Basis of Accounting and Consolidation (AOCI) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Total accumulated other comprehensive income, net of tax	$ (8,519)	$ (2,304)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net unrealized gains on securities available-for-sale	(11,418)	(2,619)
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	253	281
Other than Temporary Impairment Loss, Investments, Portion in Other Comprehensive Loss, before Tax, Portion Attributable to Parent, Available-for-sale Securities	(327)	(345)
Unrealized gain (loss) on available-for-sale securities, tax benefit	3,384	841
Total unrealized gain (loss) on available for sale securities, net of tax	(8,287)	(2,059)
Securities with other-than-temporary impairment losses, tax benefit	95	100
Total securities with other-than-temporary impairment losses, net of tax	(232)	(245)
Accumulated other comprehensive income, tax	3,479	941
Total accumulated other comprehensive income, net of tax	$ (8,519)	$ (2,304)