Loans and the Allowance for Credit Losses (Details 1) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Summary of Changes in the Allowance for Credit Losses
Allowance for loan losses, beginning balance	$ 54,810	$ 61,051
Allowance for loan commitments, beginning balance	468	1,404
Total beginning allowance for credit losses	55,278	62,455
Provision for loan losses	12,222	15,542
Provision for loan commitments	(117)	(699)
Total provision for credit losses	12,105	14,843
Charge-offs	(15,282)	(17,325)
Recoveries	1,860	2,150
Net charge-offs	(13,422)	(15,175)
Allowance for loan losses, ending balance	53,610	61,418
Allowance for loan commitments, ending balance	351	705
Total ending allowance for credit losses	53,961	62,123
Commercial Real Estate Land and Construction [Member]
Summary of Changes in the Allowance for Credit Losses
Allowance for loan losses, beginning balance	4,842	4,701
Allowance for loan commitments, beginning balance	74	1,037
Total beginning allowance for credit losses	4,916	5,738
Provision for loan losses	2,969	4,893
Provision for loan commitments	(25)	(696)
Total provision for credit losses	2,944	4,197
Charge-offs	(3,377)	(4,532)
Recoveries	41	33
Net charge-offs	(3,336)	(4,499)
Allowance for loan losses, ending balance	4,475	5,095
Allowance for loan commitments, ending balance	49	341
Total ending allowance for credit losses	4,524	5,436
Commercial Real Estate Improved Property [Member]
Summary of Changes in the Allowance for Credit Losses
Allowance for loan losses, beginning balance	24,748	30,836
Allowance for loan commitments, beginning balance	21	285
Total beginning allowance for credit losses	24,769	31,121
Provision for loan losses	3,600	3,196
Provision for loan commitments	(11)	(275)
Total provision for credit losses	3,589	2,921
Charge-offs	(4,214)	(4,156)
Recoveries	587	725
Net charge-offs	(3,627)	(3,431)
Allowance for loan losses, ending balance	24,721	30,601
Allowance for loan commitments, ending balance	10	10
Total ending allowance for credit losses	24,731	30,611
Commercial and Industrial [Member]
Summary of Changes in the Allowance for Credit Losses
Allowance for loan losses, beginning balance	11,414	10,793
Allowance for loan commitments, beginning balance	323	65
Total beginning allowance for credit losses	11,737	10,858
Provision for loan losses	740	4,138
Provision for loan commitments	(99)	235
Total provision for credit losses	641	4,373
Charge-offs	(2,342)	(3,937)
Recoveries	256	330
Net charge-offs	(2,086)	(3,607)
Allowance for loan losses, ending balance	10,068	11,324
Allowance for loan commitments, ending balance	224	300
Total ending allowance for credit losses	10,292	11,624
Residential Real Estate [Member]
Summary of Changes in the Allowance for Credit Losses
Allowance for loan losses, beginning balance	5,638	5,950
Allowance for loan commitments, beginning balance	4	1
Total beginning allowance for credit losses	5,642	5,951
Provision for loan losses	2,237	1,386
Provision for loan commitments	1	1
Total provision for credit losses	2,238	1,387
Charge-offs	(2,288)	(1,992)
Recoveries	193	248
Net charge-offs	(2,095)	(1,744)
Allowance for loan losses, ending balance	5,780	5,592
Allowance for loan commitments, ending balance	5	2
Total ending allowance for credit losses	5,785	5,594
Home Equity [Member]
Summary of Changes in the Allowance for Credit Losses
Allowance for loan losses, beginning balance	1,962	2,073
Allowance for loan commitments, beginning balance	33	14
Total beginning allowance for credit losses	1,995	2,087
Provision for loan losses	1,125	421
Provision for loan commitments	15	24
Total provision for credit losses	1,140	445
Charge-offs	(655)	(448)
Recoveries	9	9
Net charge-offs	(646)	(439)
Allowance for loan losses, ending balance	2,441	2,055
Allowance for loan commitments, ending balance	48	38
Total ending allowance for credit losses	2,489	2,093
Consumer [Member]
Summary of Changes in the Allowance for Credit Losses
Allowance for loan losses, beginning balance	5,410	5,641
Allowance for loan commitments, beginning balance	13	2
Total beginning allowance for credit losses	5,423	5,643
Provision for loan losses	1,413	930
Provision for loan commitments	2	12
Total provision for credit losses	1,415	942
Charge-offs	(2,017)	(1,840)
Recoveries	613	635
Net charge-offs	(1,404)	(1,205)
Allowance for loan losses, ending balance	5,419	5,366
Allowance for loan commitments, ending balance	15	14
Total ending allowance for credit losses	5,434	5,380
Overdraft [Member]
Summary of Changes in the Allowance for Credit Losses
Allowance for loan losses, beginning balance	796	1,057
Allowance for loan commitments, beginning balance	0	0
Total beginning allowance for credit losses	796	1,057
Provision for loan losses	138	578
Provision for loan commitments	0	0
Total provision for credit losses	138	578
Charge-offs	(389)	(420)
Recoveries	161	170
Net charge-offs	(228)	(250)
Allowance for loan losses, ending balance	706	1,385
Allowance for loan commitments, ending balance	0	0
Total ending allowance for credit losses	$ 706	$ 1,385