Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 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	55,987	59,669
Other comprehensive (loss) income	(39,483)	533
Common stock dividends paid	(31,108)	(29,921)
Common stock issued-net, long-term incentive plans:
Stock options	381	184
Restricted stock	(949)	(1,197)
Excess tax benefit from stock-based compensation arrangements	(747)	49
Compensation expense, long-term incentive plan	1,874	2,141
Common stock issued, business combination	53,495	12,000
Balance, End of Period	$ 1,326,819	$ 1,258,495