Condensed Consolidated Statements Of Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income/Loss [Member]	Common Stock In Treasury [Member]	Total
Balance, value at Dec. 31, 2010	$ 371	$ 173,935	$ 524,678	$ (4,509)	$ (566,405)	$ 128,070
Balance, shares at Dec. 31, 2010	37,069,000				(7,076,000)
Net income			85,386			85,386
Other comprehensive income:
Prior service costs, net of income tax				(211)		(211)
Net actuarial pension loss, net of income tax				290		290
Unrealized (loss)				(133)		(133)
Comprehensive income						85,332
Exercise of stock options and equity awards, value			(2,300)		5,328	3,028
Exercise of stock options and equity awards, shares					84,000
Tax benefit from exercise of stock options and equity award vesting		351				351
Stock-based compensation		3,308				3,308
Common shares repurchased, value					(139,097)	(139,097)
Common shares repurchased, shares					(2,000,000)	(2,000,000)
Issuance of shares for Directors' compensation, value			1		29	30
Issuance of shares for Directors' compensation, shares					1,000
Shares tendered for taxes, value					(553)	(553)
Shares tendered for taxes, shares					(8,000)
Balance, value at Mar. 31, 2011	371	177,594	607,765	(4,563)	(700,698)	80,469
Balance, shares at Mar. 31, 2011	37,069,000				(8,999,000)
Net income			222,366			222,366
Other comprehensive income:
Prior service costs, net of income tax				(737)		(737)
Net actuarial pension loss, net of income tax				(4,986)		(4,986)
Pension settlement loss, net of $470 of income tax				734		734
Unrealized (loss)				73		73
Comprehensive income						217,450
Exercise of stock options and equity awards, value			(2,456)		5,027	2,571
Exercise of stock options and equity awards, shares					71,000
Tax benefit from exercise of stock options and equity award vesting		839				839
Stock-based compensation		11,140				11,140
Common shares repurchased, value					(143,604)	(143,604)
Common shares repurchased, shares					(2,040,000)
Shares tendered for taxes, value					(66)	(66)
Shares tendered for taxes, shares					(1,000)
Balance, value at Dec. 31, 2011	371	189,573	827,675	(9,479)	(839,341)	168,799
Balance, shares at Dec. 31, 2011	37,069,000				(10,969,000)
Net income			61,071			61,071
Other comprehensive income:
Prior service costs, net of income tax				(237)		(237)
Net actuarial pension loss, net of income tax				423		423
Unrealized (loss)				(23)		(23)
Comprehensive income						61,234
Exercise of stock options and equity awards, value			(4,515)		9,183	4,668
Exercise of stock options and equity awards, shares					145,000
Tax benefit from exercise of stock options and equity award vesting		417				417
Stock-based compensation		4,037				4,037
Common shares repurchased, value					(146,657)	(146,657)
Common shares repurchased, shares					(2,097,000)	(2,097,200)
Issuance of shares for Directors' compensation, value			(1)		38	37
Issuance of shares for Directors' compensation, shares					1,000
Shares tendered for taxes, value					(914)	(914)
Shares tendered for taxes, shares					(14,000)
Balance, value at Mar. 31, 2012	$ 371	$ 194,027	$ 884,230	$ (9,316)	$ (977,691)	$ 91,621
Balance, shares at Mar. 31, 2012	37,069,000				(12,934,000)