Reinsurance - Life Insurance In-Force and Related Reinsurance (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Insurance [Abstract]
Direct life insurance in-force	$ 117,886,265	$ 110,125,270	$ 102,843,372
Reinsurance risks assumed from other companies	218,020	230,845	257,552
Reinsurance risks ceded to other companies	(24,913,905)	(26,601,422)	(29,646,646)
Net life insurance in-force	$ 93,190,380	$ 83,754,693	$ 73,454,278

Amount of life insurance issued and outstanding assumed from other entity, as disclosed in supplementary reinsurance information. Includes, but is not limited to, dividend and adjustment to face value.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Paragraph Column D
-Subsection 17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 2
-Subparagraph (SX 210.12-17(Column D))
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of life insurance issued and outstanding ceded to other entity, as disclosed in supplementary reinsurance information. Includes, but is not limited to, dividend and adjustment to face value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Paragraph Column C
-Subsection 17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 2
-Subparagraph (SX 210.12-17(Column C))
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

+ Details

Name:	srt_LifeInsuranceInForceCeded
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, before effect of reinsurance, of life insurance issued and outstanding, as disclosed in supplementary reinsurance information. Includes, but is not limited to, dividend and adjustment to face value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Paragraph Column B
-Subsection 17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 2
-Subparagraph (SX 210.12-17(Column B))
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

+ Details

Name:	srt_LifeInsuranceInForceGross
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after effect of reinsurance, of life insurance issued and outstanding, as disclosed in supplementary reinsurance information. Includes, but is not limited to, dividend and adjustment to face value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Paragraph Column E
-Subsection 17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 2
-Subparagraph (SX 210.12-17(Column E))
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

+ Details

Name:	srt_LifeInsuranceInForceNet
Namespace Prefix:	srt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

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