REINSURANCE - Additional Information (Detail) $ in Millions	12 Months Ended
Dec. 31, 2017 USD ($) Reinsurer	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Effects of Reinsurance [Line Items]
Reinsurance recoverables included in other long-term assets	$ 824	$ 822
Premiums ceded	969	842	$ 821
Benefits ceded	$ 844	$ 767	$ 666
Number of reinsurers comprising other reinsurance recoverables balance \| Reinsurer	18
Maximum carrying value of reinsurance recoverables for a number of reinsurers	$ 71
Number of reinsurers who have placed cash and securities in trusts \| Reinsurer	3
Cash and securities in trusts held by certain reinsurers	$ 87
100% Coinsurance Agreements
Effects of Reinsurance [Line Items]
Percentage of coinsurance agreement	100.00%
Reinsurance Recoverables \| Reinsurer Concentration Risk
Effects of Reinsurance [Line Items]
Percentage of reinsurance recoverables resulting from 100% coinsurance agreements	33.00%	34.00%

Amount held in cash and securities in trust, at least equal to the recoverable from the reinsurer

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- Definition

Maximum carrying value of reinsurance recoverables for a number of reinsurers

+ References

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- Definition

Number of reinsurers comprising other reinsurance recoverables balance

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Number of reinsurers who have placed cash and securities in trusts

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- Definition

Percentage Of Coinsurance Agreement

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No definition available.

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- Definition

Amount of written premiums ceded to other entities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 605
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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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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.

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Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

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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.

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