Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Total
Balance at Dec. 31, 2008	$ 48,319	$ 1,001,392	$ 123,060	$ (34,545)	$ 1,138,226
Net Income	0	0	137,061	0	137,061
Other comprehensive income:
Change in pension benefit plans (net of taxes)	0	0	0	1,221	1,221
Foreign currency translation	0	0	0	107	107
Total comprehensive income					138,389
Tax effect of stock-based compensation	0	(824)	0	0	(824)
Stock-based compensation expense	0	12,462	0	0	12,462
Issuance of Common Stock, net	220	(47)	0	0	173
Balance at Dec. 31, 2009	48,539	1,012,983	260,121	(33,217)	1,288,426
Net Income	0	0	103,500	0	103,500
Other comprehensive income:
Change in pension benefit plans (net of taxes)	0	0	0	(3,053)	(3,053)
Foreign currency translation	0	0	0	230	230
Total comprehensive income					100,677
Common Stock purchased under share repurchase program	(2,165)	(37,226)	0	0	(39,391)
Common Stock dividend declared	0	0	(47,090)	0	(47,090)
Tax effect of stock-based compensation	0	(2,055)	0	0	(2,055)
Stock-based compensation expense	0	12,752	0	0	12,752
Issuance of Common Stock, net	716	(1,041)	0	0	(325)
Balance at Dec. 31, 2010	47,090	985,413	316,531	(36,040)	1,312,994
Net Income	0	0	86,148	0	86,148
Other comprehensive income:
Change in pension benefit plans (net of taxes)	0	0	0	(7,041)	(7,041)
Change in fair value of investments	0	0	0	199	199
Foreign currency translation	0	0	0	(733)	(733)
Total comprehensive income					78,573
Tax effect of stock-based compensation	0	(367)	0	0	(367)
Stock-based compensation expense	0	8,818	0	0	8,818
Issuance of Common Stock, net	239	(430)	0	0	(191)
Balance at Dec. 31, 2011	$ 47,329	$ 993,434	$ 402,679	$ (43,615)	$ 1,399,827