CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Capital Surplus	Retained Earnings	Accumulated Other Comprehensive Income/(Loss)	Common Stock In Treasury
Beginning Balance at Dec. 31, 2010	$ 128,070	$ 371	$ 173,935	$ 524,678	$ (4,509)	$ (566,405)
Beginning Balance (in shares) at Dec. 31, 2010		37,069,000				(7,076,000)
Net income	164,386			164,386
Other comprehensive income:
Prior service costs, net of income tax	(422)				(422)
Net actuarial pension loss, net of income tax	580				580
Unrealized gain (loss)	(87)				(87)
Comprehensive income	164,457
Exercise of stock options and equity awards	4,983			(4,160)		9,143
Exercise of stock options and equity awards (in shares)						138,000
Tax benefit from exercise of stock options and equity award vesting	989		989
Stock-based compensation	7,030		7,030
Common shares repurchased (in shares)	(3,100,000)					(3,100,000)
Common shares repurchased	(218,520)					(218,520)
Issuance of shares for Directors' compensation (in shares)						1,000
Issuance of shares for Directors' compensation	30			1		29
Shares tendered for taxes (in shares)						(9,000)
Shares tendered for taxes	(564)					(564)
Ending Balance at Jun. 30, 2011	86,475	371	181,954	684,905	(4,438)	(776,317)
Ending Balance (in shares) at Jun. 30, 2011		37,069,000				(10,046,000)
Net income	143,366			143,366
Other comprehensive income:
Prior service costs, net of income tax	(526)				(526)
Net actuarial pension loss, net of income tax	(5,276)				(5,276)
Pension settlement loss, net of $470 of income tax	734				734
Unrealized gain (loss)	27				27
Comprehensive income	138,325
Exercise of stock options and equity awards	616			(596)		1,212
Exercise of stock options and equity awards (in shares)						17,000
Tax benefit from exercise of stock options and equity award vesting	201		201
Stock-based compensation	7,418		7,418
Common shares repurchased (in shares)						(940,000)
Common shares repurchased	(64,181)					(64,181)
Shares tendered for taxes	(55)					(55)
Ending Balance at Dec. 31, 2011	168,799	371	189,573	827,675	(9,479)	(839,341)
Ending Balance (in shares) at Dec. 31, 2011		37,069,000				(10,969,000)
Net income	107,073			107,073
Other comprehensive income:
Prior service costs, net of income tax	(474)				(474)
Net actuarial pension loss, net of income tax	827				827
Unrealized gain (loss)	(21)				(21)
Comprehensive income	107,405
Exercise of stock options and equity awards	8,091			(8,966)		17,057
Exercise of stock options and equity awards (in shares)						266,000
Tax benefit from exercise of stock options and equity award vesting	930		930
Stock-based compensation	8,309		8,309
Common shares repurchased (in shares)	(3,025,700)					(3,026,000)
Common shares repurchased	(207,918)					(207,918)
Issuance of shares for Directors' compensation (in shares)						1,000
Issuance of shares for Directors' compensation	37			(1)		38
Shares tendered for taxes (in shares)						(22,000)
Shares tendered for taxes	(1,442)					(1,442)
Ending Balance at Jun. 30, 2012	$ 84,211	$ 371	$ 198,812	$ 925,781	$ (9,147)	$ (1,031,606)
Ending Balance (in shares) at Jun. 30, 2012		37,069,000				(13,750,000)