Other Comprehensive Income - Summary of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Unrealized gains arising during the period, before U.S. income taxes	$ 6,274	$ 10,531	$ 54,722	$ 54,937
U.S. income taxes	(881)	(690)	(6,441)	(4,045)
Unrealized gains arising during the period, net of U.S. income taxes	5,393	9,841	48,281	50,892
Less reclassification adjustment:
Net realized investment gains	386	436	905	539
U.S. income taxes	(32)	(52)	(57)	(96)
Reclassification adjustment for investment gains realized in net income	354	384	848	443
Other comprehensive income	$ 5,039	$ 9,457	$ 47,433	$ 50,449