Consolidated Statement of Changes in Shareholders' Equity (USD $) In Thousands	Total	Common stock [Member]	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income	Treasury stock
Balance at Dec. 31, 2011	$ 3,273,982	$ 122,720	$ 1,001,308	$ 2,429,818	$ 227,659	$ (507,523)
Net earnings	176,077			176,077
Other comprehensive income (loss)	32,117				32,117
Issuance of 516 shares for exercise of options, including tax effect	13,644	516	13,128
Purchase of 4,093 common shares	(126,426)					(126,426)
Stock-based compensation	5,347	213	5,134
Cash dividends declared $0.31 per share	(31,484)			(31,484)
Balance at Jun. 30, 2012	$ 3,343,257	$ 123,449	$ 1,019,570	$ 2,574,411	$ 259,776	$ (633,949)