Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Consolidated Statements of Changes in Shareholders' Equity (Unaudited) [Abstract]
Balance, January 1,	$ 1,354,953	$ 1,287,369
Net income per consolidated statements of income	95,489	89,021
Other comprehensive income (loss)	9,366	(55,621)
Common stock dividends paid	(46,852)	(46,674)
Common stock issued-net, long-term incentive plans:
Stock options	0	845
Restricted stock	(795)	(963)
Excess tax expense from stock-based compensation arrangements	(353)	(808)
Compensation expense, long-term incentive plans	3,290	2,850
Common stock issued, business combinations	0	53,495
Balance, September 30,	$ 1,415,098	$ 1,329,514