Transactions With Related Parties	9 Months Ended
	Sep. 30, 2023
Related Party Transactions [Abstract]
Transactions with related parties	Premia Reinsurance Ltd. is a multi-line Bermuda reinsurance company (and its affiliates together with Premia Holdings Ltd., “Premia”). The Company has entered into certain reinsurance transactions with Premia. For the nine months ended September 30, 2023, the Company recorded net premiums written and earned of approximately $80 million, compared to a de minimis amount for the nine months ended September 30, 2022. At September 30, 2023, the Company recorded a funds held asset from Premia of $176 million, compared to $119 million at December 31, 2022.Somers Group Holdings Ltd. and its wholly owned subsidiaries (collectively, “Somers”) are wholly owned by Greysbridge. The Company has entered into certain reinsurance transactions with Somers. For the nine months ended September 30, 2023, the Company’s net premiums written was reduced by $457 million, compared to $552 million for the nine months ended September 30, 2022. In addition, Somers paid certain acquisition costs and administrative fees to the Company. At September 30, 2023, the Company recorded a reinsurance recoverable on unpaid and paid losses from Somers of $1.3 billion and a reinsurance balance payable to Somers of $499 million, compared to $1.2 billion and $414 million, respectively, at December 31, 2022.