Schedule II. Condensed Financial Information Of Registrant - Balance Sheets Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Condensed Financial Statements, Captions [Line Items]
Fixed maturity investments trading, amortized cost	$ 15,038,551	$ 13,552,579
Short-term investments, amortized cost	$ 4,671,581	$ 5,298,385
Preference shares, par value (in usd per share)	$ 1.00	$ 1.00
Preference shares, shares issued (in shares)	30,000	30,000
Preference shares, shares outstanding (in shares)	30,000	30,000
Common shares, par value (in usd per share)	$ 1.00	$ 1.00
Common shares, shares issued (in shares)	43,717,836	44,444,831
Common shares, shares outstanding (in shares)	43,717,836	44,444,831
Parent Company
Condensed Financial Statements, Captions [Line Items]
Fixed maturity investments trading, amortized cost	$ 176,084	$ 0
Short-term investments, amortized cost	$ 61,747	$ 46,503
Preference shares, par value (in usd per share)	$ 1.00	$ 1.00
Preference shares, shares issued (in shares)	30,000	30,000
Preference shares, shares outstanding (in shares)	30,000	30,000
Common shares, par value (in usd per share)	$ 1.00	$ 1.00
Common shares, shares issued (in shares)	43,717,836	44,444,831
Common shares, shares outstanding (in shares)	43,717,836	44,444,831