Condensed Consolidated Statements Of Shareholders' Equity (USD $) In Thousands	Share Capital [Member]	Additional Paid-In Capital [Member]	Treasury Shares [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]	Total
Shareholders' equity, beginning balance at Dec. 31, 2009	$ 1,492	$ 1,359,934		$ 149,849	$ 1,702,020	$ 3,213,295
Cumulative effect adjustment upon adoption of ASU 2010-11, net of deferred taxes				(41,889)	41,889
Net income					572,219	572,219
Dividends					(28,774)	(28,774)
Other comprehensive income (loss)				3,800		3,800
Stock compensation	32	28,570				28,602
Share repurchases			(415,009)			(415,009)
Repurchase of founder warrants		(32,819)				(32,819)
Shareholders' equity, ending balance at Sep. 30, 2010	1,524	1,355,685	(415,009)	111,760	2,287,354	3,341,314
Shareholders' equity, beginning balance at Dec. 31, 2010	600,055	170,239	(112,811)	57,135	2,361,202	3,075,820
Net income					91,448	91,448
Dividends - par value reduction	(28,600)					(28,600)
Other comprehensive income (loss)				(39,339)		(39,339)
Stock compensation		(42,822)	60,187			17,365
Share repurchases			(60,000)			(60,000)
Repurchase of founder warrants		(53,620)				(53,620)
Shareholders' equity, ending balance at Sep. 30, 2011	$ 571,455	$ 73,797	$ (112,624)	$ 17,796	$ 2,452,650	$ 3,003,074