Accumulated Other Comprehensive Income - Significant Amounts Reclassified Out of Each Component of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net gain on sale of available-for-sale securities	$ 350	$ 81	$ 350	$ 83
Provision for income taxes	(314)	(287)	(586)	(583)
Net income	1,041	930	1,997	1,732
Amount Reclassified From Accumulated Other Comprehensive Income | Unrealized gains and losses on available-for-sale securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net gain on sale of available-for-sale securities	350	81	350	83
Other than temporary impairment losses	(508)		(508)
Provision for income taxes	54	(28)	54	(28)
Net income	$ (104)	$ 53	$ (104)	$ 55