Consolidated Statements of Changes in Shareholders’ Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at beginning of period at Dec. 31, 2008	$ 572,093	$ 672	$ 298,984	$ 323,665	$ (51,228)
Comprehensive income (loss)
Net income	(6,528)			(6,528)
Other comprehensive income, net of tax:
Foreign currency translation adjustments	20,159				20,159
Realized gain from cumulative translation adjustment on disposal of foreign business	(3,414)				(3,414)
Net unrealized (losses) gains related to defined benefit pension plans	(3,873)				(3,873)
Amortization of previously unrecognized prior service costs and net losses related to defined benefit pension plans	9				9
Total comprehensive income	6,353
Stock options exercised	5,338	3	5,335
Common stock shares withheld to satisfy employee tax obligations	(3,385)	(3)	(3,382)
Restricted stock units issued as per contractual employment arrangements	848		848
Amortization of share-based payments	20,206		19,330	876
Net tax (shortfall) benefit associated with the vesting of restricted stock shares and stock option exercises	(4,472)		(4,472)
Shares issued to directors	438		438
Cash dividends declared	(20,434)			(20,434)
Balance at end of period at Dec. 31, 2009	576,985	672	317,081	297,579	(38,347)
Comprehensive income (loss)
Net income	160,950			160,950
Other comprehensive income, net of tax:
Foreign currency translation adjustments	(4,342)				(4,342)
Net unrealized (losses) gains related to defined benefit pension plans	23,732				23,732
Amortization of previously unrecognized prior service costs and net losses related to defined benefit pension plans	9				9
Total comprehensive income	180,349
Stock options exercised	9,962	6	9,956
Common stock shares withheld to satisfy employee tax obligations	(6,601)	(3)	(6,598)
Net restricted stock forfeited and restricted stock units vested	0	(2)	2
Restricted stock units issued as per contractual employment arrangements	1,035		1,035
Amortization of share-based payments	20,189		20,381	(192)
Net tax (shortfall) benefit associated with the vesting of restricted stock shares and stock option exercises	2,555		2,555
Shares issued to directors	654		654
Cash dividends declared	(13,620)			(13,620)
Balance at end of period at Dec. 31, 2010	771,508	673	345,066	444,717	(18,948)
Comprehensive income (loss)
Net income	171,416			171,416
Other comprehensive income, net of tax:
Foreign currency translation adjustments	(7,006)				(7,006)
Net unrealized (losses) gains related to defined benefit pension plans	(27,964)				(27,964)
Total comprehensive income	136,446
Stock options exercised	2,566	1	2,565
Common stock shares withheld to satisfy employee tax obligations	(18,575)	(2)	(18,573)
Net restricted stock forfeited and restricted stock units vested	0	3	(3)
Restricted stock units issued as per contractual employment arrangements	149		149
Amortization of share-based payments	18,918		18,918
Net tax (shortfall) benefit associated with the vesting of restricted stock shares and stock option exercises	6,982		6,982
Net impact of Convertible Notes conversions	(374)		(374)
Shares issued to directors	898		898
Cash dividends declared	(14,851)			(14,851)
Balance at end of period at Dec. 31, 2011	$ 903,667	$ 675	$ 355,628	$ 601,282	$ (53,918)