Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Consolidated Statements of Changes in Shareholders' Equity (Unaudited) [Abstract]
Balance, January 1,	$ 1,287,369	$ 1,215,037
Net income per consolidated statements of income	89,021	89,573
Other comprehensive (loss) income	(55,621)	4,127
Common stock dividends paid	(46,674)	(44,941)
Common stock issued-net, long-term incentive plans:
Stock options	845	268
Restricted stock	(963)	(1,203)
Excess tax (expense) benefit from stock-based compensation arrangements	(808)	35
Compensation expense, long-term incentive plan	2,850	3,119
Common stock issued, business combination	53,495	12,000
Balance, End of Period	$ 1,329,514	$ 1,278,015