Reinsurance - Life Insurance Ceded Business (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Reinsurance for Insurance Companies, by Product Segment [Line Items]
Insurance losses and contract holders' benefits	$ 860	$ 854
Life Insurance Segment
Reinsurance for Insurance Companies, by Product Segment [Line Items]
Direct earned premiums	83	77
Ceded earned premiums	(17)	(17)
Earned premiums	66	60
Direct contract holders' benefits incurred	85	76
Ceded contract holders' benefits incurred	(15)	(13)
Insurance losses and contract holders' benefits	$ 70	$ 63

Amount of earned premiums ceded to other entities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.1)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Amount, before premiums ceded to other entities and premiums assumed by the entity, of premiums earned.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Amount, before effect of policies assumed or ceded, of expense related to provision for policy benefits and costs incurred.

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Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred.

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Amount, after premiums ceded to other entities and premiums assumed by the entity, of life premiums earned.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

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