Consolidated Statements of Stockholders’ Equity (USD $) In Thousands, unless otherwise specified	Total	Number of Common Shares	Common Stock and Capital In Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Stockholders' equity, beginning balance at Dec. 31, 2008	$ 799,877		$ 272,717	$ 528,278	$ (1,118)
Common stock shares outstanding, beginning balance at Dec. 31, 2008		292,733
Components of comprehensive Income:
Net Income	251,062	0	0	251,062	0
Amortization of accumulated unamortized loss on retiree medical plan	1,118	0	0	0	1,118
Total comprehensive income	252,180
Issuance of common stock through employee stock plans, net, shares		4,710
Issuance of common stock through employee stock plans, net, value	42,144		42,144	0	0
Restricted stock withholding, shares		(626)
Restricted stock withholding, value	(10,738)		(3,264)	(7,474)	0
Repurchases of common stock, shares	0
Stock-based compensation expense	64,446		64,446	0	0
Tax effect of employee stock plans	(3,648)		(3,648)	0	0
Dividends paid	(58,925)		0	(58,925)	0
Stockholders' equity, ending balance at Dec. 31, 2009	1,085,336		372,395	712,941	0
Common stock shares outstanding, ending balance at Dec. 31, 2009		296,817
Components of comprehensive Income:
Net Income	782,884	0	0	782,884	0
Issuance of common stock through employee stock plans, net, shares		23,460
Issuance of common stock through employee stock plans, net, value	453,808		453,808	0	0
Restricted stock withholding, shares		(783)
Restricted stock withholding, value	(20,164)		(6,457)	(13,707)	0
Repurchases of common stock, shares	0
Stock-based compensation expense	62,118		62,118	0	0
Tax effect of employee stock plans	27,444		27,444	0	0
Dividends paid	(67,774)		0	(67,774)	0
Stockholders' equity, ending balance at Dec. 31, 2010	2,323,652		909,308	1,414,344	0
Common stock shares outstanding, ending balance at Dec. 31, 2010	319,494	319,494
Components of comprehensive Income:
Net Income	770,711	0	0	770,711	0
Change in net unrealized loss on available-for-sale securities, net of tax benefit	(133)	0	0	0	(133)
Total comprehensive income	770,578
Issuance of common stock through employee stock plans, net, shares		8,146
Issuance of common stock through employee stock plans, net, value	119,989		119,989	0	0
Restricted stock withholding, shares		(786)
Restricted stock withholding, value	(32,152)		(10,936)	(21,216)	0
Repurchases of common stock, shares	(4,800)	(4,800)
Repurchases of common stock, value	(197,023)		(66,199)	(130,824)	0
Stock-based compensation expense	82,750		82,750	0	0
Tax effect of employee stock plans	16,162		16,162	0	0
Dividends paid	(90,060)		0	(90,060)	0
Stockholders' equity, ending balance at Dec. 31, 2011	$ 2,993,896		$ 1,051,074	$ 1,942,955	$ (133)
Common stock shares outstanding, ending balance at Dec. 31, 2011	322,054	322,054