Investments (Variable Interest Entities - Narrative) (Details)	Dec. 31, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Material VIEs	0	0

Number of material Variable Interest Entities (VIE) about which the entity is required to make GAAP disclosures.

No definition available.

Name:	bhf_VariableInterestEntityMaterialExistence
Namespace Prefix:	bhf_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant