Options exercised
Cumulative translation adjustment
Change in pension liability adjustment
Change in derivative valuation adjustment
Balance	442,865
Accumulated Other Comprehensive Income [Member]
Balance	(80,021)
Net income
Dividends declared
Compensation and benefits paid or payable in shares
Options exercised
Cumulative translation adjustment	(11,288)
Change in pension liability adjustment	1,169
Change in derivative valuation adjustment	279
Balance	(89,861)
Treasury Stock [Member]
Balance	(257,664)
Net income
Dividends declared
Compensation and benefits paid or payable in shares
Options exercised
Cumulative translation adjustment
Change in pension liability adjustment
Change in derivative valuation adjustment
Balance	$ (257,664)