Unaudited Condensed Consolidated Statements Of Shareholders' Equity (USD $) In Thousands	Total	Share Capital [Member]	Additional Paid-In Capital [Member]		Treasury Shares [Member]		Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]
Balance, at beginning of period at Dec. 31, 2011	$ 3,149,022	$ 557,153	$ 78,225		$ (136,590)		$ 14,484	$ 2,635,750
Net income	314,507							314,507
Dividends - par value reduction	(13,701)	(13,701)
Other comprehensive loss	(13,070)						(13,070)
Stock compensation	6,601		(25,410)	[1]	32,011	[1]
Share repurchases	(159,458)				(159,458)
Balance, at end of period at Jun. 30, 2012	3,283,901	543,452	52,815		(264,037)		1,414	2,950,257
Balance, at beginning of period at Dec. 31, 2012	3,326,335	454,980	0		(113,818)		0	2,985,173
Net income	157,130							157,130
Dividends - par value reduction	(12,981)	(12,981)
Dividends	(17,127)							(17,127)
Other comprehensive loss	0						0
Stock compensation	2,443		0	[1]	22,157	[1]		(19,714)	[1]
Share repurchases	(82,571)				(82,571)
Shares cancelled	0	(11,602)	0		82,571			(70,969)
Balance, at end of period at Jun. 30, 2013	$ 3,373,229	$ 430,397	$ 0		$ (91,661)		$ 0	$ 3,034,493

[1] Includes stock compensation expense for the period and shares issued out of treasury for awards exercised or vested.