Loans - Schedule of Loans Renegotiated in Troubled Debt Restructurings (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 notes	Dec. 31, 2011 notes
Loans and Leases Receivable, Troubled Debt Restructuring
Loans renegotiated in troubled debt restructurings	$ 76,597	$ 94,827
Loans renegotiated in troubled debt restructurings, non-accrual loans	44,665	57,451
Loans tenegotiated in troubled debt restructurings, accrual loans	31,932	37,376
Financing receivable, modifications, subsequent default, number of contracts, during period	38	137
Principle balance at restructure date	22,760	85,143
Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	955	57,835
Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	2,704	10,790
Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	6,494	5,119
Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	12,607	11,399
Commercial real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period	16	60
Principle balance at restructure date	14,074	38,921
Commercial real estate | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	23,982
Commercial real estate | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	959	4,444
Commercial real estate | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	4,504	3,131
Commercial real estate | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	8,611	7,364
Commercial construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period	1
Principle balance at restructure date	3,155
Commercial construction real estate | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0
Commercial construction real estate | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0
Commercial construction real estate | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0
Commercial construction real estate | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	3,155
Land acquisition & development construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period	5	9
Principle balance at restructure date	3,380	6,207
Land acquisition & development construction real estate | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	995
Land acquisition & development construction real estate | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	1,000	4,124
Land acquisition & development construction real estate | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	1,757	680
Land acquisition & development construction real estate | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	623	408
Residential construction real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period	2	5
Principle balance at restructure date	513	8,861
Residential construction real estate | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	7,749
Residential construction real estate | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	280	878
Residential construction real estate | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	233	234
Residential construction real estate | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	0
Total construction loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period	8	14
Principle balance at restructure date	7,048	15,068
Total construction loans | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	8,744
Total construction loans | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	1,280	5,002
Total construction loans | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	1,990	914
Total construction loans | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	3,778	408
Residential real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period	2	6
Principle balance at restructure date	593	10,948
Residential real estate | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	568	9,771
Residential real estate | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	25	364
Residential real estate | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	223
Residential real estate | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	590
Agricultural real estate
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period	1	7
Principle balance at restructure date	154	4,540
Agricultural real estate | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	3,594
Agricultural real estate | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	154	517
Agricultural real estate | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	189
Agricultural real estate | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	240
Total real estate loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period	27	87
Principle balance at restructure date	21,869	69,477
Total real estate loans | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	568	46,091
Total real estate loans | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	2,418	10,327
Total real estate loans | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	6,494	4,457
Total real estate loans | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	12,389	8,602
Indirect consumer
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period		2
Principle balance at restructure date		29
Indirect consumer | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date		0
Indirect consumer | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date		0
Indirect consumer | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date		0
Indirect consumer | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date		29
Other consumer
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period	1	3
Principle balance at restructure date	69	78
Other consumer | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	17
Other consumer | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	69	11
Other consumer | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	0
Other consumer | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	50
Total consumer loans
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period	1	5
Principle balance at restructure date	69	107
Total consumer loans | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	17
Total consumer loans | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	69	11
Total consumer loans | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	0
Total consumer loans | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	79
Commercial
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period	10	40
Principle balance at restructure date	822	15,372
Commercial | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	387	11,727
Commercial | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	217	428
Commercial | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	662
Commercial | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	218	2,555
Agricultural
Loans and Leases Receivable, Troubled Debt Restructuring
Financing receivable, modifications, subsequent default, number of contracts, during period	0	5
Principle balance at restructure date	0	187
Agricultural | Interest only period
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date		0
Agricultural | Extension of terms or maturity
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	0	24
Agricultural | Interest rate adjustment
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date		0
Agricultural | Other
Loans and Leases Receivable, Troubled Debt Restructuring
Principle balance at restructure date	$ 0	$ 163