Collateralized Reinsurance And Trust Agreements (Summary of Collateralized Reinsurance Agreements) (Details) - Kilimanjaro Re Limited [Member] $ in Thousands	6 Months Ended
	Jun. 30, 2021 USD ($)
Effects of Reinsurance [Line Items]
Limit	$ 2,325,000
Series 2017-1 Class A-2 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 13, 2017
Reinsurance agreements expiration date	Apr. 13, 2022
Limit	$ 50,000
Series 2017-1 Class B-2 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 13, 2017
Reinsurance agreements expiration date	Apr. 13, 2022
Limit	$ 75,000
Series 2017-1 Class C-2 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 13, 2017
Reinsurance agreements expiration date	Apr. 13, 2022
Limit	$ 175,000
Series 2018-1 Class A-1 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 30, 2018
Reinsurance agreements expiration date	May 06, 2022
Limit	$ 62,500
Series 2018-1 Class B-1 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 30, 2018
Reinsurance agreements expiration date	May 06, 2022
Limit	$ 200,000
Series 2018-1 Class A-2 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 30, 2018
Reinsurance agreements expiration date	May 05, 2023
Limit	$ 62,500
Series 2018-1 Class B-2 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 30, 2018
Reinsurance agreements expiration date	May 05, 2023
Limit	$ 200,000
Series 2020-1 Class A-2 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Dec. 12, 2019
Reinsurance agreements expiration date	Dec. 19, 2023
Limit	$ 150,000
Series 2020-1 Class B-2 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Dec. 12, 2019
Reinsurance agreements expiration date	Dec. 19, 2023
Limit	$ 275,000
Series 2019-1 Class A-1 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Dec. 12, 2019
Reinsurance agreements expiration date	Dec. 19, 2024
Limit	$ 150,000
Series 2019-1 Class B-1 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Dec. 12, 2019
Reinsurance agreements expiration date	Dec. 19, 2024
Limit	$ 275,000
Series 2019-1 Class A-2 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 08, 2021
Reinsurance agreements expiration date	Apr. 21, 2025
Limit	$ 150,000
Series 2019-1 Class B-2 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 08, 2021
Reinsurance agreements expiration date	Apr. 21, 2025
Limit	$ 85,000
Series 2020-1 Class A-1 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 08, 2021
Reinsurance agreements expiration date	Apr. 21, 2025
Limit	$ 85,000
Series 2020-1 Class B-1 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 08, 2021
Reinsurance agreements expiration date	Apr. 20, 2026
Limit	$ 150,000
Series 2020-1 Class C-1 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 08, 2021
Reinsurance agreements expiration date	Apr. 20, 2026
Limit	$ 90,000
Series 2020-1 Class C-2 [Member]
Effects of Reinsurance [Line Items]
Effective Date	Apr. 08, 2021
Reinsurance agreements expiration date	Apr. 20, 2026
Limit	$ 90,000