Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 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	61,900	55,987
Other comprehensive income (loss)	13,174	(39,483)
Common stock dividends paid	(31,224)	(31,108)
Common stock issued-net, long-term incentive plans:
Stock options	0	381
Restricted stock	(795)	(949)
Excess tax expense from stock-based compensation arrangements	(353)	(747)
Compensation expense, long-term incentive plans	2,236	1,874
Common stock issued, business combinations	0	53,495
Balance, June 30,	$ 1,399,891	$ 1,326,819