Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance beginning	$ 142,944	$ 140,108	$ 140,108
Before reclassifications	1,974		(2,141)
Reclassifications	(143)		(712)
Balance ending	149,713	146,906	142,944
Total [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance beginning	(2,617)	236	236
Balance ending	(786)	3,522	(2,617)
Unrealized Gains and Losses on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance beginning	(2,633)	469	469
Before reclassifications	1,974		(2,390)
Reclassifications	(143)		(712)
Balance ending	(802)		(2,633)
Changes in Pension Plan Assets and Benefit Obligations [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance beginning	16	$ (233)	(233)
Before reclassifications	0		249
Reclassifications	0		0
Balance ending	$ 16		$ 16