Consolidated Statement of Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock [Member]	Common Class B [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Earnings (Loss) [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2010	$ 652,411	$ 8,401	$ 272	$ 231,685	$ 370,001	$ 112,631	$ (70,579)
Exercise of stock options	4,133	45		4,098			(10)
Non-qualified stock option expense	4,441			4,441
Restricted stock awards	1,533	25		2,174			(666)
Net Earnings (loss)	(4,113)				(4,113)
Foreign currency translation adjustments	14,440					14,440
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	254					254
Unrealized gain (loss) on cash flow hedges	305
Defined benefit plans:
Amortization of prior service costs and unrecognized losses and credits	(401)					(401)
Amounts arising during the year, primarily due to the addition of new participants	(2,048)					(2,048)
Marketable securities holding gain (loss)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	8,132
Extinguishment of Convertible Debt	(20,989)			(20,989)
Dividends	(1,588)				(1,588)
Purchase of treasury shares	(21,548)						(21,548)
Ending Balance at Dec. 31, 2011	626,525	8,471	272	221,409	364,300	124,876	(92,803)
Exercise of stock options		2		98			(100)
Non-qualified stock option expense	4,304			4,304
Restricted stock awards	1,882	30		2,211			(359)
Net Earnings (loss)	1,827				1,827
Foreign currency translation adjustments	(9,624)					(9,624)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	(1,677)					(1,677)
Unrealized gain (loss) on cash flow hedges	(1,730)
Defined benefit plans:
Amortization of prior service costs and unrecognized losses and credits	(664)					(664)
Amounts arising during the year, primarily due to the addition of new participants	(168)					(168)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	(10,306)
Extinguishment of Convertible Debt	165			165
Dividends	(1,581)				(1,581)
Ending Balance at Dec. 31, 2012	620,989	8,503	272	228,187	364,546	112,743	(93,262)
Exercise of stock options	499	7		505			(13)
Non-qualified stock option expense	3,925			3,925
Restricted stock awards	1,513	29		2,003			(519)
Net Earnings (loss)	33,051				33,051
Foreign currency translation adjustments	10,969					10,969
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	73					73
Unrealized gain (loss) on cash flow hedges	83
Defined benefit plans:
Amortization of prior service costs and unrecognized losses and credits	1,691					1,691
Amounts arising during the year, primarily due to the addition of new participants	(320)					(320)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	45,464
Dividends	(1,581)				(1,581)
Ending Balance at Dec. 31, 2013	$ 670,809	$ 8,539	$ 272	$ 234,620	$ 396,016	$ 125,156	$ (93,794)