Name:	bwp_AverageMarketPriceOfGasAssumed
Namespace Prefix:	bwp_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

The amount of the gas imalance in terms of measure (TBtu) as of the end of the period.

No definition available.

Name:	bwp_GasBalancingVolumeAmountInTbtu
Namespace Prefix:	bwp_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant

Amount of natural gas stored underground as of balance sheet date, in depleted gas reservoirs, aquifers, or salt caverns to meet seasonal and peak load demands, and also as insurance against unforeseen supply disruptions, which is owned by third parties and not recorded on the Company's Condensed Consolidated Balance Sheet.

No definition available.

Name:	bwp_GasHeldForStorageOnBehalfOfCustomers
Namespace Prefix:	bwp_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant

The value of gas balancing asset or liability as of the end of the period

No definition available.

Name:	bwp_GasImbalanceToSubsidiariesAssetLiability
Namespace Prefix:	bwp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	bwp_GasStoredUndergroundAndGasReceivablesAndPayableLineItems
Namespace Prefix:	bwp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The market value of gas held in storage on behalf of its customers. This is not recognized in the financial statements because the Partnership does not own the gas - it is a market risk, however.

No definition available.

Name:	bwp_MarketValueOfGasHeldOnBehalfOfCustomers
Namespace Prefix:	bwp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The market value of natural gas liquids held in storage on behalf of its customers. This is not recognized in the financial statements because the Partnership does not own the natural gas liquids - it is a market risk, however.

No definition available.

Name:	bwp_MarketValueOfNaturalGasLiquidsHeldOnBehalfOfCustomers
Namespace Prefix:	bwp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount of natural gas liquids imbalance in terms of measure (MMbbls) as of the end of the period.

No definition available.

Name:	bwp_NaturalGasLiquidsBalancingVolume
Namespace Prefix:	bwp_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	instant

Amount of natural gas liquids stored underground as of the balance sheet date, in depleted gas reservoirs, aquifers, or salt caverns to meet seasonal and peak load demands, and also as insurance against unforeseen supply disruptions, which is owned by third parties and not recorded on the Company's Condensed Consolidated Balance Sheet.

No definition available.

Name:	bwp_NaturalGasLiquidsHeldForStorageOnBehalfOfCustomers
Namespace Prefix:	bwp_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	instant

The value of Natural Gas Liquids balancing asset or liability as of the end of the period.

No definition available.