Investments Investments (Other Invested Assets _ Narrative) (Details)	Dec. 31, 2017
Other invested assets
Percentage Estimated Fair Value	80.00%

This percentage represents the net estimated fair value of freestanding derivatives.

No definition available.

Name:	bhl_PercentageEstimatedFairValue
Namespace Prefix:	bhl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant