Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized gains (losses) arising during the period, before income taxes	$ 4,166			$ (2,472)			$ 21,362	$ (9,665)
Income taxes	(875)			519			(4,486)	2,030
Unrealized gains (losses) arising during the period, net of income tax	3,291			(1,953)			16,876	(7,635)
Less reclassification adjustment [Abstract]
Net realized investment gains on fixed-maturity securities, before income taxes	61			0			378	240
Income taxes	(12)			0			(79)	(50)
Reclassification adjustment included in net income, net of income taxes	49			0			299	190
Other comprehensive income (loss)	$ 3,242	$ 6,555	$ 6,780	$ (1,953)	$ (1,016)	$ (4,856)	$ 16,577	$ (7,825)