Consolidated Statements Of Shareholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings (Accumulated Deficit) [Member]
Shareholders' Equity at Dec. 31, 2011	$ 1,938,615	$ 3,826	$ 2,986,240	$ (1,306)	$ (1,050,145)
Shareholders' Equity, shares at Dec. 31, 2011		382,608,000
Stock option exercises, shares		2,877,000
Stock option exercises	32,809	29	32,780	0	0
Stock awards, net of cancellations, shares		1,228,000
Stock awards, net of cancellations		12	(12)
Stock repurchases, shares		(105,000)
Stock repurchases	(961)	(1)	(813)		(147)
Stock-based compensation	12,694	0	12,694	0	0
Net income	206,145				206,145
Other comprehensive income	314			314
Shareholders' Equity at Dec. 31, 2012	2,189,616	3,866	3,030,889	(992)	(844,147)
Shareholders' Equity, shares at Dec. 31, 2012		386,608,000
Stock option exercises, shares		1,432,000
Stock option exercises	19,411	14	19,397	0	0
Stock awards, net of cancellations, shares		1,002,000
Stock awards, net of cancellations		10	(10)
Dividends declared	(57,530)				(57,530)
Stock repurchases, shares		(7,742,000)
Stock repurchases	(127,661)	(77)	(3,063)		(124,521)
Stock-based compensation	14,474	0	14,474	0	0
Excess tax benefits (deficiencies) from stock-based compensation	(9,671)		(9,671)
Net income	2,620,116				2,620,116
Other comprehensive income	197			197
Shareholders' Equity at Dec. 31, 2013	4,648,952	3,813	3,052,016	(795)	1,593,918
Shareholders' Equity, shares at Dec. 31, 2013	381,299,600	381,300,000
Stock option exercises, shares		1,422,000
Stock option exercises	15,627	14	15,613	0	0
Stock awards, net of cancellations, shares		(43,000)
Dividends declared	(86,370)		72		(86,442)
Stock repurchases, shares		(13,220,000)
Stock repurchases	(253,019)	(132)			(252,887)
Stock-based compensation	13,812	0	13,786	0	26
Excess tax benefits (deficiencies) from stock-based compensation	(8,491)		(8,491)
Net income	474,338				474,338
Other comprehensive income	105			105
Shareholders' Equity at Dec. 31, 2014	$ 4,804,954	$ 3,695	$ 3,072,996	$ (690)	$ 1,728,953
Shareholders' Equity, shares at Dec. 31, 2014	369,458,530	369,459,000