Investments - AFS Allowance for Credit Losses (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, December 31, 2019	$ 0
Increase (decrease)	(605)
Balance, December 31, 2020	186
Corporate Bond Securities [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, December 31, 2019	0
Increase (decrease)	(517)
Balance, December 31, 2020	148
Redeemable preferred stock [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, December 31, 2019	0
Increase (decrease)	(88)
Balance, December 31, 2020	38
Cumulative Effect, Period of Adoption, Adjustment [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, December 31, 2019	791
Cumulative Effect, Period of Adoption, Adjustment [Member] | Corporate Bond Securities [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, December 31, 2019	665
Cumulative Effect, Period of Adoption, Adjustment [Member] | Redeemable preferred stock [Member]
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, December 31, 2019	$ 126