Accounting for Certain Loans Acquired in a Transfer - Carrying amount of loans included in balance sheet of loans receivable (Details) (Loans Receivable, USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Carrying balance of acquired credit-impaired loans	$ 2,857	$ 3,103
Construction/Land
Business Acquisition [Line Items]
Carrying balance of acquired credit-impaired loans	337	301
One-to-four family residential
Business Acquisition [Line Items]
Carrying balance of acquired credit-impaired loans	1,281	1,420
Multi-family residential
Business Acquisition [Line Items]
Carrying balance of acquired credit-impaired loans	500	451
Nonresidential real estate and agricultural land
Business Acquisition [Line Items]
Carrying balance of acquired credit-impaired loans	705	863
Commercial
Business Acquisition [Line Items]
Carrying balance of acquired credit-impaired loans	15	38
Dupont State Bank
Business Acquisition [Line Items]
Outstanding balance of acquired credit-impaired loans	4,398	5,222
Fair value adjustment for credit-impaired loans	(1,541)	(2,119)
Carrying balance of acquired credit-impaired loans	2,857	3,103
Dupont State Bank | Construction/Land
Business Acquisition [Line Items]
Outstanding balance of acquired credit-impaired loans	713	750
Dupont State Bank | One-to-four family residential
Business Acquisition [Line Items]
Outstanding balance of acquired credit-impaired loans	1,812	2,149
Dupont State Bank | Multi-family residential
Business Acquisition [Line Items]
Outstanding balance of acquired credit-impaired loans	685	685
Dupont State Bank | Nonresidential real estate and agricultural land
Business Acquisition [Line Items]
Outstanding balance of acquired credit-impaired loans	1,124	1,523
Dupont State Bank | Commercial
Business Acquisition [Line Items]
Outstanding balance of acquired credit-impaired loans	26	64
Dupont State Bank | Consumer and other
Business Acquisition [Line Items]
Outstanding balance of acquired credit-impaired loans	$ 38	$ 51