Reinsurance and Indemnification - 2017-1 Excess Catastrophe Reinsurance Contract (Details) $ in Millions	9 Months Ended	12 Months Ended
Dec. 31, 2017 USD ($)	Dec. 31, 2019 USD ($) state
Ceded Credit Risk [Line Items]
Limit of aggregate losses under aggregate excess agreement		$ 3,400
2017-1 Excess Catastrophe Reinsurance Contract
Ceded Credit Risk [Line Items]
Number of states covered by reinsurance agreement \| state		49
Limit of aggregate losses under aggregate excess agreement	$ 375	$ 3,400
Catastrophe reinsurance aggregate loss limit		$ 3,690
Co-participation percentage		5.00%
Gap Fill Excess Catastrophe Reinsurance Contract
Ceded Credit Risk [Line Items]
Limit of aggregate losses under aggregate excess agreement		$ 219
Retention percentage of reinsurance limit		100.00%
Catastrophe reinsurance aggregate loss limit		$ 4,130
Gap Fill Excess Catastrophe Reinsurance Contract, Layers
Ceded Credit Risk [Line Items]
Limit of aggregate losses under aggregate excess agreement		$ 1,610
Co-participation percentage		5.00%
Minimum \| 2017-1 Excess Catastrophe Reinsurance Contract
Ceded Credit Risk [Line Items]
Retention amount for catastrophe reinsurance agreement contracts		$ 2,750
Minimum \| Gap Fill Excess Catastrophe Reinsurance Contract
Ceded Credit Risk [Line Items]
Retention amount for catastrophe reinsurance agreement contracts		2,750
Minimum \| Gap Fill Excess Catastrophe Reinsurance Contract, Layers
Ceded Credit Risk [Line Items]
Retention amount for catastrophe reinsurance agreement contracts		$ 2,750

- Definition

Represents the retention percentage of annual coverage limit provided by the insurance arrangement for catastrophe claims.

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No definition available.

+ Details

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- Definition

The limit of aggregated losses per contract year beyond which coverage provided by an aggregate excess agreement applies.

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No definition available.

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- Definition

Catastrophe Reinsurance Aggregate Loss Limit Per Contract Year, In Excess of Layers

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No definition available.

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- Definition

Catastrophe Reinsurance Agreement Contracts, Co-participation Percentage

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No definition available.

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- Definition

Represents the retention amount of catastrophe reinsurance agreement contracts.

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No definition available.

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- Definition

Represents the number of states covered under the reinsurance agreement.

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No definition available.

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- Definition

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.

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No definition available.

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