Investments - Schedule of Net Realized Investment Gains and Losses Recognized in Net Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Realized Investment Gains Losses [Abstract]
Gross gains from sales of available-for-sale securities	$ 765	$ 357
Gross losses from sales of available-for-sale securities	(143)	(66)
Credit losses on available-for-sale securities	(154)	(3,701)
Net gains (losses) recognized in net income during the period on equity securities	1,424	(6,672)
Gains (losses) from bifurcated options	(17)	52
Gains (losses) on trading securities	(109)
Net realized investment gains (losses)	$ 1,766	$ (10,030)