Consolidated Statement of Changes in Shareholders' Equity (USD $) In Thousands	Total	Common stock [Member]	Additional paid-in capital [Member]	Retained earnings [Member]	Accumulated other comprehensive income [Member]	Treasury stock [Member]
Balance at Dec. 31, 2013	$ 3,674,430	$ 125,577	$ 1,073,105	$ 3,085,501	$ 118,651	$ (728,404)
Net earnings	107,911			107,911
Other comprehensive income	43,570				43,570
Issuance of 199 shares for exercise of options, including tax effect	6,806	199	6,607
Issuance of 44 shares for employee stock purchase plan	1,622	44	1,578
Purchase of 736 common shares	(31,413)					(31,413)
Stock-based compensation	1,687	242	1,445
Cash dividends declared, $0.225 per share	(22,500)			(22,500)
Balance at Mar. 31, 2014	$ 3,782,113	$ 126,062	$ 1,082,735	$ 3,170,912	$ 162,221	$ (759,817)