Reinsurance Ceded - Additional Information (Detail) - Reinsurance Segment	9 Months Ended
Sep. 30, 2020
Effects Of Reinsurance [Line Items]
Retrocession protection term	1 year
Term of catastrophe bonds	4 years

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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Period Type:	duration