Investments - Realized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Gain (Loss) on Securities [Line Items]
Realized gain (loss)—investments	$ 1,329	$ 1,951
Realized gains (losses) from investments	(279)	(410)
Realized Gains Losses From Investments Net Of Tax	1,050	1,541
Fixed maturities available for sale [Member]
Gain (Loss) on Securities [Line Items]
Realized gain (loss)—investments	3,670	1,386
Fair value option - change in fair value
Gain (Loss) on Securities [Line Items]
Realized gain (loss)—investments	(2,185)	560
Other Investments [Member]
Gain (Loss) on Securities [Line Items]
Realized gain (loss)—investments	$ (156)	$ 5