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, 2012	$ 3,542,612	$ 125,114	$ 1,052,253	$ 2,756,166	$ 295,271	$ (686,192)
Net earnings	194,012			194,012
Other Comprehensive Loss Net Of Tax	(169,152)				(169,152)
Issuance of 250 shares for exercise of options, including tax effect	7,408	250	7,158
Purchase of 1,024 common shares	(40,929)					(40,929)
Stock-based compensation	4,524	(14)	4,538
Cash dividends declared, $0.33 per share	(33,092)			(33,092)
Balance at Jun. 30, 2013	$ 3,505,383	$ 125,350	$ 1,063,949	$ 2,917,086	$ 126,119	$ (727,121)