Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Consolidated Statements of Changes in Shareholders' Equity (Unaudited) [Abstract]
Balance, January 1,	$ 1,215,037	$ 1,149,484
Net income per consolidated statements of income	59,669	55,615
Other comprehensive income	533	15,100
Common stock dividends paid	(29,921)	(29,740)
Common stock issued-net, long-term incentive plans:
Stock options	184	1,507
Restricted stock	(1,197)	(1,868)
Excess tax benefit from stock-based compensation arrangements	49	630
Compensation expense, long-term incentive plans	2,141	2,042
Common stock issued, business combinations	12,000	0
Balance, June 30,	$ 1,258,495	$ 1,192,770