CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY AND COMPREHENSIVE INCOME (LOSS) (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total comprehensive income
Balance at Dec. 31, 2008	$ 1,275,521	$ 562,395	$ 977,736	$ (261,174)	$ (3,436)
Balance (in shares) at Dec. 31, 2008		73,520		(17,151)
Comprehensive income (loss):
Net income (loss)	83,658		83,658			83,658
Proportionate share of other companies foreign currency translation adjustment, net of tax $180, $390 and $596 for the year ended 2011, 2010 and 2009, respectively	972				972	972
Net unrealized appreciation (depreciation) on marketable securities net of tax of $327, $457 and $2,158 for the year ended 2011, 2010 and 2009, respectively	3,774				3,774	3,774
Total comprehensive income (loss)	88,404					88,404
Exercise of common stock options and issuance of restricted stock	215	215
Exercise of common stock options and issuance of restricted stock (in shares)		271
Sale of common stock under employee stock purchase plan	8,572	8,572
Sale of common stock under employee stock purchase plan (in shares)		836
Stock based compensation expense related to the issuance of stock options	7,944	7,944
Tax benefit (deficiency) from exercise of common stock options	(973)	(973)
Treasury stock purchases	(18,445)			(18,445)
Treasury stock purchases (in shares)				(1,867)
Cash dividends declared ($0.16 per share)	(9,019)		(9,019)
Balance at Dec. 31, 2009	1,352,219	578,153	1,052,375	(279,619)	1,310
Balance (in shares) at Dec. 31, 2009		74,627		(19,018)
Comprehensive income (loss):
Net income (loss)	96,350		96,350			96,350
Proportionate share of other companies foreign currency translation adjustment, net of tax $180, $390 and $596 for the year ended 2011, 2010 and 2009, respectively	637				637	637
Net unrealized appreciation (depreciation) on marketable securities net of tax of $327, $457 and $2,158 for the year ended 2011, 2010 and 2009, respectively	(745)				(745)	(745)
Total comprehensive income (loss)	96,242					96,242
Exercise of common stock options and issuance of restricted stock	83	83
Exercise of common stock options and issuance of restricted stock (in shares)		261
Sale of common stock under employee stock purchase plan	4,824	4,824
Sale of common stock under employee stock purchase plan (in shares)		357
Stock based compensation expense related to the issuance of stock options	6,428	6,428
Tax benefit (deficiency) from exercise of common stock options	122	122
Treasury stock purchases	(30,009)			(30,009)
Treasury stock purchases (in shares)				(2,054)
Cash dividends declared ($0.16 per share)	(8,986)		(8,986)
Balance at Dec. 31, 2010	1,420,923	589,610	1,139,739	(309,628)	1,202
Balance (in shares) at Dec. 31, 2010		75,245		(21,072)
Comprehensive income (loss):
Net income (loss)	(27,335)		(27,335)			(27,335)
Proportionate share of other companies foreign currency translation adjustment, net of tax $180, $390 and $596 for the year ended 2011, 2010 and 2009, respectively	(295)				(295)	(295)
Net unrealized appreciation (depreciation) on marketable securities net of tax of $327, $457 and $2,158 for the year ended 2011, 2010 and 2009, respectively	534				534	534
Total comprehensive income (loss)	(27,096)					(27,096)
Exercise of common stock options and issuance of restricted stock	70	70
Exercise of common stock options and issuance of restricted stock (in shares)		289
Sale of common stock under employee stock purchase plan	4,372	4,372
Sale of common stock under employee stock purchase plan (in shares)		300
Stock based compensation expense related to the issuance of stock options	5,365	5,365
Tax benefit (deficiency) from exercise of common stock options	(432)	(432)
Treasury stock purchases	(60,681)			(60,681)
Treasury stock purchases (in shares)				(4,149)
Cash dividends declared ($0.16 per share)	(8,260)		(8,260)
Balance at Dec. 31, 2011	$ 1,334,261	$ 598,985	$ 1,104,144	$ (370,309)	$ 1,441
Balance (in shares) at Dec. 31, 2011		75,834		(25,221)