Loans and Allowance - Information regarding troubled debt restructurings by class and new troubled debt restructuring (Details 7) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 Loan	Dec. 31, 2011 Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of troubled debt restructuring	1	3
Total Troubled Debt Restructured	$ 43	$ 1,300
Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of troubled debt restructuring	29	20
Total Troubled Debt Restructured	11,552	9,968
Number of Loans	16	9
Current Balance	4,393	4,649
Pre-Modification Recorded Balance	4,527	4,571
Post-Modification Recorded Balance	4,664	4,700
Loans Receivable | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of troubled debt restructuring	1
Total Troubled Debt Restructured	125
Number of Loans	1
Current Balance	125
Pre-Modification Recorded Balance	76
Post-Modification Recorded Balance	100
Loans Receivable | One-to-four family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of troubled debt restructuring	9	10
Total Troubled Debt Restructured	3,629	3,551
Number of Loans	3	4
Current Balance	573	1,358
Pre-Modification Recorded Balance	574	1,364
Post-Modification Recorded Balance	593	1,363
Loans Receivable | Multi-family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of troubled debt restructuring	1	1
Total Troubled Debt Restructured	1,050	1,966
Number of Loans	1	1
Current Balance	1,051	1,966
Pre-Modification Recorded Balance	1,068	1,735
Post-Modification Recorded Balance	1,082	1,987
Loans Receivable | Nonresidential real estate and agricultural land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of troubled debt restructuring	5	5
Total Troubled Debt Restructured	2,210	2,405
Number of Loans		2
Current Balance		1,285
Pre-Modification Recorded Balance		1,408
Post-Modification Recorded Balance		1,285
Loans Receivable | Land not agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of troubled debt restructuring	4	1
Total Troubled Debt Restructured	4,241	1,971
Number of Loans	3
Current Balance	2,359
Pre-Modification Recorded Balance	2,547
Post-Modification Recorded Balance	2,547
Loans Receivable | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of troubled debt restructuring	9	2
Total Troubled Debt Restructured	297	58
Number of Loans	8	1
Current Balance	285	23
Pre-Modification Recorded Balance	262	46
Post-Modification Recorded Balance	342	46
Loans Receivable | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of troubled debt restructuring		1
Total Troubled Debt Restructured		17
Number of Loans		1
Current Balance		17
Pre-Modification Recorded Balance		18
Post-Modification Recorded Balance		$ 19