Loans and Asset Quality Information (Details 11) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment	$ 53,421	$ 47,245	$ 53,473
Imapired loans with no related allowance - Unpaid Principal Balance	98,838	84,187
Impaired loans with no related allowance - Average Recorded Investment	50,333	63,546
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment	71,677	59,593
Impaired loans with allowance - Unpaid Principal Balance	81,727	71,062
Impaired loans with related allowance - Related Allowance	9,781	8,560	16,970
Impaired loans with related allowance - Average Recorded Investment	65,636	76,425
Non-covered
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment		12,049
Imapired loans with no related allowance - Unpaid Principal Balance		12,774
Impaired loans with no related allowance - Average Recorded Investment		24,174
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment		45,833
Impaired loans with allowance - Unpaid Principal Balance		52,791
Impaired loans with related allowance - Related Allowance		5,051
Impaired loans with related allowance - Average Recorded Investment		61,024
Covered
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment		35,196
Imapired loans with no related allowance - Unpaid Principal Balance		71,413
Impaired loans with no related allowance - Average Recorded Investment		39,372
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment		13,760
Impaired loans with allowance - Unpaid Principal Balance		18,271
Impaired loans with related allowance - Related Allowance		3,509
Impaired loans with related allowance - Average Recorded Investment		15,401
Non-covered
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment	8,573	12,049	16,717
Imapired loans with no related allowance - Unpaid Principal Balance	9,614
Impaired loans with no related allowance - Average Recorded Investment	10,311
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment	54,722
Impaired loans with allowance - Unpaid Principal Balance	60,228
Impaired loans with related allowance - Related Allowance	5,920	5,051	11,662
Impaired loans with related allowance - Average Recorded Investment	50,278
Non-covered | Commercial Unsecured
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment
Imapired loans with no related allowance - Unpaid Principal Balance
Impaired loans with no related allowance - Average Recorded Investment
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment	26	307
Impaired loans with allowance - Unpaid Principal Balance	27	386
Impaired loans with related allowance - Related Allowance	5	58
Impaired loans with related allowance - Average Recorded Investment	167	221
Non-covered | Commercial Secured
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment
Imapired loans with no related allowance - Unpaid Principal Balance
Impaired loans with no related allowance - Average Recorded Investment		87
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment	2,382	2,398
Impaired loans with allowance - Unpaid Principal Balance	2,761	2,762
Impaired loans with related allowance - Related Allowance	368	436
Impaired loans with related allowance - Average Recorded Investment	2,390	2,304
Non-covered | Secured by Inventory and Accounts Receivable
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment
Imapired loans with no related allowance - Unpaid Principal Balance
Impaired loans with no related allowance - Average Recorded Investment		5
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment	23	17
Impaired loans with allowance - Unpaid Principal Balance	49	43
Impaired loans with related allowance - Related Allowance	6	4
Impaired loans with related allowance - Average Recorded Investment	20	548
Non-covered | Real Estate construction, land development and other land loans
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment	1,550	4,277
Imapired loans with no related allowance - Unpaid Principal Balance	1,552	4,305
Impaired loans with no related allowance - Average Recorded Investment	2,914	8,600
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment	7,764	3,934
Impaired loans with allowance - Unpaid Principal Balance	9,631	5,730
Impaired loans with related allowance - Related Allowance	1,790	1,213
Impaired loans with related allowance - Average Recorded Investment	5,849	12,199
Non-covered | Real estate residential, farmland and mutli-family
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment		1,597
Imapired loans with no related allowance - Unpaid Principal Balance		1,618
Impaired loans with no related allowance - Average Recorded Investment	799	2,692
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment	28,334	23,859
Impaired loans with allowance - Unpaid Principal Balance	28,668	25,844
Impaired loans with related allowance - Related Allowance	2,283	1,955
Impaired loans with related allowance - Average Recorded Investment	26,096	27,186
Non-covered | Real estate home equity lines of credit
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment
Imapired loans with no related allowance - Unpaid Principal Balance
Impaired loans with no related allowance - Average Recorded Investment		64
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment	1,501	1,645
Impaired loans with allowance - Unpaid Principal Balance	1,984	2,120
Impaired loans with related allowance - Related Allowance	90	96
Impaired loans with related allowance - Average Recorded Investment	1,573	2,901
Non-covered | Real estate commercial
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment	7,023	6,175
Imapired loans with no related allowance - Unpaid Principal Balance	8,062	6,851
Impaired loans with no related allowance - Average Recorded Investment	6,598	12,724
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment	13,782	10,851
Impaired loans with allowance - Unpaid Principal Balance	15,851	13,048
Impaired loans with related allowance - Related Allowance	1,239	936
Impaired loans with related allowance - Average Recorded Investment	12,317	12,863
Non-covered | Consumer
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment
Imapired loans with no related allowance - Unpaid Principal Balance
Impaired loans with no related allowance - Average Recorded Investment		2
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment	910	2,822
Impaired loans with allowance - Unpaid Principal Balance	1,257	2,858
Impaired loans with related allowance - Related Allowance	139	353
Impaired loans with related allowance - Average Recorded Investment	1,866	2,802
Covered
Loans with no related allowance recorded:
Impaired loans with no related allowance - Recorded Investment	44,848	35,196	36,756
Imapired loans with no related allowance - Unpaid Principal Balance	89,224
Impaired loans with no related allowance - Average Recorded Investment	40,022
Loans with an allowance recorded:
Impaired loans with allowance - Recorded Investment	16,955
Impaired loans with allowance - Unpaid Principal Balance	21,499
Impaired loans with related allowance - Related Allowance	3,861	3,509	5,308
Impaired loans with related allowance - Average Recorded Investment	$ 15,358