Collateral pledge as security for payments to be received under reinsurance contracts.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of Letters of Credit

+ References

No definition available.

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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

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.

+ References

No definition available.

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- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
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- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

The reporting currency-denominated liability value.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 830
-SubTopic 30
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6897108&loc=SL6897125-166521

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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- Definition

The cash outflow for the settlement of obligation drawn from a contractual arrangement with the lender, including letter of credit, standby letter of credit and revolving credit arrangements, under which borrowings can be made up to a specific amount at any point in time with maturities due beyond one year or the operating cycle, if longer.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
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Other Indebtedness - Additional Information (Detail) £ in Millions		1 Months Ended	12 Months Ended
	Nov. 02, 2018 USD ($)	Nov. 30, 2018	Dec. 31, 2019 USD ($) debt_instrument	Dec. 31, 2018 USD ($)	Dec. 31, 2018 GBP (£)	Mar. 02, 2017 USD ($)
Debt Instrument [Line Items]
Floating rate loan stock denominated in Euros			$ 39,800,000	$ 41,300,000
Amount of collateral under reinsurance agreement			1,184,700,000	944,000,000.0
New Credit Agreement [Member]
Debt Instrument [Line Items]
Line of credit, maximum borrowing amount	$ 325,000,000
Letter of credit facility amount outstanding			$ 70,500,000	$ 500,000
New Credit Agreement [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Variable interest rate of note payable, above 30-day LIBOR			1.25%	1.25%
New Credit Agreement [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Line of credit, maximum borrowing amount	125,000,000
New Credit Agreement [Member] \| Revolving credit facility [Member]
Debt Instrument [Line Items]
Line of credit, maximum borrowing amount	200,000,000
Letter of credit facility amount outstanding			$ 0	$ 0
Prior Agreement [Member]
Debt Instrument [Line Items]
Line of credit, maximum borrowing amount						$ 325,000,000
Prior Agreement [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Repayments of borrowings	$ 125,000,000
Reinsurance Credit Facilities [Member] \| Letter of Credit [Member]
Debt Instrument [Line Items]
Letter of credit facility amount outstanding			$ 139,900,000
Number of letters of credit \| debt_instrument			2
Debt instrument, term			1 year
Amount of collateral under reinsurance agreement			$ 169,900,000
Reinsurance Credit Facilities, Secured Bilateral Line of Credit Facilities [Member] \| Letter of Credit [Member]
Debt Instrument [Line Items]
Letter of credit facility amount outstanding			121,100,000
Reinsurance Credit Facilities, Issued by Banks [Member] \| Letter of Credit [Member]
Debt Instrument [Line Items]
Letter of credit facility amount outstanding			$ 18,800,000
Funds at Lloyd's Instrument [Member] \| Letter of Credit [Member]
Debt Instrument [Line Items]
Letter of credit facility amount outstanding \| £					£ 23.3
Debt instrument, term		1 year
Unsecured Debt [Member]
Debt Instrument [Line Items]
Redemption price, percentage			100.00%
Other Debt - Note Payable [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Variable interest rate of note payable, above 30-day LIBOR			2.00%