Investments (Invested Assets on Deposit, Held In Trust and Pledged as Collateral) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Invested assets on deposit (regulatory deposits)	$ 10,061	$ 9,349
Invested assets held in trust (reinsurance agreements)	5,518	4,561
Invested assets pledged as collateral	5,608	3,641
Total invested assets on deposit, held in trust and pledged as collateral	$ 21,187	$ 17,551

The element presents the invested assets on deposit, held in trust and pledged as collateral.

No definition available.

Name:	bhf_InvestedAssetsOnDepositHeldInTrustAndPledgedAsCollateral
Namespace Prefix:	bhf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Invested assets pledged as collateral.

+ References

No definition available.

+ Details

Name:	bhf_InvestedAssetsPledgedAsCollateral
Namespace Prefix:	bhf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The total amount of cash and securities held by third party trustees pursuant to terms of debt instruments or other agreements as of the date of each statement of financial position presented, which can be used by the trustee only to pay the noncurrent portion of specified obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(b))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

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

- Definition

The carrying amount of the asset transferred to a third party to serve as a deposit, which typically serves as security against failure by the transferor to perform under terms of an agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.8,17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- References

No definition available.

+ Details

Name:	us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration