Loans and Allowance - Corporation's nonaccrual loans (Details 5) (Loans Receivable, USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	$ 10,745	$ 11,514
Construction/Land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	2,148	3,864
One-to-four family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	4,214	3,833
Multi-family residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	1,013	1,073
Nonresidential and agricultural land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	3,132	2,377
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	230	362
Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total nonaccrual loans	$ 8	$ 5