Reinsurance - Prepaid Reinsurance Premiums and Reinsurance Recoverable and Receivable (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Reinsurance Disclosures [Abstract]
Prepaid reinsurance premiums	$ 70,113	$ 175,208
Reinsurance recoverable on paid losses and LAE	42,333	70,015
Reinsurance recoverable on unpaid losses and LAE	66,158	123,221	$ 269,071	$ 393,365
Reinsurance recoverable	$ 108,491	$ 193,236

The unexpired portion of premiums ceded on policies in force as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 340
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6485982&loc=d3e22818-158507

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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- References

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- Definition

Amount, after valuation allowance, recoverable under reinsurance contracts for losses reported to the ceding insurer but not yet paid and amounts expected for incurred losses and settlement expenses, which have not yet been reported to the ceding insurer.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=99404803&loc=d3e21412-158489

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
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Amount, after valuation allowance, recoverable under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, policy benefits and policy reserves. Excludes premiums paid under reinsurance contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=99404803&loc=d3e21412-158489

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- Definition

Amount, after valuation allowance, recoverable under reinsurance contracts for losses reported to and paid by the ceding insurer.

+ References

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