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Reinsurance - Schedule of Unsecured Reinsurance Recoverables from Reinsurers (Detail) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017
Ceded Credit Risk [Line Items]
Amounts recoverable from reinsurers		$ 112,006	$ 90,133
Funds withheld and letters of credit related to the above recoverables		(69,932)
Total unsecured amounts recoverable from reinsurers		42,074
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk
Ceded Credit Risk [Line Items]
Amounts recoverable from reinsurers		112,006
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk | Hannover Reinsurance (Ireland) Limited [Member] | A.M. Best Rating, A+ [Member]
Ceded Credit Risk [Line Items]
Amounts recoverable from reinsurers	[1]	53,609
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk | Allianz Risk Transfer AG (Bermuda) [Member] | A.M. Best Rating, A+ [Member]
Ceded Credit Risk [Line Items]
Amounts recoverable from reinsurers	[1]	13,084
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk | Odyssey America Reinsurance Corporation [Member] | A.M. Best Rating, A [Member]
Ceded Credit Risk [Line Items]
Amounts recoverable from reinsurers		11,754
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk | Minnesota Workers’ Compensation Reinsurance Association [Member]
Ceded Credit Risk [Line Items]
Amounts recoverable from reinsurers	[1]	8,823
Reinsurance Recoverable [Member] | Reinsurer Concentration Risk | Other Reinsurers [Member]
Ceded Credit Risk [Line Items]
Amounts recoverable from reinsurers		$ 24,736
[1] Current participant in our 2019 reinsurance program.

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- Definition

Letters of credit from the reinsurer and Amount of the reinsurer's funds held on its behalf by the ceding insurer, including funds held in trust, under reinsurance treaties or contracts with the assuming insurer as security for the payment of the obligations there under.

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- Definition

Unsecured amounts recoverables from reinsurance net.

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- Definition

Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.(a),6)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=99397103&loc=d3e6824-158387

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=99404803&loc=d3e21409-158489

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