Consolidated Statements Of Changes In Shareholders Equity (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Total shareholders' equity at beginning of period	$ 2,283,537	$ 2,061,680
Net income	177,764	162,121
Other comprehensive income	26,989	89,803
Stock option exercises (197,961 shares in 2012 and 144,203 shares in 2011)	10,092	7,239
Stock compensation expense recognized in earnings	7,942	10,016
Tax benefits (deficiencies) related to stock compensation	(425)	304
Purchase of treasury stock (29,823 shares in 2011)		(1,657)
Common stock issued/sold to the 401(k) stock purchase plan (22,680 shares in 2011)		1,360
Cash dividends ($1.42 per share in 2012 and $1.37 per share in 2011)	(87,282)	(83,990)
Total shareholders' equity at end of period	$ 2,418,617	$ 2,246,876