Other Comprehensive Income (Loss) - Summary of Available for Sale Securities Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 181,321	$ 172,521
Other comprehensive income (loss)	(2,933)	60
Ending balance	181,372	174,853
Accumulated Net Investment Gain (Loss) Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2,901)	(935)
Unrealized gains (losses) arising during the period	(4,052)	5
Reclassification of realized gains during the period	(136)	(3)
Related deferred taxes (at a Federal Income Tax rate of 21% for March 31, 2018 and 35% for March 31, 2017)	879	(1)
Other comprehensive income (loss)	(3,309)	1
Ending balance	$ (6,210)	$ (934)