Ceded Reinsurance - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Effects of Reinsurance [Line Items]
Policyholders' surplus for reinsurance	$ 500,000
Reinsurance rating description	A reinsurer generally must have a rating from A.M. Best and/or S&P of “A” or better, or an equivalent financial strength if not rated, plus at least $500 million in policyholders’ surplus to meet our standards of acceptability.
Reserve for uncollectible reinsurance amount	$ 6,900	$ 11,300
Collateral Held	159,570
Ceded Balances Payable
Effects of Reinsurance [Line Items]
Collateral Held	107,400
Letter of Credit
Effects of Reinsurance [Line Items]
Collateral Held	45,800
All Other
Effects of Reinsurance [Line Items]
Collateral Held	$ 6,400

Reinsurers rating.

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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

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Amount of funds held as security for payments to be received under reinsurance contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.13(c))
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Amount of policyholders' surplus excluded from calculating deferred taxes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(c)
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- Definition

Amount of valuation allowance for reinsurance recoverables. 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

No definition available.

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