Commitments and Contingencies Narrative Data (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Outstanding balance of loans sold through the MPF program	$ 452,000	$ 422,300
Credit Enhancement Obligation [Member]
Loss Contingencies [Line Items]
Contractual risk sharing commitments, maximum liability	634	595
Reserve for contingent contractual liability, amount accrued	24	$ 23
Federal Home Loan Bank MPF Program [Member]
Loss Contingencies [Line Items]
Total loans sold through the MPF program since inceptions into the program	26,900
Outstanding balance of loans sold through the MPF program	$ 16,000