Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at Dec. 31, 2009	$ 87,182	$ 746,775	$ 30,235	$ (20,366)	$ 843,826
Comprehensive income
Net income	0	0	38,214	0	38,214
Other comprehensive income
Change in unrealized gain (loss) on securities available for sale, net of reclassification and tax	0	0	0	11,501	11,501
Transferred securities, net of tax	0	0	0	4,855	4,855
Reclassification adjustment on cash flows hedges, net of tax	0	0	0	659	659
Net loss, settlement cost and amortization of net (gain) loss on defined benefit pension plans, net of tax	0	0	0	2,082	2,082
Dividends - common stock	0	0	(24,361)	0	(24,361)
Common stock issued	19	178	0	0	197
Common stock repurchased	(41)	(664)	0	0	(705)
Stock based compensation expense	0	2,369	0	0	2,369
Stock activity under incentive comp plans	23	215	(70)	0	168
Balance at Dec. 31, 2010	87,183	748,873	44,018	(1,269)	878,805
Comprehensive income
Net income	0	0	72,460	0	72,460
Other comprehensive income
Change in unrealized gain (loss) on securities available for sale, net of reclassification and tax	0	0	0	20,823	20,823
Transferred securities, net of tax	0	0	0	(922)	(922)
Reclassification adjustment on cash flows hedges, net of tax	0	0	0	(701)	(701)
Net loss, settlement cost and amortization of net (gain) loss on defined benefit pension plans, net of tax	0	0	0	(2,927)	(2,927)
Acquisition	7,575	82,495			90,070
Dividends - common stock	0	0	(26,513)	0	(26,513)
Common stock issued	22	200	0	0	222
Common stock repurchased	(145)	(1,381)	0	0	(1,526)
Stock based compensation expense	0	3,436	0	0	3,436
Stock activity under incentive comp plans	19	410	(100)	0	329
Balance at Dec. 31, 2011	94,654	834,033	89,865	15,004	1,033,556
Comprehensive income
Net income	0	0	91,675	0	91,675
Other comprehensive income
Change in unrealized gain (loss) on securities available for sale, net of reclassification and tax	0	0	0	14,441	14,441
Transferred securities, net of tax	0	0	0	(1,476)	(1,476)
Reclassification adjustment on cash flows hedges, net of tax	0	0	0	(144)	(144)
Net loss, settlement cost and amortization of net (gain) loss on defined benefit pension plans, net of tax	0	0	0	1,976	1,976
Acquisition	6,626	81,871	0	0	88,497
Dividends - common stock	0	0	(34,657)	0	(34,657)
Common stock issued	21	233	0	0	254
Common stock repurchased	(326)	(3,664)	0	0	(3,990)
Stock based compensation expense	0	3,317	0	0	3,317
Stock activity under incentive comp plans	204	1,128	(216)	0	1,116
Balance at Dec. 31, 2012	$ 101,179	$ 916,918	$ 146,667	$ 29,801	$ 1,194,565