Business Segments (Financial Information for Segments of the Corporation) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Interest income	$ 98,155	$ 94,361	$ 195,526	$ 186,907
Interest expense	19,461	22,880	39,549	47,021
Net interest income	78,694	71,481	155,977	139,886
Provision for loan losses	8,551	12,239	16,779	24,203
Non-interest income	29,258	28,443	57,690	58,718
Non-interest expense, excluding intangible amortization	66,564	61,405	139,325	125,161
Intangible amortization	1,805	1,679	3,601	3,366
Income tax expense (benefit)	8,670	6,679	14,425	11,972
Net income (loss)	22,362	17,922	39,537	33,902
Total assets	9,857,163	8,833,060	9,857,163	8,833,060	8,959,915
Total intangibles	601,958	564,495	601,958	564,495
Number of reportable segments			4
Community Banking [Member]
Interest income	88,207	85,242	175,990	168,706
Interest expense	15,718	19,215	32,112	39,692
Net interest income	72,489	66,027	143,878	129,014
Provision for loan losses	6,812	10,488	13,648	20,995
Non-interest income	20,726	19,307	40,807	41,955
Non-interest expense, excluding intangible amortization	54,319	50,123	114,376	102,788
Intangible amortization	1,615	1,485	3,221	2,977
Income tax expense (benefit)	8,495	6,291	14,331	11,523
Net income (loss)	21,974	16,947	39,109	32,686
Total assets	9,657,270	8,643,089	9,657,270	8,643,089
Total intangibles	576,786	538,553	576,786	538,553
Wealth Management [Member]
Interest income	3	3	6	6
Net interest income	3	3	6	6
Non-interest income	6,368	5,234	12,306	10,219
Non-interest expense, excluding intangible amortization	4,649	4,174	9,582	8,163
Intangible amortization	83	87	167	175
Income tax expense (benefit)	585	351	918	678
Net income (loss)	1,054	625	1,645	1,209
Total assets	20,485	20,110	20,485	20,110
Total intangibles	11,799	12,142	11,799	12,142
Insurance [Member]
Interest income	33	52	66	107
Net interest income	33	52	66	107
Non-interest income	3,001	3,199	6,559	6,882
Non-interest expense, excluding intangible amortization	2,772	2,969	6,063	5,906
Intangible amortization	107	107	213	214
Income tax expense (benefit)	56	64	126	310
Net income (loss)	99	111	223	559
Total assets	19,366	20,750	19,366	20,750
Total intangibles	11,564	11,991	11,564	11,991
Consumer Finance [Member]
Interest income	8,492	8,124	16,562	16,126
Interest expense	1,064	1,200	2,181	2,457
Net interest income	7,428	6,924	14,381	13,669
Provision for loan losses	1,656	1,577	2,984	2,897
Non-interest income	549	612	1,071	1,186
Non-interest expense, excluding intangible amortization	4,381	3,874	8,705	7,912
Income tax expense (benefit)	769	752	1,452	1,461
Net income (loss)	1,171	1,333	2,311	2,585
Total assets	169,765	166,441	169,765	166,441
Total intangibles	1,809	1,809	1,809	1,809
Parent and Other [Member]
Interest income	1,420	940	2,902	1,962
Interest expense	2,679	2,465	5,256	4,872
Net interest income	(1,259)	(1,525)	(2,354)	(2,910)
Provision for loan losses	83	174	147	311
Non-interest income	(1,386)	91	(3,053)	(1,524)
Non-interest expense, excluding intangible amortization	443	265	599	392
Income tax expense (benefit)	(1,235)	(779)	(2,402)	(2,000)
Net income (loss)	(1,936)	(1,094)	(3,751)	(3,137)
Total assets	$ (9,723)	$ (17,330)	$ (9,723)	$ (17,330)