Fair Values of Financial Instruments - Reconciliation of Beginning and Ending Balances of Recurring Fair Value Measurements using Significant Unobservable Level 3 Inputs (Details) - Fair Value, Measurements, Recurring - Available for Sale Securities - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Available for Sale Securities
Beginning Balance	$ 5,932	$ 6,646
Included in other comprehensive income	(223)	199
Principal payments	(540)	(913)
Ending balance	$ 5,169	$ 5,932