Investments - Schedule of Net Realized Investment Gains and Losses Recognized in Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Realized Investment Gains Losses [Abstract]
Gross gains from sales of available-for-sale securities	$ 827	$ 293	$ 1,183	$ 471
Gross losses from sales of available-for-sale securities	(51)	(42)	(116)	(285)
Credit losses on available-for-sale securities	(545)	(161)	(4,246)	(161)
Net gains (losses) recognized in net income during the period on equity securities	1,547	977	(5,125)	3,878
Gains (losses) from bifurcated options	(36)		16
Gains (losses) on trading securities				11
Net realized investment gains (losses)	$ 1,742	$ 1,067	$ (8,288)	$ 3,914