Transactions with Affiliates (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Effects of Reinsurance [Line Items]
Separate account assets	$ 111,592	$ 109,625
Subsidiaries \| Lombard International Administration Services Company, LLC
Effects of Reinsurance [Line Items]
Separate account assets	42,000
Subsidiaries \| Lombard International Administration Services Company, LLC \| Related Party Transaction, Servicing Fee
Effects of Reinsurance [Line Items]
Related party transaction amount	14
Subsidiaries \| Lombard International Administration Services Company, LLC \| Related Party Transaction, Expense Reimbursements
Effects of Reinsurance [Line Items]
Related party transaction amount	$ 1

Amount of asset at fair value held for benefit of separate account policyholder.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(11))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 80
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=124508989&loc=d3e19393-158473

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 80
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6484091&loc=d3e19268-158472

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 80
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=124505678&loc=SL117422397-158474

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