CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
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)
Increase (Decrease) in Stockholders' Equity
Net (loss) income	96,350		96,350
Proportionate share of other companies foreign currency translation adjustment, net of tax of $154, $180 and $390 and for the year ended 2012, 2011 and 2010, respectively	637				637
Net unrealized appreciation (depreciation) on marketable securities net of tax of $194, $327 and $457 for the year ended 2012, 2011 and 2010, respectively	(745)				(745)
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 and restricted stock	6,428	6,428
Tax (deficiency) benefit 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)
Increase (Decrease) in Stockholders' Equity
Net (loss) income	(27,335)		(27,335)
Proportionate share of other companies foreign currency translation adjustment, net of tax of $154, $180 and $390 and for the year ended 2012, 2011 and 2010, respectively	(295)				(295)
Net unrealized appreciation (depreciation) on marketable securities net of tax of $194, $327 and $457 for the year ended 2012, 2011 and 2010, respectively	534				534
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 and restricted stock	5,365	5,365
Tax (deficiency) benefit 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)
Increase (Decrease) in Stockholders' Equity
Net (loss) income	51,157		51,157
Proportionate share of other companies foreign currency translation adjustment, net of tax of $154, $180 and $390 and for the year ended 2012, 2011 and 2010, respectively	(251)				(251)
Net unrealized appreciation (depreciation) on marketable securities net of tax of $194, $327 and $457 for the year ended 2012, 2011 and 2010, respectively	316				316
Exercise of common stock options and issuance of restricted stock	1,879	1,879
Exercise of common stock options and issuance of restricted stock (in shares)		392
Sale of common stock under employee stock purchase plan	4,068	4,068
Sale of common stock under employee stock purchase plan (in shares)		487
Stock based compensation expense related to the issuance of stock options and restricted stock	4,693	4,693
Tax (deficiency) benefit from exercise of common stock options	138	138
Treasury stock purchases	(902)			(902)
Treasury stock purchases (in shares)				(59)
Cash dividends declared ($0.16 per share)	(8,184)		(8,184)
Balance at Dec. 31, 2012	$ 1,387,175	$ 609,763	$ 1,147,117	$ (371,211)	$ 1,506
Balance (in shares) at Dec. 31, 2012		76,713		(25,280)