Other Real Estate Assets Owned (OREO) - Major classifications of OREO (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other real estate	$ 3,387	$ 3,345	$ 4,051
Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other real estate	858	853
Secured by farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other real estate	0	0
Secured by 1-4 family residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other real estate	2,169	1,958
Other real estate loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other real estate	$ 360	$ 534