Investments - Schedule of Rollforward of Mortgagees Allowance for Credit Loss (Details) - USD ($)	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	$ 133,000,000	$ 121,000,000
Charge offs, net of recoveries	(5,000,000)	(6,000,000)
Reductions for mortgages disposed	0	0
Additions from purchase of PCD mortgage loans	0	0
Provision (release)	31,000,000	15,000,000
Ending Balance	159,000,000	130,000,000
Financing receivables, accrued interest receivable	48,000,000	42,000,000
Accrued interest written off	0	0
Apartment
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	32,000,000	23,000,000
Charge offs, net of recoveries	(1,000,000)	0
Reductions for mortgages disposed	0	0
Additions from purchase of PCD mortgage loans	0	0
Provision (release)	(8,000,000)	5,000,000
Ending Balance	23,000,000	28,000,000
Hotel
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	11,000,000	7,000,000
Charge offs, net of recoveries	0	0
Reductions for mortgages disposed	0	0
Additions from purchase of PCD mortgage loans	0	0
Provision (release)	(7,000,000)	0
Ending Balance	4,000,000	7,000,000
Office
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	28,000,000	44,000,000
Charge offs, net of recoveries	(4,000,000)	(6,000,000)
Reductions for mortgages disposed	0	0
Additions from purchase of PCD mortgage loans	0	0
Provision (release)	32,000,000	2,000,000
Ending Balance	56,000,000	40,000,000
Retail
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	17,000,000	19,000,000
Charge offs, net of recoveries	0	0
Reductions for mortgages disposed	0	0
Additions from purchase of PCD mortgage loans	0	0
Provision (release)	13,000,000	0
Ending Balance	30,000,000	19,000,000
Warehouse
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	27,000,000	20,000,000
Charge offs, net of recoveries	0	0
Reductions for mortgages disposed	0	0
Additions from purchase of PCD mortgage loans	0	0
Provision (release)	(4,000,000)	0
Ending Balance	23,000,000	20,000,000
Other
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	2,000,000	3,000,000
Charge offs, net of recoveries	0	0
Reductions for mortgages disposed	0	0
Additions from purchase of PCD mortgage loans	0	0
Provision (release)	(1,000,000)	(1,000,000)
Ending Balance	1,000,000	2,000,000
Residential Mortgage
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	16,000,000	5,000,000
Charge offs, net of recoveries	0	0
Reductions for mortgages disposed	0	0
Additions from purchase of PCD mortgage loans	0	0
Provision (release)	6,000,000	9,000,000
Ending Balance	$ 22,000,000	$ 14,000,000

Financing Receivable, 90 Days or More Past Due, Still Accruing, Writeoff

No definition available.

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Namespace Prefix:	jxn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, after allowance for credit loss, of accrued interest on financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-5

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3A
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-3A

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase in allowance for credit loss on financing receivable purchased with credit deterioration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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- Definition

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from sale of loan. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, excluding accrued interest, of decrease (increase) in allowance for credit loss on financing receivable from writeoff (recovery). Excludes net investment in lease.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476148/220-40-50-22

+ Details

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- Details

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