Regulatory Assets and Liabilities - Narrative (Details)	12 Months Ended
Dec. 31, 2025
Regulatory Assets and Liabilities Disclosure [Abstract]
Period of recovery-minimum (in years)	1 year
Period of recovery-maximum (in years)	18 years

Remaining maximum recovery period of regulatory assets for which no return on investment during recovery period is provided.

No definition available.

Name:	bwp_MaximumPeriodOfRecovery
Namespace Prefix:	bwp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration