Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total fixed maturity securities, available-for-sale	$ 1,747,404	$ 1,433,626
Equity securities	78,045	80,735
Recurring basis | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities	312
Common stock | Recurring basis
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities	15,165	17,988
Common stock | Recurring basis | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Equity securities	$ 8	$ 43	$ 3,100
Market approach | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Total fixed maturity securities, available-for-sale				$ 4,200