Disclosures About Fair Value of Assets and Liabilities - 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	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Available for Sale Securities
Balance at beginning of the period	$ 3,978	$ 5,169
Included in other comprehensive income	(25)	11
Principal payments	13	(1,901)
Ending balance	$ 3,966	$ 3,279