Loans and Allowance - Information pertaining to principal balances and specific reserve allocations for impaired loans, as well as average balances of and interest recognized on impaired loans (Details 6) (Loans Receivable, USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans without a specific allowance, recorded investment	$ 8,650	$ 10,161
Impaired loans without a specific allowance, unpaid principal balance	9,290	11,914
Impaired loans with a specific allowance, recorded Investment	5,453	4,067
Impaired loans with a specific allowance, unpaid principal balance	5,454	4,086
Impaired loans with a related allowance, specific allowance	986	794
Total impaired loans, recorded investment	14,103	14,228
Total impaired loans, unpaid principal balance	14,744	16,000
Total impaired loans, specific allowance	986	794
Construction / Land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans without a specific allowance, recorded investment	2,687	2,870
Impaired loans without a specific allowance, unpaid principal balance	2,687	3,379
Impaired loans with a specific allowance, recorded Investment	1,878	1,882
Impaired loans with a specific allowance, unpaid principal balance	1,878	1,882
Impaired loans with a related allowance, specific allowance	195	195
Total impaired loans, recorded investment	4,565	4,752
Total impaired loans, unpaid principal balance	4,565	5,261
Total impaired loans, specific allowance	195	195
1-4 family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans without a specific allowance, recorded investment	3,006	3,562
Impaired loans without a specific allowance, unpaid principal balance	3,049	3,612
Impaired loans with a specific allowance, recorded Investment	1,438	955
Impaired loans with a specific allowance, unpaid principal balance	1,438	957
Impaired loans with a related allowance, specific allowance	405	310
Total impaired loans, recorded investment	4,444	4,517
Total impaired loans, unpaid principal balance	4,487	4,569
Total impaired loans, specific allowance	405	310
Multi-family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans without a specific allowance, recorded investment	53	53
Impaired loans without a specific allowance, unpaid principal balance	53	54
Impaired loans with a specific allowance, recorded Investment	1,038	1,051
Impaired loans with a specific allowance, unpaid principal balance	1,038	1,061
Impaired loans with a related allowance, specific allowance	196	196
Total impaired loans, recorded investment	1,091	1,104
Total impaired loans, unpaid principal balance	1,091	1,115
Total impaired loans, specific allowance	196	196
Nonresidential real estate and agricultural land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans without a specific allowance, recorded investment	2,463	3,278
Impaired loans without a specific allowance, unpaid principal balance	3,032	4,439
Impaired loans with a specific allowance, recorded Investment	922
Impaired loans with a specific allowance, unpaid principal balance	922
Impaired loans with a related allowance, specific allowance	97
Total impaired loans, recorded investment	3,385	3,278
Total impaired loans, unpaid principal balance	3,954	4,439
Total impaired loans, specific allowance	97
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans without a specific allowance, recorded investment	429	386
Impaired loans without a specific allowance, unpaid principal balance	457	418
Impaired loans with a specific allowance, recorded Investment	177	179
Impaired loans with a specific allowance, unpaid principal balance	178	186
Impaired loans with a related allowance, specific allowance	93	93
Total impaired loans, recorded investment	606	565
Total impaired loans, unpaid principal balance	635	604
Total impaired loans, specific allowance	93	93
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Impaired loans without a specific allowance, recorded investment	12	12
Impaired loans without a specific allowance, unpaid principal balance	12	12
Impaired loans with a specific allowance, recorded Investment
Impaired loans with a specific allowance, unpaid principal balance
Impaired loans with a related allowance, specific allowance
Total impaired loans, recorded investment	12	12
Total impaired loans, unpaid principal balance	12	12
Total impaired loans, specific allowance