Investments	6 Months Ended
Jun. 30, 2013
Investments [Abstract]
Consolidation, Variable Interest Entity, Policy [Policy Text Block]	Note 2: Investments Bluegrass Project In the second quarter 2013, the Partnership executed an agreement with the Williams Companies, Inc (Williams) to continue the development process for the Bluegrass Project - a project that would transport NGLs from the Marcellus and Utica shale plays to the petrochemical and export complex in the U.S. Gulf Coast region, and related fractionation and storage facilities. The proposed project would include constructing a new pipeline, a new large-scale fractionation plant and related liquids storage and transport facilities (collectively, the Bluegrass Project). In connection with the Bluegrass Project, the Partnership executed agreements with BPHC to form Boardwalk Bluegrass Pipeline, LLC (Boardwalk Bluegrass) and Boardwalk Moss Lake, LLC (Boardwalk Moss Lake). Boardwalk Bluegrass and Boardwalk Moss Lake, together with affiliates of Williams, formed Bluegrass Pipeline Company LLC (Bluegrass Pipeline) and Moss Lake Fractionation LLC (Moss Lake) to pursue and, if approved, develop, own and construct the pipeline and fractionation facilities. Boardwalk Bluegrass and Boardwalk Moss Lake currently own 50% of the equity ownership interests in Bluegrass Pipeline and Moss Lake, respectively, with affiliates of Williams owning the other 50%. The parties have equal voting and participation rights. Boardwalk Bluegrass and Boardwalk Moss Lake The Partnership contributed a total of $10.0 million for initial equity ownership interests of 59% and 61% in Boardwalk Bluegrass and Boardwalk Moss Lake, respectively, with BPHC owning the remaining equity ownership interests. BPHC has agreed to contribute up to an aggregate of $100.0 million to these entities to fund certain agreed upon pre-construction development costs, with BPHC contributing all additional required capital until such time as BPHC has a 90% equity ownership interest in each entity. Additional capital required for Boardwalk Bluegrass and Boardwalk Moss Lake to continue to pursue the Bluegrass Project is subject to approval by the Partnership and BPHC. As of June 30, 2013, the Partnership held equity ownership interests of 26% and 61%, respectively, in Boardwalk Bluegrass and Boardwalk Moss Lake. The Partnership determined that Boardwalk Bluegrass and Boardwalk Moss Lake were VIEs due to disproportionate voting rights held by BPHC. The Partnership is the primary beneficiary of Boardwalk Bluegrass and Boardwalk Moss Lake because the Partnership has the power to direct the significant activities related to each entity's investment decision in Bluegrass Pipeline and Moss Lake. The financial information of Boardwalk Bluegrass and Boardwalk Moss Lake is measured at historical carrying amounts in accordance with the accounting requirements applicable to transactions between entities under common control. At June 30, 2013, the Partnership included in its Condensed Consolidated Balance Sheet cash of $4.8 million and investments in unconsolidated affiliates of $25.0 million that represent amounts recorded by Boardwalk Bluegrass and Boardwalk Moss Lake. Bluegrass Pipeline and Moss Lake Bluegrass Pipeline and Moss Lake were determined to be VIEs, because the entities will require additional funding from each equity owner throughout the development and construction phases of the Bluegrass Project. Boardwalk Bluegrass and Boardwalk Moss Lake are not the primary beneficiaries of Bluegrass Pipeline or Moss Lake, because the power to direct the activities that most significantly impact the entity's economic performance is shared between the equity owners. As a result, Boardwalk Bluegrass and Boardwalk Moss Lake account for the investments in Bluegrass Pipeline and Moss Lake under the equity method of accounting. Boardwalk Bluegrass' and Boardwalk Moss Lake's maximum exposure to loss is limited to the carrying value of its investments in Bluegrass Pipeline and Moss Lake, which was $25.0 million as of June 30, 2013. The Partnership's maximum exposure to loss is limited to the amount of the capital contributions it has made to Boardwalk Bluegrass and Boardwalk Moss Lake, or $10.0 million, as of June 30, 2013.

Note 2: Investments

Bluegrass Project

In the second quarter 2013, the Partnership executed an agreement with the Williams Companies, Inc (Williams) to continue the development process for the Bluegrass Project - a project that would transport NGLs from the Marcellus and Utica shale plays to the petrochemical and export complex in the U.S. Gulf Coast region, and related fractionation and storage facilities. The proposed project would include constructing a new pipeline, a new large-scale fractionation plant and related liquids storage and transport facilities (collectively, the Bluegrass Project).

In connection with the Bluegrass Project, the Partnership executed agreements with BPHC to form Boardwalk Bluegrass Pipeline, LLC (Boardwalk Bluegrass) and Boardwalk Moss Lake, LLC (Boardwalk Moss Lake). Boardwalk Bluegrass and Boardwalk Moss Lake, together with affiliates of Williams, formed Bluegrass Pipeline Company LLC (Bluegrass Pipeline) and Moss Lake Fractionation LLC (Moss Lake) to pursue and, if approved, develop, own and construct the pipeline and fractionation facilities. Boardwalk Bluegrass and Boardwalk Moss Lake currently own 50% of the equity ownership interests in Bluegrass Pipeline and Moss Lake, respectively, with affiliates of Williams owning the other 50%. The parties have equal voting and participation rights.

Boardwalk Bluegrass and Boardwalk Moss Lake

The Partnership contributed a total of $10.0 million for initial equity ownership interests of 59% and 61% in Boardwalk Bluegrass and Boardwalk Moss Lake, respectively, with BPHC owning the remaining equity ownership interests. BPHC has agreed to contribute up to an aggregate of $100.0 million to these entities to fund certain agreed upon pre-construction development costs, with BPHC contributing all additional required capital until such time as BPHC has a 90% equity ownership interest in each entity. Additional capital required for Boardwalk Bluegrass and Boardwalk Moss Lake to continue to pursue the Bluegrass Project is subject to approval by the Partnership and BPHC. As of June 30, 2013, the Partnership held equity ownership interests of 26% and 61%, respectively, in Boardwalk Bluegrass and Boardwalk Moss Lake.

The Partnership determined that Boardwalk Bluegrass and Boardwalk Moss Lake were VIEs due to disproportionate voting rights held by BPHC. The Partnership is the primary beneficiary of Boardwalk Bluegrass and Boardwalk Moss Lake because the Partnership has the power to direct the significant activities related to each entity's investment decision in Bluegrass Pipeline and Moss Lake.

The financial information of Boardwalk Bluegrass and Boardwalk Moss Lake is measured at historical carrying amounts in accordance with the accounting requirements applicable to transactions between entities under common control. At June 30, 2013, the Partnership included in its Condensed Consolidated Balance Sheet cash of $4.8 million and investments in unconsolidated affiliates of $25.0 million that represent amounts recorded by Boardwalk Bluegrass and Boardwalk Moss Lake.

Bluegrass Pipeline and Moss Lake

Bluegrass Pipeline and Moss Lake were determined to be VIEs, because the entities will require additional funding from each equity owner throughout the development and construction phases of the Bluegrass Project. Boardwalk Bluegrass and Boardwalk Moss Lake are not the primary beneficiaries of Bluegrass Pipeline or Moss Lake, because the power to direct the activities that most significantly impact the entity's economic performance is shared between the equity owners. As a result, Boardwalk Bluegrass and Boardwalk Moss Lake account for the investments in Bluegrass Pipeline and Moss Lake under the equity method of accounting. Boardwalk Bluegrass' and Boardwalk Moss Lake's maximum exposure to loss is limited to the carrying value of its investments in Bluegrass Pipeline and Moss Lake, which was $25.0 million as of June 30, 2013. The Partnership's maximum exposure to loss is limited to the amount of the capital contributions it has made to Boardwalk Bluegrass and Boardwalk Moss Lake, or $10.0 million, as of June 30, 2013.