Reinsurance (Details 4) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($)
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Insurance in Force	$ 117,596,900
Remaining Risk in Force	30,178,131
Remaining Reinsurance in Force	1,705,893
Remaining First Layer Retention	898,649
Radnor Entities
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Reinsurance in Force	1,397,683
Other Reinsurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Reinsurance in Force	308,210
2015 & 2016
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Insurance in Force	25,025,497
Remaining Risk in Force	6,762,026
Remaining Reinsurance in Force	244,105
Remaining First Layer Retention	208,111
2015 & 2016 | Radnor Re 2019-2 Ltd
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Reinsurance in Force	244,105
2015 & 2016 | Other Reinsurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Reinsurance in Force	0
2017
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Insurance in Force	26,279,318
Remaining Risk in Force	6,665,183
Remaining Reinsurance in Force	445,347
Remaining First Layer Retention	221,852
2017 | Radnor Re 2018-1 Ltd.
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Reinsurance in Force	280,180
2017 | Other Reinsurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Reinsurance in Force	165,167
2018
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Insurance in Force	31,375,687
Remaining Risk in Force	7,923,964
Remaining Reinsurance in Force	465,450
Remaining First Layer Retention	253,081
2018 | Radnor Re 2019-1 Ltd.
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Reinsurance in Force	377,509
2018 | Other Reinsurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Reinsurance in Force	87,941
2019
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Insurance in Force	34,916,398
Remaining Risk in Force	8,826,958
Remaining Reinsurance in Force	550,991
Remaining First Layer Retention	215,605
2019 | Radnor Re 2020-1 Ltd.
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Reinsurance in Force	495,889
2019 | Other Reinsurance
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Remaining Reinsurance in Force	$ 55,102