Investments - Fair Value and Gross Unrealized Losses (Details) $ in Thousands	Jun. 30, 2020 USD ($) security	Dec. 31, 2019 USD ($) security
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less	$ 747,886
Fixed maturity securities, Fair Value, More than 12 Months	394,446
Fixed maturity securities, Fair Value, Total	1,142,332
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less	52,554
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months	19,758
Fixed maturity securities, Gross Unrealized Losses, Total	$ 72,312
Number of positions with a gross unrealized loss, 12 Months or Less \| security	594	330
Number of position with a gross unrealized loss, more than 12 months \| security	109	137
Number of position with a gross unrealized loss, Total \| security	703	467
Fair value as a percentage of total fixed maturities and equity securities fair value, 12 Months or Less	12.40%	8.30%
Fair value as a percentage of total fixed maturities and equity securities fair value, more than 12 months	6.60%	8.20%
Fair value as a percentage of total fixed maturities and equity securities fair value, Total	19.00%	16.50%
Mortgage-backed securities
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less	$ 8,344	$ 72,422
Fixed maturity securities, Fair Value, More than 12 Months	933	2,620
Fixed maturity securities, Fair Value, Total	9,277	75,042
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less	130	1,282
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months	81	205
Fixed maturity securities, Gross Unrealized Losses, Total	211	1,487
Other
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less	37	38,341
Fixed maturity securities, Fair Value, More than 12 Months	0	1,527
Fixed maturity securities, Fair Value, Total	37	39,868
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less	0	619
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months	0	2
Fixed maturity securities, Gross Unrealized Losses, Total	0	621
Municipal bonds
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less	81,279	91,195
Fixed maturity securities, Fair Value, More than 12 Months	0	9,160
Fixed maturity securities, Fair Value, Total	81,279	100,355
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less	1,958	977
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months	0	603
Fixed maturity securities, Gross Unrealized Losses, Total	1,958	1,580
Foreign government bonds
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less	0	0
Fixed maturity securities, Fair Value, More than 12 Months	0	0
Fixed maturity securities, Fair Value, Total	0	0
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less	0	0
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months	0	0
Fixed maturity securities, Gross Unrealized Losses, Total	0	0
Corporate bonds
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less	209,868	58,198
Fixed maturity securities, Fair Value, More than 12 Months	6,060	16,622
Fixed maturity securities, Fair Value, Total	215,928	74,820
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less	12,127	886
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months	894	909
Fixed maturity securities, Gross Unrealized Losses, Total	13,021	1,795
Other asset-backed securities
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less	448,358	218,710
Fixed maturity securities, Fair Value, More than 12 Months	387,453	442,791
Fixed maturity securities, Fair Value, Total	835,811	661,501
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less	38,339	1,970
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months	18,783	6,161
Fixed maturity securities, Gross Unrealized Losses, Total	$ 57,122	8,131
Total Fixed Maturity Securities
Fixed maturity securities, Fair Value
Fixed maturity securities, Fair Value, 12 Months or Less		478,866
Fixed maturity securities, Fair Value, More than 12 Months		472,720
Fixed maturity securities, Fair Value, Total		951,586
Fixed maturity securities, Gross Unrealized Losses, 12 Months or Less		5,734
Fixed maturity securities, Gross Unrealized Losses, More than 12 Months		7,880
Fixed maturity securities, Gross Unrealized Losses, Total		$ 13,614

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