Boardwalk Pipeline Partners (BWP) 10-Q3 Aug 152015 Q2 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2015	Aug. 03, 2015
Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Trading Symbol	BWP
Entity Registrant Name	Boardwalk Pipeline Partners, LP
Entity Central Index Key	1,336,047
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		250,296,782

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Current Assets:
Cash and cash equivalents	$ 19.3	$ 6.6
Receivables:
Trade	93.8	102.6
Other	11.8	8.3
Gas transportation receivables	6.3	9.1
Gas and liquids stored underground	8.5	4.1
Prepayments	19.8	14.5
Other current assets	2.6	4.4
Total current assets	162.1	149.6
Property, Plant and Equipment:
Natural gas transmission and other plant	9,363.4	9,250.1
Construction work in progress	135.2	105.5
Property, plant and equipment, gross	9,498.6	9,355.6
Less—accumulated depreciation and amortization	1,923.6	1,766.4
Property, plant and equipment, net	7,575	7,589.2
Other Assets:
Goodwill	237.4	237.4
Gas stored underground	97.9	86.4
Other	143.8	144.2
Total other assets	479.1	468
Total Assets	8,216.2	8,206.8
Payables:
Trade, net	64.6	51.7
Affiliates	0.9	1.5
Other	21.4	10.4
Gas payables	10.9	8.5
Accrued taxes, other	47.5	47.1
Accrued interest	39.6	47.4
Accrued payroll and employee benefits	15.9	26.3
Deferred income	4.4	1.9
Other current liabilities	34	25.4
Total current liabilities	239.2	220.2
Long-term debt and capital lease obligation	3,493.6	3,689.7
Other Liabilities and Deferred Credits:
Pension liability	18.9	19.2
Asset retirement obligation	40.5	39.9
Provision for other asset retirement	62	60.5
Payable to affiliate	16	16
Other	63.7	59
Total other liabilities and deferred credits	$ 201.1	$ 194.6
Commitments and Contingencies
Partners’ Capital:
Common units – 250.3 million units and 243.3 million units issued and outstanding as of June 30, 2015, and December 31, 2014	$ 4,274.5	$ 4,095.1
General partner	83.7	80
Accumulated other comprehensive loss	(75.9)	(72.8)
Total partners’ capital	4,282.3	4,102.3
Total Liabilities and Partners' Capital	$ 8,216.2	$ 8,206.8

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - shares shares in Millions	Jun. 30, 2015	Dec. 31, 2014
Common units issued	250.3	243.3
Common units outstanding	250.3	243.3

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating Revenues:
Transportation	$ 256.9	$ 245.7	$ 546.5	$ 550
Parking and lending	2.8	9.2	5.6	18.4
Storage	20.9	22.1	40.2	50.9
Other	18	16.4	36	31
Total operating revenues	298.6	293.4	628.3	650.3
Operating Costs and Expenses:
Fuel and transportation	23.6	29.9	50.6	62.9
Operation and maintenance	54.6	43.9	97	86.6
Administrative and general	31.8	30.5	62.4	57.3
Depreciation and amortization	81	69.6	162.6	138.8
Asset impairment	0	1.4	0.1	8.6
Net gain on sale of operating assets	(0.1)	(0.8)	(0.1)	(1.2)
Taxes other than income taxes	21.8	22.4	47	48.2
Total operating costs and expenses	212.7	196.9	419.6	401.2
Operating income	85.9	96.5	208.7	249.1
Other Deductions (Income):
Interest expense	45.9	40.2	91.1	81.1
Interest income	(0.1)	(0.2)	(0.2)	(0.3)
Equity losses in unconsolidated affiliates	0	0.5	0	86.6
Miscellaneous other income, net	(0.4)	0	(0.6)	(0.1)
Total other deductions	45.4	40.5	90.3	167.3
Income before income taxes	40.5	56	118.4	81.8
Income taxes	0.1	0.1	0.3	0.3
Net income	40.4	55.9	118.1	81.5
Net loss attributable to noncontrolling interests	0	(1.5)	0	(86.1)
Net income attributable to controlling interests	$ 40.4	$ 57.4	$ 118.1	$ 167.6

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF INCOME Net Income Per Unit: - Common Units - $ / shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net income per unit:
Net income per common unit (in units)	$ 0.16	$ 0.23	$ 0.47	$ 0.68
Weighted-average number of units outstanding:
Weighted-average number of units outstanding (in units)	250.3	243.3	247.3	243.3
Net Income per Unit:
Cash distribution declared and paid to common units (in units)	$ 0.10	$ 0.10	$ 0.20	$ 0.20

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net Income	$ 40.4	$ 55.9	$ 118.1	$ 81.5
Other comprehensive income (loss):
Loss on cash flow hedges	0	0	0	(0.9)
Reclassification adjustment transferred to Net Income from cash flow hedges	0.6	0.7	1.2	1.6
Pension and other postretirement benefit costs	(2.2)	(2)	(4.3)	(3.9)
Total Comprehensive Income	38.8	54.6	115	78.3
Comprehensive loss attributable to noncontrolling interests	0	(1.5)	0	(86.1)
Comprehensive income attributable to controlling interests	$ 38.8	$ 56.1	$ 115	$ 164.4

CONDENSED CONSOLIDATED STATEME7

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating Activities:
Net Income	$ 118.1	$ 81.5
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	162.6	138.8
Amortization of deferred costs	5.2	2.9
Asset impairment	0.1	8.6
Net gain on sale of operating assets	(0.1)	(1.2)
Equity losses in unconsolidated affiliates	0	86.6
Changes in operating assets and liabilities:
Trade and other receivables	5.3	19.2
Other receivables, affiliates	0	0.9
Gas receivables and storage assets	(13.1)	(8.5)
Costs recoverable from customers	1.9	1
Other assets	(1.8)	(3.8)
Trade and other payables	9.9	(11.6)
Other payables, affiliates	(0.7)	(0.5)
Gas payables	2.4	7.4
Accrued liabilities	(16.5)	(6.9)
Other liabilities	12.2	(6.3)
Net cash provided by operating activities	285.5	308.1
Investing Activities:
Capital expenditures	(136.3)	(162.7)
Proceeds from sale of operating assets	0.1	2.9
Advances to affiliates	0	0.1
Investment in unconsolidated affiliates	0	(20.3)
Distributions from unconsolidated affiliates	0	10.7
Net cash used in investing activities	(136.2)	(169.3)
Financing Activities:
Proceeds from long-term debt	247.1	0
Repayment of borrowings from long-term debt and term loan	(725)	0
Proceeds from borrowings on revolving credit agreement	835	220
Repayment of borrowings on revolving credit agreement, including financing fees	(558.6)	(295)
Principal payment of capital lease obligation	(0.2)	(0.2)
Advances from affiliate	0.1	0.1
Distributions paid	(50.4)	(49.6)
Proceeds from sale of common units	113.1	0
Capital contributions from general partner	2.3	0
Capital contributions from noncontrolling interests	0	7.8
Distributions paid to noncontrolling interests	0	(7.1)
Net cash used in financing activities	(136.6)	(124)
Increase in cash and cash equivalents	12.7	14.8
Cash and cash equivalents at beginning of period	6.6	28.5
Cash and cash equivalents at end of period	$ 19.3	$ 43.3

CONDENSED CONSOLIDATED STATEME8

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Unaudited) - USD ($) $ in Millions	Total	Accumulated Other Comprehensive Loss	Noncontrolling Interest	Limited PartnerCommon Units	General Partner
Beg Partners' Capital at Dec. 31, 2013	$ 4,063.4	$ (63.8)	$ 86.5	$ 3,963.4	$ 77.3
Add (deduct):
Net income (loss)	81.5	0	(86.1)	164.2	3.4
Distributions paid	(49.6)	0	0	(48.6)	(1)
Capital contributions from noncontrolling interests	7.8	0	7.8	0	0
Distributions paid to noncontrolling interests	(7.1)	0	(7.1)	0	0
Other comprehensive loss	(3.2)	(3.2)	0	0	0
End Partners' Capital at Jun. 30, 2014	4,092.8	(67)	1.1	4,079	79.7
Beg Partners' Capital at Dec. 31, 2014	4,102.3	(72.8)	0	4,095.1	80
Add (deduct):
Net income (loss)	118.1	0	0	115.7	2.4
Distributions paid	(50.4)	0	0	(49.4)	(1)
Sale of common units net of related transaction costs	113.1	0	0	113.1	0
Capital contribution from general partner	2.3	0	0	0	2.3
Other comprehensive loss	(3.1)	(3.1)	0	0	0
End Partners' Capital at Jun. 30, 2015	$ 4,282.3	$ (75.9)	$ 0	$ 4,274.5	$ 83.7

Basis of Presentation

Basis of Presentation	6 Months Ended
Basis of Presentation	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation [Text Block]	Note 1: Basis of Presentation Boardwalk Pipeline Partners, LP (the Partnership) is a Delaware limited partnership formed in 2005 to own and operate the business conducted by its primary subsidiary Boardwalk Pipelines, LP (Boardwalk Pipelines) and its operating subsidiaries and consists of integrated natural gas and natural gas liquids (NGLs) pipeline and storage systems and natural gas gathering and processing. As of August 3, 2015 , Boardwalk Pipelines Holding Corp. (BPHC), a wholly-owned subsidiary of Loews Corporation (Loews), owned 125.6 million of the Partnership’s common units, and, through Boardwalk GP, LP (Boardwalk GP), an indirect wholly-owned subsidiary of BPHC, holds the 2% general partner interest and all of the incentive distribution rights (IDRs). As of August 3, 2015 , the common units and general partner interest owned by BPHC represent approximately 51% of the Partnership’s equity interests, excluding the IDRs. The Partnership’s common units are traded under the symbol “BWP” on the New York Stock Exchange (NYSE). The accompanying unaudited condensed consolidated financial statements of the Partnership were prepared pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, the accompanying condensed consolidated financial statements reflect all adjustments (consisting of only normal recurring accruals) necessary to present fairly the financial position as of June 30, 2015 , and December 31, 2014 , and the results of operations and comprehensive income for the three and six months ended June 30, 2015 and 2014 , and changes in cash flows and changes in equity for the six months ended June 30, 2015 and 2014 . Reference is made to the Notes to Consolidated Financial Statements in the Annual Report on Form 10-K for the year ended December 31, 2014 ( 2014 Annual Report on Form 10-K), which should be read in conjunction with these unaudited condensed consolidated financial statements. The accounting policies described in Note 2 to the Consolidated Financial Statements included in such 2014 Annual Report on Form 10-K are the same used in preparing the accompanying unaudited condensed consolidated financial statements. Net income for interim periods may not necessarily be indicative of results for the full year.

Gas and Liquids Stored Undergro

Gas and Liquids Stored Underground and Gas and NGLs Receivables and Payables	6 Months Ended
	Jun. 30, 2015
Gas Balancing Arrangements [Abstract]
Gas and Liquids Stored Underground and Gas and NGLs Receivables and Payables [Text Block]	Note 2: Gas and Liquids Stored Underground and Gas and NGLs Receivables and Payables Subsidiaries of the Partnership provide storage services whereby they store natural gas or NGLs on behalf of customers and also periodically hold customer gas under parking and lending (PAL) services. Since the customers retain title to the gas held by the Partnership in providing these services, the Partnership does not record the related gas on its balance sheet. Subsidiaries of the Partnership also periodically lend gas to customers under PAL and no-notice services. As of June 30, 2015 , the amount of gas owed to the subsidiaries of the Partnership due to gas imbalances and gas loaned under PAL and no-notice services was approximately 17.2 trillion British thermal units (TBtu). Assuming an average market price during June 2015 of $2.70 per million British thermal unit, the market value of that gas was approximately $46.4 million . As of June 30, 2015 , the amount of NGLs owed to the operating subsidiaries due to imbalances was 0.3 million barrels (MMBbls), which had a market value of approximately $9.4 million . As of December 31, 2014 , the amount of gas owed to the subsidiaries of the Partnership due to gas imbalances and gas loaned under PAL and no-notice services was approximately 10.0 TBtu. As of December 31, 2014 , the amount of NGLs owed to the operating subsidiaries due to imbalances was less than 0.1 MMBbls. If any significant customer should have credit or financial problems resulting in a delay or failure to repay the gas owed to the operating subsidiaries, it could have a material adverse effect on the Partnership’s financial condition, results of operations or cash flows.

Fair Value Measurements and Oth

Fair Value Measurements and Other Comprehensive Income (OCI)	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Derivatives and Fair Value [Text Block]	Note 3: Fair Value Measurements and Other Comprehensive Income (OCI) As discussed in Note 3 to the Partnership’s 2014 Annual Report on Form 10-K, the Partnership and the Williams Companies, Inc. formed joint ventures for the development of the Bluegrass project, a project between the Partnership, BPHC and The Williams Companies, Inc. (Bluegrass Project). In 2014 , the assets related to the joint ventures were determined to be impaired and were measured at fair value on a non-recurring basis. As a result, in the first quarter 2014, the Bluegrass Project entities, which were dissolved in December 2014, expensed the previously capitalized project costs, resulting in a $92.9 million charge which was reflected in Equity losses in unconsolidated affiliates and Asset impairment on the income statement. Net of noncontrolling interests of $82.9 million , these expenses reduced the Partnership's Net income attributable to controlling interests by $10.0 million . OCI The Partnership had no outstanding derivatives at June 30, 2015 , and December 31, 2014 , but had $9.6 million and $10.8 million of Accumulated other comprehensive loss (AOCI) related to cash flow hedges as of June 30, 2015 , and December 31, 2014 , which relate to previously settled treasury rate locks that are being amortized to earnings over the terms of the related interest payments, generally the terms of the related debt. The Partnership estimates that approximately $2.4 million of net losses from cash flow hedges reported in AOCI as of June 30, 2015 , are expected to be reclassified into earnings within the next twelve months. The following table shows the components and reclassifications to net income of AOCI which is included in Partners' Capital on the Condensed Consolidated Balance Sheets for the three months ended June 30, 2015 (in millions): Cash Flow Hedges Pension and Other Postretirement Costs Total Beginning balance, April 1, 2015 $ (10.2 ) $ (64.1 ) $ (74.3 ) Reclassifications: Interest expense 0.6 — 0.6 Pension and other postretirement benefit costs — (2.2 ) (2.2 ) Ending balance, June 30, 2015 $ (9.6 ) $ (66.3 ) $ (75.9 ) The following table shows the components and reclassifications to net income of AOCI which is included in Partners' Capital on the Condensed Consolidated Balance Sheets for the three months ended June 30, 2014 (in millions): Cash Flow Hedges Pension and Other Postretirement Costs Total Beginning balance, April 1, 2014 $ (12.7 ) $ (53.0 ) $ (65.7 ) Reclassifications: Transportation operating revenues 0.1 — 0.1 Interest expense 0.6 — 0.6 Pension and other postretirement benefit costs — (2.0 ) (2.0 ) Ending balance, June 30, 2014 $ (12.0 ) $ (55.0 ) $ (67.0 ) The following table shows the components and reclassifications to net income of AOCI which is included in Partners' Capital on the Condensed Consolidated Balance Sheets for the six months ended June 30, 2015 (in millions): Cash Flow Hedges Pension and Other Postretirement Costs Total Beginning balance, January 1, 2015 $ (10.8 ) $ (62.0 ) $ (72.8 ) Reclassifications: Interest expense 1.2 — 1.2 Pension and other postretirement benefit costs — (4.3 ) (4.3 ) Ending balance, June 30, 2015 $ (9.6 ) $ (66.3 ) $ (75.9 ) The following table shows the components and reclassifications to net income of AOCI which is included in Partners' Capital on the Condensed Consolidated Balance Sheets for the six months ended June 30, 2014 (in millions): Cash Flow Hedges Pension and Other Postretirement Costs Total Beginning balance, January 1, 2014 $ (12.7 ) $ (51.1 ) $ (63.8 ) Loss recorded in accumulated other comprehensive loss (0.9 ) — (0.9 ) Reclassifications: Transportation operating revenues 0.2 — 0.2 Other operating revenues 0.2 — 0.2 Interest expense 1.2 — 1.2 Pension and other postretirement benefit costs — (3.9 ) (3.9 ) Ending balance, June 30, 2014 $ (12.0 ) $ (55.0 ) $ (67.0 ) Financial Assets and Liabilities The following methods and assumptions were used in estimating the fair value amounts included in the disclosures for financial assets and liabilities, which are consistent with those disclosed in the 2014 Annual Report on Form 10-K: Cash and Cash Equivalents: For cash and short-term financial assets, the carrying amount is a reasonable estimate of fair value due to the short maturity of those instruments. Long-Term Debt: The estimated fair value of the Partnership's publicly traded debt is based on quoted market prices at June 30, 2015 , and December 31, 2014 . The fair market value of the debt that is not publicly traded is based on market prices of similar debt at June 30, 2015 , and December 31, 2014 . The carrying amount of the Partnership's variable-rate debt approximates fair value because the instruments bear a floating market-based interest rate. The carrying amount and estimated fair values of the Partnership's financial assets and liabilities which are not recorded at fair value on the Condensed Consolidated Balance Sheets as of June 30, 2015 , and December 31, 2014 , were as follows (in millions): As of June 30, 2015 Estimated Fair Value Financial Assets Carrying Amount Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 19.3 $ 19.3 $ — $ — $ 19.3 Financial Liabilities Long-term debt $ 3,484.2 (1) $ — $ 3,536.3 $ — $ 3,536.3 (1) The carrying amount of long-term debt excludes a $9.4 million capital lease obligation. As of December 31, 2014 Estimated Fair Value Financial Assets Carrying Amount Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 6.6 $ 6.6 $ — $ — $ 6.6 Financial Liabilities Long-term debt $ 3,680.1 (1) $ — $ 3,787.4 $ — $ 3,787.4 (1) The carrying amount of long-term debt excludes a $9.6 million capital lease obligation.

Property, Plant and Equipment

Property, Plant and Equipment	6 Months Ended
Property, Plant and Equipment	Jun. 30, 2015
Text Block [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	Note 4: Property, Plant and Equipment Asset Impairment Charges The Partnership recognized asset impairment charges of $1.4 million and $8.6 million for the three and six months ended June 30, 2014, related to an increase in the estimate of asset retirement obligations related to retired assets and the terminated Bluegrass Project.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies [Text Block]	Note 5: Commitments and Contingencies Legal Proceedings and Settlements The Partnership's subsidiaries are parties to various legal actions arising in the normal course of business. Management believes the disposition of these outstanding legal actions will not have a material impact on the Partnership's financial condition, results of operations or cash flows. Southeast Louisiana Flood Protection Litigation The Partnership and its subsidiary, Gulf South Pipeline Company, LP (Gulf South), along with approximately 100 other energy companies operating in Southern Louisiana, have been named as defendants in a petition for damages and injunctive relief in state district court for Orleans Parish, Louisiana (Case No. 13-6911) by the Board of Commissioners of the Southeast Louisiana Flood Protection Authority - East (Flood Protection Authority). The case was filed in state court, but was removed to the United States District Court for the Eastern District of New Orleans (Court) in August 2013. The lawsuit claims include negligence, strict liability, public nuisance, private nuisance, breach of contract, and breach of the natural servitude of drain against the defendants, alleging that the defendants’ drilling, dredging, pipeline and industrial operations since the 1930s have caused increased storm surge risk, increased flood protection costs and unspecified damages to the Flood Protection Authority. In addition to attorney fees and unspecified monetary damages, the lawsuit seeks abatement and restoration of the coastal lands, including backfilling and revegetating of canals dredged and used by the defendants, and abatement and restoration activities such as wetlands creation, reef creation, land bridge construction, hydrologic restoration, shoreline protection, structural protection, bank stabilization, and ridge restoration. On February 13, 2015, the Court dismissed the case with prejudice. The Flood Protection Authority has appealed the dismissal of the case to the U.S. Court of Appeals for the Fifth Circuit. Gulf South, along with several other energy companies, has also been named as a defendant in a petition for damages and injunctive relief filed by Joseph Bernstein (Case No. 744-226) and the Defelice Land Company, L.L.C. (Case No. 61-926). These cases are similar in nature to the Flood Protection Authority case discussed above. Both cases were originally filed in Louisiana district court and were moved to federal court. In the second quarter 2015, the cases were remanded to Louisiana district court. Regulatory Matters In October 2014, Gulf South filed a rate case with the Federal Energy Regulatory Commission (FERC) pursuant to Section 4 of the Natural Gas Act (Docket No. RP15-65), requesting, among other things, a reconfiguration of the transportation rate zones on its system and, in general, an increase in its tariff rates for those customers whose agreements are at maximum tariff rates. On May 1, 2015, Gulf South moved the filed tariff rates into effect. The resulting increased revenues are subject to potential refund; therefore, the Partnership recognized a liability for a portion of the incremental amount collected based on an assessment of the rate case proceedings, discussions with customers and FERC, advice of counsel and other factors. The actual amount of any potential refund will be determined when the rate case is ultimately settled and approved by FERC. In the second quarter 2015, the Partnership recognized $5.7 million of additional operating revenues as a result of the rate case. Insurance Proceeds For the three and six months ended June 30, 2015, the Partnership received $6.3 million in proceeds from a business interruption claim related to Boardwalk Louisiana Midstream, LLC, which was recorded in Transportation revenues. Subsequent to June 30, 2015, the Partnership received an additional $2.5 million in proceeds related to the business interruption claim. No additional amounts are expected to be received. Environmental and Safety Matters The operating subsidiaries are subject to federal, state and local environmental laws and regulations in connection with the operation and remediation of various operating sites. As of June 30, 2015 , and December 31, 2014 , the Partnership had an accrued liability of approximately $5.2 million and $6.1 million related to assessment and/or remediation costs associated with the historical use of polychlorinated biphenyls, petroleum hydrocarbons and mercury, groundwater protection measures and other costs. The liability represents management’s estimate of the undiscounted future obligations based on evaluations and discussions with counsel and operating personnel and the current facts and circumstances related to these matters. The related expenditures are expected to occur over the next seven years. As of June 30, 2015 , and December 31, 2014 , approximately $1.5 million was recorded in Other current liabilities and approximately $3.7 million and $4.6 million were recorded in Other Liabilities and Deferred Credits . Commitments for Construction The Partnership’s future capital commitments are comprised of binding commitments under purchase orders for materials ordered but not received and firm commitments under binding construction service agreements. The commitments as of June 30, 2015 , were approximately $155.1 million , all of which are expected to be settled within the next twelve months. There were no substantial changes to the Partnership’s operating lease commitments, pipeline capacity agreements or capital lease obligation disclosed in Note 5 to the Partnership’s 2014 Annual Report on Form 10-K.

Cash Distributions and Net Inco

Cash Distributions and Net Income per Unit	6 Months Ended
Cash Distributions and Net Income per Unit	Jun. 30, 2015
Partners' Capital Notes [Abstract]
Cash Distributions and Net Income per Unit [Text Block]	Note 6: Cash Distributions and Net Income per Unit Cash Distributions In the second quarters 2015 and 2014 , the Partnership declared and paid quarterly distributions to its common unitholders of record of $0.10 per common unit and an amount to the general partner on behalf of its 2% general partner interest. In July 2015 , the Partnership declared a quarterly cash distribution to unitholders of record of $0.10 per common unit. Net Income per Unit For purposes of calculating net income per unit, net income for the current period is reduced by the amount of available cash that will be distributed with respect to that period. Payments made on account of the Partnership’s various ownership interests are determined in relation to actual declared distributions, and are not based on the assumed allocations required under GAAP. Any residual amount representing undistributed net income is assumed to be allocated to the various ownership interests in accordance with the contractual provisions of the partnership agreement on a pro rata basis. Net income per unit is calculated based on the weighted-average number of units outstanding for the period. The following table provides a reconciliation of net income and the assumed allocation of net income to the common units for purposes of computing net income per unit for the three months ended June 30, 2015 , (in millions, except per unit data): Total Common Units General Partner and IDRs Net income $ 40.4 Declared distribution 25.6 $ 25.1 $ 0.5 Assumed allocation of undistributed net income 14.8 14.5 0.3 Assumed allocation of net income attributable to limited partner unitholders and general partner $ 40.4 $ 39.6 $ 0.8 Weighted-average units outstanding 250.3 Net income per unit $ 0.16 The following table provides a reconciliation of net income and the assumed allocation of net income to the common units for purposes of computing net income per unit for the three months ended June 30, 2014 , (in millions, except per unit data): Total Common Units General Partner and IDRs Net income $ 55.9 Less: Net loss attributable to noncontrolling interests (1.5 ) Net income attributable to controlling interests 57.4 Declared distribution 24.8 $ 24.3 $ 0.5 Assumed allocation of undistributed net income 32.6 32.0 0.6 Assumed allocation of net income attributable to limited partner unitholders and general partner $ 57.4 $ 56.3 $ 1.1 Weighted-average units outstanding 243.3 Net income per unit $ 0.23 The following table provides a reconciliation of net income and the assumed allocation of net income to the common units for purposes of computing net income per unit for the six months ended June 30, 2015 , (in millions, except per unit data): Total Common Units General Partner and IDRs Net income $ 118.1 Declared distribution 51.1 $ 50.1 $ 1.0 Assumed allocation of undistributed net income 67.0 65.7 1.3 Assumed allocation of net income attributable to limited partner unitholders and general partner $ 118.1 $ 115.8 $ 2.3 Weighted-average units outstanding 247.3 Net income per unit $ 0.47 The following table provides a reconciliation of net income and the assumed allocation of net income to the common units for purposes of computing net income per unit for the six months ended June 30, 2014 , (in millions, except per unit data): Total Common Units General Partner and IDRs Net income $ 81.5 Less: Net loss attributable to noncontrolling interests (86.1 ) Net income attributable to controlling interests 167.6 Declared distribution 49.6 $ 48.7 $ 0.9 Assumed allocation of undistributed net income 118.0 115.6 2.4 Assumed allocation of net income attributable to limited partner unitholders and general partner $ 167.6 $ 164.3 $ 3.3 Weighted-average units outstanding 243.3 Net income per unit $ 0.68

Financing

Financing	6 Months Ended
Financing	Jun. 30, 2015
Debt Disclosure [Abstract]
Financing [Text Block]	Note 7: Financing Notes and Debentures As of June 30, 2015 , and December 31, 2014 , the Partnership had notes and debentures outstanding of $3.1 billion and $3.4 billion with a weighted-average interest rate of 5.32% and 5.31% . Issuance of Notes In March 2015, the Partnership completed an additional issuance of its 4.95% senior notes due 2024 (Boardwalk Pipelines 2024 Notes), of which $350.0 million were originally issued in November 2014 (in millions, except interest rates): Date of Issuance Issuing Subsidiary Amount of Issuance Purchaser Discounts and Expenses Net Proceeds Interest Rate Maturity Date Interest Payable March 2015 Boardwalk Pipelines $ 250.0 $ 2.9 $ 247.1 (1) 4.95% December 15, 2024 June 15 and December 15 (1) The net proceeds of this offering were used to retire a portion of the outstanding $250.0 million aggregate principal amount of Texas Gas Transmission, LLC's (Texas Gas) 4.60% notes that matured in June 2015 (Texas Gas 2015 Notes). Initially, the Partnership used the net proceeds to reduce outstanding borrowings under its revolving credit facility. Subsequently, on June 1, 2015, the Partnership retired the Texas Gas 2015 Notes with borrowings under its revolving credit facility. The indentures governing the notes and debentures have restrictive covenants which provide that, with certain exceptions, neither the Partnership nor any of its subsidiaries may create, assume or suffer to exist any lien upon any property to secure any indebtedness unless the debentures and notes shall be equally and ratably secured. All debt obligations are unsecured. At June 30, 2015 , the Partnership and its subsidiaries were in compliance with their debt covenants. Redemption of Notes In 2015, the outstanding $275.0 million aggregate principal amount of Gulf South's 5.05% notes due 2015 and the Texas Gas 2015 Notes were retired at maturity with the proceeds received from the issuance of Boardwalk Pipelines 2024 Notes. Revolving Credit Facility In May 2015, the Partnership entered into a Third Amended and Restated Revolving Credit Agreement (Amended Credit Agreement or credit facility) with Wells Fargo Bank, N.A., as administrative agent, having aggregate lending commitments of $1.5 billion , a maturity date of May 26, 2020 , and including Boardwalk Pipelines, Texas Gas, Gulf South and Gulf Crossing Pipeline Company LLC as borrowers. Interest is determined, at the Partnership’s election, by reference to (a) the base rate which is the highest of (1) the prime rate , (2) the federal funds rate plus 0.50% , and (3) the one month Eurodollar Rate plus 1.00% , plus an applicable margin, or (b) the London Interbank Offered Rate ( LIBOR ) plus an applicable margin. The applicable margin ranges from 0.00% to 0.75% for loans bearing interest based on the base rate and ranges from 1.00% to 1.75% for loans bearing interest based on the LIBOR Rate, in each case determined based on the individual Borrower’s credit rating from time to time. The Amended Credit Agreement also provides for a quarterly commitment fee charged on the average daily unused amount of the revolving credit facility ranging from 0.10% to 0.275% and determined based on the individual Borrower’s credit rating from time to time. The credit facility contains various restrictive covenants and other usual and customary terms and conditions, including restrictions regarding the incurrence of additional debt, the sale of assets and sale-leaseback transactions. The financial covenants under the credit facility require the Partnership and its subsidiaries to maintain, among other things, a ratio of total consolidated debt to consolidated EBITDA (as defined in the credit agreement) measured for the previous twelve months of not more than 5.0 to 1.0 , or up to 5.5 to 1.0 for the three quarters following the quarter of an acquisition. The Partnership and its subsidiaries were in compliance with all covenant requirements under the credit facility as of June 30, 2015 . Outstanding borrowings under the Partnership’s revolving credit facility as of June 30, 2015 , and December 31, 2014 , were $400.0 million and $120.0 million , with a weighted-average borrowing rate of 1.44% and 1.54% . As of August 3, 2015 , the Partnership had $400.0 million outstanding borrowings under its credit facility, resulting in an available borrowing capacity of $1.1 billion . Term Loan The Partnership had a variable-rate term loan due October 1, 2017 (Term Loan). At December 31, 2014 , outstanding borrowings under the Term Loan were $200.0 million , with a weighted-average borrowing interest rate of 1.91% . The Partnership repaid all outstanding borrowings in 2015 and terminated all related commitments. Subordinated Debt Agreement with Affiliate In 2014, the Partnership entered into a Subordinated Loan Agreement with BPHC under which the Partnership can borrow up to $300.0 million (Subordinated Loan) through December 31, 2015. The Subordinated Loan bears interest at increasing rates, ranging from 5.75% to 9.75% , payable semi-annually in June and December, and matures in July 2024 . The Subordinated Loan must be prepaid with the net cash proceeds from the issuance of additional equity securities by the Partnership or the incurrence of certain indebtedness by the Partnership or its subsidiaries, although BPHC may waive such prepayment. The Subordinated Loan is subordinated in right of payment to the Partnership’s obligations under its revolving credit facility pursuant to the terms of a Subordination Agreement between BPHC and Wells Fargo, N.A., as representative of the lenders under the revolving credit facility. Through the filing date of this Quarterly Report on Form 10-Q, the Partnership has not borrowed any amounts under the Subordinated Loan. Issuance of Common Units The Partnership has an effective registration statement on file with the SEC for the issuance of up to $500.0 million of the Partnership's common units. Under the registration statement, pursuant to an equity distribution agreement between the Partnership and certain broker-dealers, the Partnership may sell its common units from time to time through the broker-dealers as the Partnership’s sales agents. Sales of common units can be made by means of ordinary brokers’ transactions on the NYSE or as otherwise agreed by the Partnership and one or more of the broker-dealers. During the six months ended June 30, 2015, the Partnership sold 7.0 million common units under its equity distribution agreement and received net proceeds of $115.4 million , including a $2.3 million contribution received from its general partner to maintain its 2% general partner interest.

Employee Benefits

Employee Benefits	6 Months Ended
Employee Benefits	Jun. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Employee Benefits [Text Block]	Note 8: Employee Benefits Defined Benefit Retirement Plans and Postretirement Benefits Other Than Pension (PBOP) Texas Gas employees hired prior to November 2006 are covered under a non-contributory, defined benefit pension plan (Pension Plan). The Texas Gas Supplemental Retirement Plan (SRP) provides pension benefits for the portion of an eligible employee’s pension benefit under the Pension Plan that becomes subject to compensation limitations under the Internal Revenue Code. Collectively, the Partnership refers to the Pension Plan and the SRP as Retirement Plans. Texas Gas provides postretirement medical benefits and life insurance to retired employees who were employed full time, hired prior to 1996, and met certain other requirements. Components of net periodic benefit cost for both the Retirement Plans and PBOP for the three months ended June 30, 2015 and 2014 were as follows (in millions): Retirement Plans PBOP For the For the 2015 2014 2015 2014 Service cost $ 1.0 $ 1.0 $ 0.1 $ 0.1 Interest cost 1.2 1.4 0.5 0.6 Expected return on plan assets (2.3 ) (2.4 ) (1.1 ) (1.0 ) Amortization of prior service credit — — (1.9 ) (2.0 ) Amortization of unrecognized net loss 0.4 0.3 (0.1 ) — Regulatory asset decrease 0.5 0.5 — — Net periodic benefit cost $ 0.8 $ 0.8 $ (2.5 ) $ (2.3 ) Components of net periodic benefit cost for both the Retirement Plans and PBOP for the six months ended June 30, 2015 and 2014 were as follows (in millions): Retirement Plans PBOP For the For the 2015 2014 2015 2014 Service cost $ 2.0 $ 2.0 $ 0.2 $ 0.2 Interest cost 2.4 2.8 1.0 1.1 Expected return on plan assets (4.6 ) (4.7 ) (2.3 ) (2.1 ) Amortization of prior service credit — — (3.8 ) (3.9 ) Amortization of unrecognized net loss 0.8 0.6 — 0.1 Regulatory asset decrease 1.0 0.9 — — Net periodic benefit cost $ 1.6 $ 1.6 $ (4.9 ) $ (4.6 ) Through the date of this filing, the Partnership has not made contributions to the Pension Plan in 2015, but expects to fund $3.0 million in 2015. Defined Contribution Plans Texas Gas employees hired on or after November 1, 2006, and other employees of the Partnership are provided retirement benefits under a defined contribution money purchase plan. The Partnership also provides 401(k) plan benefits to its employees. Costs related to the Partnership’s defined contribution plans were $2.4 million and $2.3 million for the three months ended June 30, 2015 and 2014 , and $4.6 million and $4.4 million for the six months ended June 30, 2015 and 2014 .

Related Party Transactions

Related Party Transactions	6 Months Ended
Related Party Transactions	Jun. 30, 2015
Related Party Transactions [Abstract]
Related Party Transactions [Text Block]	Note 9: Related Party Transactions Loews provides a variety of corporate services to the Partnership under services agreements, including but not limited to, information technology, tax, risk management, internal audit and corporate development services, plus allocated overheads. The Partnership incurred charges related to these services of $2.2 million for each of the three months ended June 30, 2015 and 2014 , and $4.4 million for each of the six months ended June 30, 2015 and 2014 . Distributions paid related to limited partner units held by BPHC and the 2% general partner interest held by Boardwalk GP were $13.1 million and $13.0 million for the three months ended June 30, 2015 and 2014 , and $26.1 million and $26.0 million for the six months ended June 30, 2015 and 2014 . In 2013, the Partnership entered into agreements with BPHC to form two entities for the purpose of investing in the terminated Bluegrass Project. Through June 30, 2014 , the Partnership contributed $12.7 million and BPHC contributed $97.8 million of cash and other assets to these entities and the Partnership and BPHC received a $1.9 million and $7.1 million distribution from these entities.

Recently Issued Accounting Pron

Recently Issued Accounting Pronouncements	6 Months Ended
Recently Issued Accounting Pronouncements	Jun. 30, 2015
Disclosure Text Block [Abstract]
Recently Issued Accounting Pronouncements [Text Block]	Note 10: Recently Issued Accounting Pronouncements In May 2014, the Financial Accounting Standards Board issued Accounting Standards Update 2014-09 (ASU 2014-09), Revenue from Contracts with Customers (Topic 606), which will require entities to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. ASU 2014-09 also requires enhanced disclosures regarding the nature, amount, timing and uncertainty of revenues and cash flows from contracts with customers. ASU 2014-09 is effective for interim and annual reporting periods beginning after December 15, 2017, though an entity may elect to begin applying the provisions of the ASU for periods beginning after December 15, 2016. The Partnership is evaluating the impact, if any, that ASU 2014-09 will have on its financial statements.

Supplemental Disclosure of Cash

Supplemental Disclosure of Cash Flow Information	6 Months Ended
Supplemental Disclosure of Cash Flow Information	Jun. 30, 2015
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosure of Cash Flow Information [Text Block]	Note 11: Supplemental Disclosure of Cash Flow Information (in millions): For the 2015 2014 Cash paid during the period for: Interest (net of amount capitalized) $ 91.4 $ 76.1

Guarantee of Securities of Subs

Guarantee of Securities of Subsidiaries	6 Months Ended
Guarantee of Securities of Subsidiaries	Jun. 30, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Guarantee of Securities of Subsidiaries [Text Block]	Note 12: Guarantee of Securities of Subsidiaries Boardwalk Pipelines (subsidiary issuer) has issued securities which have been fully and unconditionally guaranteed by the Partnership (parent guarantor). The Partnership's subsidiaries have no significant restrictions on their ability to pay distributions or make loans to the Partnership except as noted in the debt covenants and have no restricted assets at June 30, 2015 , and December 31, 2014 . Note 7 contains additional information regarding the Partnership's debt and related covenants. The Partnership has provided the following condensed consolidating financial information in accordance with Regulation S-X Rule 3-10, Financial Statements of Guarantors and Issuers of Guaranteed Securities Registered or Being Registered . Condensed Consolidating Balance Sheets as of June 30, 2015 (Millions) Assets Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Cash and cash equivalents $ 0.5 $ 2.8 $ 16.0 $ — $ 19.3 Receivables 0.1 — 105.5 — 105.6 Receivables - affiliate — — 6.6 (6.6 ) — Gas and liquids stored underground — — 8.5 — 8.5 Prepayments 0.2 0.1 19.5 — 19.8 Advances to affiliates — 20.4 145.2 (165.6 ) — Other current assets — — 14.0 (5.1 ) 8.9 Total current assets 0.8 23.3 315.3 (177.3 ) 162.1 Investment in consolidated subsidiaries 2,072.6 6,915.7 — (8,988.3 ) — Property, plant and equipment, gross 0.6 — 9,498.0 — 9,498.6 Less–accumulated depreciation and amortization 0.6 — 1,923.0 — 1,923.6 Property, plant and equipment, net — — 7,575.0 — 7,575.0 Other noncurrent assets — 5.4 473.6 0.1 479.1 Advances to affiliates – noncurrent 2,226.0 502.3 1,008.8 (3,737.1 ) — Total other assets 2,226.0 507.7 1,482.4 (3,737.0 ) 479.1 Total Assets $ 4,299.4 $ 7,446.7 $ 9,372.7 $ (12,902.6 ) $ 8,216.2 Liabilities and Partners' Capital Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Payables $ 0.2 $ — $ 85.8 $ — $ 86.0 Payable to affiliates 0.9 — 6.6 (6.6 ) 0.9 Advances from affiliates — 145.2 20.4 (165.6 ) — Other current liabilities — 20.9 136.5 (5.1 ) 152.3 Total current liabilities 1.1 166.1 249.3 (177.3 ) 239.2 Long-term debt and capital lease obligation — 1,973.2 1,520.4 — 3,493.6 Payable to affiliate - noncurrent 16.0 — — — 16.0 Advances from affiliates - noncurrent — 3,234.8 502.3 (3,737.1 ) — Other noncurrent liabilities — — 185.0 0.1 185.1 Total other liabilities and deferred credits 16.0 3,234.8 687.3 (3,737.0 ) 201.1 Total partners' capital 4,282.3 2,072.6 6,915.7 (8,988.3 ) 4,282.3 Total Liabilities and Partners' Capital $ 4,299.4 $ 7,446.7 $ 9,372.7 $ (12,902.6 ) $ 8,216.2 Condensed Consolidating Balance Sheets as of December 31, 2014 (Millions) Assets Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Cash and cash equivalents $ 0.5 $ 1.8 $ 4.3 $ — $ 6.6 Receivables — — 110.9 — 110.9 Receivables - affiliate — — 9.0 (9.0 ) — Gas and liquids stored underground — — 4.1 — 4.1 Prepayments 0.1 — 14.4 — 14.5 Advances to affiliates — 6.3 106.2 (112.5 ) — Other current assets 0.5 — 19.2 (6.2 ) 13.5 Total current assets 1.1 8.1 268.1 (127.7 ) 149.6 Investment in consolidated subsidiaries 1,970.6 6,744.1 — (8,714.7 ) — Property, plant and equipment, gross 0.6 — 9,355.0 — 9,355.6 Less–accumulated depreciation and amortization 0.6 — 1,765.8 — 1,766.4 Property, plant and equipment, net — — 7,589.2 — 7,589.2 Other noncurrent assets — 3.4 465.2 (0.6 ) 468.0 Advances to affiliates – noncurrent 2,148.3 212.0 996.5 (3,356.8 ) — Total other assets 2,148.3 215.4 1,461.7 (3,357.4 ) 468.0 Total Assets $ 4,120.0 $ 6,967.6 $ 9,319.0 $ (12,199.8 ) $ 8,206.8 Liabilities and Partners' Capital Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Payables $ 0.2 $ 0.1 $ 61.8 $ — $ 62.1 Payable to affiliates 1.5 — 9.0 (9.0 ) 1.5 Advances from affiliates — 106.2 6.3 (112.5 ) — Other current liabilities — 21.4 141.7 (6.5 ) 156.6 Total current liabilities 1.7 127.7 218.8 (128.0 ) 220.2 Long-term debt and capital lease obligation — 1,724.5 1,965.2 — 3,689.7 Payable to affiliate - noncurrent 16.0 — — — 16.0 Advances from affiliates - noncurrent — 3,144.8 212.0 (3,356.8 ) — Other noncurrent liabilities — — 178.9 (0.3 ) 178.6 Total other liabilities and deferred credits 16.0 3,144.8 390.9 (3,357.1 ) 194.6 Total partners' capital 4,102.3 1,970.6 6,744.1 (8,714.7 ) 4,102.3 Total Liabilities and Partners' Capital $ 4,120.0 $ 6,967.6 $ 9,319.0 $ (12,199.8 ) $ 8,206.8 Condensed Consolidating Statements of Income for the Three Months Ended June 30, 2015 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Operating Revenues: Transportation $ — $ — $ 278.6 $ (21.7 ) $ 256.9 Parking and lending — — 3.0 (0.2 ) 2.8 Storage — — 20.9 — 20.9 Other — — 18.0 — 18.0 Total operating revenues — — 320.5 (21.9 ) 298.6 Operating Costs and Expenses: Fuel and transportation — — 45.5 (21.9 ) 23.6 Operation and maintenance — — 54.6 — 54.6 Administrative and general (0.2 ) — 32.0 — 31.8 Other operating costs and expenses 0.2 — 102.5 — 102.7 Total operating costs and expenses — — 234.6 (21.9 ) 212.7 Operating income — — 85.9 — 85.9 Other Deductions (Income): Interest expense — 27.9 18.0 — 45.9 Interest (income) expense - affiliates, net (7.2 ) 9.1 (1.9 ) — — Interest income — — (0.1 ) — (0.1 ) Equity in earnings of subsidiaries (33.2 ) (70.2 ) — 103.4 — Miscellaneous other income, net — — (0.4 ) — (0.4 ) Total other (income) deductions (40.4 ) (33.2 ) 15.6 103.4 45.4 Income (loss) before income taxes 40.4 33.2 70.3 (103.4 ) 40.5 Income taxes — — 0.1 — 0.1 Net income (loss) $ 40.4 $ 33.2 $ 70.2 $ (103.4 ) $ 40.4 Condensed Consolidating Statements of Income for the Three Months Ended June 30, 2014 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Operating Revenues: Transportation $ — $ — $ 268.5 $ (22.8 ) $ 245.7 Parking and lending — — 9.2 — 9.2 Storage — — 22.2 (0.1 ) 22.1 Other — — 16.4 — 16.4 Total operating revenues — — 316.3 (22.9 ) 293.4 Operating Costs and Expenses: Fuel and transportation — — 52.8 (22.9 ) 29.9 Operation and maintenance — — 43.9 — 43.9 Administrative and general — — 30.5 — 30.5 Other operating costs and expenses — — 92.6 — 92.6 Total operating costs and expenses — — 219.8 (22.9 ) 196.9 Operating income — — 96.5 — 96.5 Other Deductions (Income): Interest expense — 18.7 21.5 — 40.2 Interest (income) expense - affiliates, net (7.6 ) 10.2 (2.6 ) — — Interest income — — (0.2 ) — (0.2 ) Equity in earnings of subsidiaries (49.8 ) (78.7 ) — 128.5 — Equity losses in unconsolidated affiliates — — 0.5 — 0.5 Total other (income) deductions (57.4 ) (49.8 ) 19.2 128.5 40.5 Income (loss) before income taxes 57.4 49.8 77.3 (128.5 ) 56.0 Income taxes — — 0.1 — 0.1 Net income (loss) 57.4 49.8 77.2 (128.5 ) 55.9 Net loss attributable to noncontrolling interests — — (1.5 ) — (1.5 ) Net income (loss) attributable to controlling interests $ 57.4 $ 49.8 $ 78.7 $ (128.5 ) $ 57.4 Condensed Consolidating Statements of Income for the Six Months Ended June 30, 2015 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Operating Revenues: Transportation $ — $ — $ 590.2 $ (43.7 ) $ 546.5 Parking and lending — — 5.8 (0.2 ) 5.6 Storage — — 40.2 — 40.2 Other — — 36.0 — 36.0 Total operating revenues — — 672.2 (43.9 ) 628.3 Operating Costs and Expenses: Fuel and transportation — — 94.5 (43.9 ) 50.6 Operation and maintenance — — 97.0 — 97.0 Administrative and general (0.2 ) — 62.6 — 62.4 Other operating costs and expenses 0.2 — 209.4 — 209.6 Total operating costs and expenses — — 463.5 (43.9 ) 419.6 Operating income — — 208.7 — 208.7 Other Deductions (Income): Interest expense — 51.8 39.3 — 91.1 Interest (income) expense - affiliates, net (13.9 ) 18.6 (4.7 ) — — Interest income — — (0.2 ) — (0.2 ) Equity in earnings of subsidiaries (104.2 ) (174.6 ) — 278.8 — Miscellaneous other income, net — — (0.6 ) — (0.6 ) Total other (income) deductions (118.1 ) (104.2 ) 33.8 278.8 90.3 Income (loss) before income taxes 118.1 104.2 174.9 (278.8 ) 118.4 Income taxes — — 0.3 — 0.3 Net income (loss) $ 118.1 $ 104.2 $ 174.6 $ (278.8 ) $ 118.1 Condensed Consolidating Statements of Income for the Six Months Ended June 30, 2014 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Operating Revenues: Transportation $ — $ — $ 595.6 $ (45.6 ) $ 550.0 Parking and lending — — 18.4 — 18.4 Storage — — 51.0 (0.1 ) 50.9 Other — — 31.0 — 31.0 Total operating revenues — — 696.0 (45.7 ) 650.3 Operating Costs and Expenses: Fuel and transportation — — 108.6 (45.7 ) 62.9 Operation and maintenance — — 86.6 — 86.6 Administrative and general (0.1 ) — 57.4 — 57.3 Other operating costs and expenses 0.1 — 194.3 — 194.4 Total operating costs and expenses — — 446.9 (45.7 ) 401.2 Operating income — — 249.1 — 249.1 Other Deductions (Income): Interest expense — 37.4 43.7 — 81.1 Interest (income) expense - affiliates, net (15.4 ) 20.4 (5.0 ) — — Interest income — — (0.3 ) — (0.3 ) Equity in earnings of subsidiaries (152.2 ) (210.0 ) — 362.2 — Equity losses in unconsolidated affiliates — — 86.6 — 86.6 Miscellaneous other income, net — — (0.1 ) — (0.1 ) Total other (income) deductions (167.6 ) (152.2 ) 124.9 362.2 167.3 Income (loss) before income taxes 167.6 152.2 124.2 (362.2 ) 81.8 Income taxes — — 0.3 — 0.3 Net income (loss) 167.6 152.2 123.9 (362.2 ) 81.5 Net loss attributable to noncontrolling interests — — (86.1 ) — (86.1 ) Net income (loss) attributable to controlling interests $ 167.6 $ 152.2 $ 210.0 $ (362.2 ) $ 167.6 Condensed Consolidating Statements of Comprehensive Income for the Three Months Ended June 30, 2015 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Net income (loss) $ 40.4 $ 33.2 $ 70.2 $ (103.4 ) $ 40.4 Other comprehensive income (loss): Reclassification adjustment transferred to Net Income from cash flow hedges 0.6 0.6 0.2 (0.8 ) 0.6 Pension and other postretirement benefit costs (2.2 ) (2.2 ) (2.2 ) 4.4 (2.2 ) Total Comprehensive Income (Loss) $ 38.8 $ 31.6 $ 68.2 $ (99.8 ) $ 38.8 Condensed Consolidating Statements of Comprehensive Income for the Three Months Ended June 30, 2014 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Net income (loss) $ 57.4 $ 49.8 $ 77.2 $ (128.5 ) $ 55.9 Other comprehensive income (loss) : Reclassification adjustment transferred to Net Income from cash flow hedges 0.7 0.7 0.3 (1.0 ) 0.7 Pension and other postretirement benefit costs (2.0 ) (2.0 ) (2.0 ) 4.0 (2.0 ) Total Comprehensive Income (Loss) 56.1 48.5 75.5 (125.5 ) 54.6 Comprehensive loss attributable to noncontrolling interests — — (1.5 ) — (1.5 ) Comprehensive income (loss) attributable to controlling interests $ 56.1 $ 48.5 $ 77.0 $ (125.5 ) $ 56.1 Condensed Consolidating Statements of Comprehensive Income for the Six Months Ended June 30, 2015 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Net income (loss) $ 118.1 $ 104.2 $ 174.6 $ (278.8 ) $ 118.1 Other comprehensive income (loss): Reclassification adjustment transferred to Net Income from cash flow hedges 1.2 1.2 0.4 (1.6 ) 1.2 Pension and other postretirement benefit costs (4.3 ) (4.3 ) (4.3 ) 8.6 (4.3 ) Total Comprehensive Income (Loss) $ 115.0 $ 101.1 $ 170.7 $ (271.8 ) $ 115.0 Condensed Consolidating Statements of Comprehensive Income for the Six Months Ended June 30, 2014 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Net income (loss) $ 167.6 $ 152.2 $ 123.9 $ (362.2 ) $ 81.5 Other comprehensive income (loss): (Loss) gain on cash flow hedges (0.9 ) (0.9 ) (0.9 ) 1.8 (0.9 ) Reclassification adjustment transferred to Net Income from cash flow hedges 1.6 1.6 0.8 (2.4 ) 1.6 Pension and other postretirement benefit costs (3.9 ) (3.9 ) (3.9 ) 7.8 (3.9 ) Total Comprehensive Income (Loss) 164.4 149.0 119.9 (355.0 ) 78.3 Comprehensive loss attributable to noncontrolling interests — — (86.1 ) — (86.1 ) Comprehensive income (loss) attributable to controlling interests $ 164.4 $ 149.0 $ 206.0 $ (355.0 ) $ 164.4 Condensed Consolidating Statements of Cash Flow for the Six Months Ended June 30, 2015 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Net cash provided by (used in) operating activities $ 12.6 $ (67.1 ) $ 340.0 $ — $ 285.5 INVESTING ACTIVITIES: Capital expenditures — — (136.3 ) — (136.3 ) Proceeds from sale of operating assets — — 0.1 — 0.1 Advances to affiliates, net (77.7 ) (304.4 ) (51.3 ) 433.4 — Net cash (used in) provided by investing activities (77.7 ) (304.4 ) (187.5 ) 433.4 (136.2 ) FINANCING ACTIVITIES: Proceeds from long-term debt — 247.1 — — 247.1 Repayment of borrowings from long-term debt and term loan — — (725.0 ) — (725.0 ) Proceeds from borrowings on revolving credit agreement — — 835.0 — 835.0 Repayment of borrowings on revolving credit agreement, including financing fees — (3.6 ) (555.0 ) — (558.6 ) Principal payment of capital lease obligation — — (0.2 ) — (0.2 ) Advances from affiliates, net 0.1 129.0 304.4 (433.4 ) 0.1 Distributions paid (50.4 ) — — — (50.4 ) Proceeds from sale of common units 113.1 — — — 113.1 Capital contributions from general partner 2.3 — — — 2.3 Net cash provided by (used in) financing activities 65.1 — 372.5 — (140.8 ) — (433.4 ) — (136.6 ) Increase in cash and cash equivalents — 1.0 11.7 — 12.7 Cash and cash equivalents at beginning of period 0.5 1.8 4.3 — 6.6 Cash and cash equivalents at end of period $ 0.5 $ 2.8 $ 16.0 $ — $ 19.3 Condensed Consolidating Statements of Cash Flow for the Six Months Ended June 30, 2014 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Net cash provided by (used in) operating activities $ 15.5 $ (55.8 ) $ 348.4 $ — $ 308.1 INVESTING ACTIVITIES: Capital expenditures — — (162.7 ) — (162.7 ) Proceeds from sale of operating assets — — 2.9 — 2.9 Advances to affiliates, net 33.8 (16.6 ) (98.8 ) 81.7 0.1 Investment in unconsolidated affiliates — — (20.3 ) — (20.3 ) Distributions from unconsolidated affiliates — — 10.7 — 10.7 Net cash provided by (used in) investing activities 33.8 (16.6 ) (268.2 ) 81.7 (169.3 ) FINANCING ACTIVITIES: Proceeds from borrowings on revolving credit agreement — — 220.0 — 220.0 Repayment of borrowings on revolving credit agreement — — (295.0 ) — (295.0 ) Principal payment of capital lease obligation — — (0.2 ) — (0.2 ) Advances from affiliates, net 0.1 65.1 16.6 (81.7 ) 0.1 Distributions paid (49.6 ) — — — (49.6 ) Capital contributions from noncontrolling interests — — 7.8 — 7.8 Distributions paid to noncontrolling interests — — (7.1 ) — (7.1 ) Net cash (used in) provided by financing activities (49.5 ) 65.1 (57.9 ) (81.7 ) (124.0 ) (Decrease) increase in cash and cash equivalents (0.2 ) (7.3 ) 22.3 — 14.8 Cash and cash equivalents at beginning of period 0.2 9.2 19.1 — 28.5 Cash and cash equivalents at end of period $ — $ 1.9 $ 41.4 $ — $ 43.3

Basis of Presentation (Policies

Basis of Presentation (Policies)	6 Months Ended
Basis of Presentation (Policies)	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting, Policy [Policy Text Block]	The accompanying unaudited condensed consolidated financial statements of the Partnership were prepared pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) have been condensed or omitted pursuant to such rules and regulations. In the opinion of management, the accompanying condensed consolidated financial statements reflect all adjustments (consisting of only normal recurring accruals) necessary to present fairly the financial position as of June 30, 2015 , and December 31, 2014 , and the results of operations and comprehensive income for the three and six months ended June 30, 2015 and 2014 , and changes in cash flows and changes in equity for the six months ended June 30, 2015 and 2014 . Reference is made to the Notes to Consolidated Financial Statements in the Annual Report on Form 10-K for the year ended December 31, 2014 ( 2014 Annual Report on Form 10-K), which should be read in conjunction with these unaudited condensed consolidated financial statements. The accounting policies described in Note 2 to the Consolidated Financial Statements included in such 2014 Annual Report on Form 10-K are the same used in preparing the accompanying unaudited condensed consolidated financial statements. Net income for interim periods may not necessarily be indicative of results for the full year.

Gas and Liquids Stored Underg22

Gas and Liquids Stored Underground and Gas and NGLs Receivables and Payables (Policies)	6 Months Ended
	Jun. 30, 2015
Gas Balancing Arrangements [Abstract]
Gas and Liquids Stored Underground and Gas and NGLs Receivables and Payables, Policy [Policy Text Block]	Gas and Liquids Stored Underground and Gas and NGLs Receivables and Payables Subsidiaries of the Partnership provide storage services whereby they store natural gas or NGLs on behalf of customers and also periodically hold customer gas under parking and lending (PAL) services. Since the customers retain title to the gas held by the Partnership in providing these services, the Partnership does not record the related gas on its balance sheet.

Fair Value Measurements and O23

Fair Value Measurements and Other Comprehensive Income (OCI) (Policies)	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments, Policy [Policy Text Block]	Financial Assets and Liabilities The following methods and assumptions were used in estimating the fair value amounts included in the disclosures for financial assets and liabilities, which are consistent with those disclosed in the 2014 Annual Report on Form 10-K: Cash and Cash Equivalents: For cash and short-term financial assets, the carrying amount is a reasonable estimate of fair value due to the short maturity of those instruments. Long-Term Debt: The estimated fair value of the Partnership's publicly traded debt is based on quoted market prices at June 30, 2015 , and December 31, 2014 . The fair market value of the debt that is not publicly traded is based on market prices of similar debt at June 30, 2015 , and December 31, 2014 . The carrying amount of the Partnership's variable-rate debt approximates fair value because the instruments bear a floating market-based interest rate.

Commitments and Contingencies E

Commitments and Contingencies Environmental Costs Policy (Policies)	6 Months Ended
	Jun. 30, 2015
Accounting Policies [Abstract]
Environmental Costs, Policy [Policy Text Block]	The liability represents management’s estimate of the undiscounted future obligations based on evaluations and discussions with counsel and operating personnel and the current facts and circumstances related to these matters.

Cash Distributions and Net In25

Cash Distributions and Net Income per Unit (Policies)	6 Months Ended
Cash Distributions and Net Income per Unit (Policies)	Jun. 30, 2015
Partners' Capital Notes [Abstract]
Net Income Per Unit, Policy [Policy Text Block]	Net Income per Unit For purposes of calculating net income per unit, net income for the current period is reduced by the amount of available cash that will be distributed with respect to that period. Payments made on account of the Partnership’s various ownership interests are determined in relation to actual declared distributions, and are not based on the assumed allocations required under GAAP. Any residual amount representing undistributed net income is assumed to be allocated to the various ownership interests in accordance with the contractual provisions of the partnership agreement on a pro rata basis. Net income per unit is calculated based on the weighted-average number of units outstanding for the period.

Fair Value Measurements and O26

Fair Value Measurements and Other Comprehensive Income (OCI) OCI (Tables)	6 Months Ended
	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following table shows the components and reclassifications to net income of AOCI which is included in Partners' Capital on the Condensed Consolidated Balance Sheets for the three months ended June 30, 2015 (in millions): Cash Flow Hedges Pension and Other Postretirement Costs Total Beginning balance, April 1, 2015 $ (10.2 ) $ (64.1 ) $ (74.3 ) Reclassifications: Interest expense 0.6 — 0.6 Pension and other postretirement benefit costs — (2.2 ) (2.2 ) Ending balance, June 30, 2015 $ (9.6 ) $ (66.3 ) $ (75.9 ) The following table shows the components and reclassifications to net income of AOCI which is included in Partners' Capital on the Condensed Consolidated Balance Sheets for the three months ended June 30, 2014 (in millions): Cash Flow Hedges Pension and Other Postretirement Costs Total Beginning balance, April 1, 2014 $ (12.7 ) $ (53.0 ) $ (65.7 ) Reclassifications: Transportation operating revenues 0.1 — 0.1 Interest expense 0.6 — 0.6 Pension and other postretirement benefit costs — (2.0 ) (2.0 ) Ending balance, June 30, 2014 $ (12.0 ) $ (55.0 ) $ (67.0 ) The following table shows the components and reclassifications to net income of AOCI which is included in Partners' Capital on the Condensed Consolidated Balance Sheets for the six months ended June 30, 2015 (in millions): Cash Flow Hedges Pension and Other Postretirement Costs Total Beginning balance, January 1, 2015 $ (10.8 ) $ (62.0 ) $ (72.8 ) Reclassifications: Interest expense 1.2 — 1.2 Pension and other postretirement benefit costs — (4.3 ) (4.3 ) Ending balance, June 30, 2015 $ (9.6 ) $ (66.3 ) $ (75.9 ) The following table shows the components and reclassifications to net income of AOCI which is included in Partners' Capital on the Condensed Consolidated Balance Sheets for the six months ended June 30, 2014 (in millions): Cash Flow Hedges Pension and Other Postretirement Costs Total Beginning balance, January 1, 2014 $ (12.7 ) $ (51.1 ) $ (63.8 ) Loss recorded in accumulated other comprehensive loss (0.9 ) — (0.9 ) Reclassifications: Transportation operating revenues 0.2 — 0.2 Other operating revenues 0.2 — 0.2 Interest expense 1.2 — 1.2 Pension and other postretirement benefit costs — (3.9 ) (3.9 ) Ending balance, June 30, 2014 $ (12.0 ) $ (55.0 ) $ (67.0 )

Fair Value Measurements and O27

Fair Value Measurements and Other Comprehensive Income (OCI) Financial Assets and Liabilities (Tables)	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value, by Balance Sheet Grouping [Table Text Block]	The carrying amount and estimated fair values of the Partnership's financial assets and liabilities which are not recorded at fair value on the Condensed Consolidated Balance Sheets as of June 30, 2015 , and December 31, 2014 , were as follows (in millions): As of June 30, 2015 Estimated Fair Value Financial Assets Carrying Amount Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 19.3 $ 19.3 $ — $ — $ 19.3 Financial Liabilities Long-term debt $ 3,484.2 (1) $ — $ 3,536.3 $ — $ 3,536.3 (1) The carrying amount of long-term debt excludes a $9.4 million capital lease obligation. As of December 31, 2014 Estimated Fair Value Financial Assets Carrying Amount Level 1 Level 2 Level 3 Total Cash and cash equivalents $ 6.6 $ 6.6 $ — $ — $ 6.6 Financial Liabilities Long-term debt $ 3,680.1 (1) $ — $ 3,787.4 $ — $ 3,787.4 (1) The carrying amount of long-term debt excludes a $9.6 million capital lease obligation.

Cash Distributions and Net In28

Cash Distributions and Net Income per Unit (Tables)	6 Months Ended
Cash Distributions and Net Income per Unit (Tables)	Jun. 30, 2015
Partners' Capital Notes [Abstract]
Distributions Made to Limited Partner, by Distribution [Table Text Block]	The following table provides a reconciliation of net income and the assumed allocation of net income to the common units for purposes of computing net income per unit for the three months ended June 30, 2015 , (in millions, except per unit data): Total Common Units General Partner and IDRs Net income $ 40.4 Declared distribution 25.6 $ 25.1 $ 0.5 Assumed allocation of undistributed net income 14.8 14.5 0.3 Assumed allocation of net income attributable to limited partner unitholders and general partner $ 40.4 $ 39.6 $ 0.8 Weighted-average units outstanding 250.3 Net income per unit $ 0.16 The following table provides a reconciliation of net income and the assumed allocation of net income to the common units for purposes of computing net income per unit for the three months ended June 30, 2014 , (in millions, except per unit data): Total Common Units General Partner and IDRs Net income $ 55.9 Less: Net loss attributable to noncontrolling interests (1.5 ) Net income attributable to controlling interests 57.4 Declared distribution 24.8 $ 24.3 $ 0.5 Assumed allocation of undistributed net income 32.6 32.0 0.6 Assumed allocation of net income attributable to limited partner unitholders and general partner $ 57.4 $ 56.3 $ 1.1 Weighted-average units outstanding 243.3 Net income per unit $ 0.23 The following table provides a reconciliation of net income and the assumed allocation of net income to the common units for purposes of computing net income per unit for the six months ended June 30, 2015 , (in millions, except per unit data): Total Common Units General Partner and IDRs Net income $ 118.1 Declared distribution 51.1 $ 50.1 $ 1.0 Assumed allocation of undistributed net income 67.0 65.7 1.3 Assumed allocation of net income attributable to limited partner unitholders and general partner $ 118.1 $ 115.8 $ 2.3 Weighted-average units outstanding 247.3 Net income per unit $ 0.47 The following table provides a reconciliation of net income and the assumed allocation of net income to the common units for purposes of computing net income per unit for the six months ended June 30, 2014 , (in millions, except per unit data): Total Common Units General Partner and IDRs Net income $ 81.5 Less: Net loss attributable to noncontrolling interests (86.1 ) Net income attributable to controlling interests 167.6 Declared distribution 49.6 $ 48.7 $ 0.9 Assumed allocation of undistributed net income 118.0 115.6 2.4 Assumed allocation of net income attributable to limited partner unitholders and general partner $ 167.6 $ 164.3 $ 3.3 Weighted-average units outstanding 243.3 Net income per unit $ 0.68

Financing (Tables)

Financing (Tables)	6 Months Ended
Financing (Tables)	Jun. 30, 2015
Debt Disclosure [Abstract]
Debt Issuances [Table Text Block]	In March 2015, the Partnership completed an additional issuance of its 4.95% senior notes due 2024 (Boardwalk Pipelines 2024 Notes), of which $350.0 million were originally issued in November 2014 (in millions, except interest rates): Date of Issuance Issuing Subsidiary Amount of Issuance Purchaser Discounts and Expenses Net Proceeds Interest Rate Maturity Date Interest Payable March 2015 Boardwalk Pipelines $ 250.0 $ 2.9 $ 247.1 (1) 4.95% December 15, 2024 June 15 and December 15 (1) The net proceeds of this offering were used to retire a portion of the outstanding $250.0 million aggregate principal amount of Texas Gas Transmission, LLC's (Texas Gas) 4.60% notes that matured in June 2015 (Texas Gas 2015 Notes). Initially, the Partnership used the net proceeds to reduce outstanding borrowings under its revolving credit facility. Subsequently, on June 1, 2015, the Partnership retired the Texas Gas 2015 Notes with borrowings under its revolving credit facility.

Employee Benefits (Tables)

Employee Benefits (Tables)	6 Months Ended
Employee Benefits (Tables)	Jun. 30, 2015
Compensation and Retirement Disclosure [Abstract]
Schedule of Net Benefit Costs [Table Text Block]	Components of net periodic benefit cost for both the Retirement Plans and PBOP for the three months ended June 30, 2015 and 2014 were as follows (in millions): Retirement Plans PBOP For the For the 2015 2014 2015 2014 Service cost $ 1.0 $ 1.0 $ 0.1 $ 0.1 Interest cost 1.2 1.4 0.5 0.6 Expected return on plan assets (2.3 ) (2.4 ) (1.1 ) (1.0 ) Amortization of prior service credit — — (1.9 ) (2.0 ) Amortization of unrecognized net loss 0.4 0.3 (0.1 ) — Regulatory asset decrease 0.5 0.5 — — Net periodic benefit cost $ 0.8 $ 0.8 $ (2.5 ) $ (2.3 ) Components of net periodic benefit cost for both the Retirement Plans and PBOP for the six months ended June 30, 2015 and 2014 were as follows (in millions): Retirement Plans PBOP For the For the 2015 2014 2015 2014 Service cost $ 2.0 $ 2.0 $ 0.2 $ 0.2 Interest cost 2.4 2.8 1.0 1.1 Expected return on plan assets (4.6 ) (4.7 ) (2.3 ) (2.1 ) Amortization of prior service credit — — (3.8 ) (3.9 ) Amortization of unrecognized net loss 0.8 0.6 — 0.1 Regulatory asset decrease 1.0 0.9 — — Net periodic benefit cost $ 1.6 $ 1.6 $ (4.9 ) $ (4.6 )

Supplemental Disclosure of Ca31

Supplemental Disclosure of Cash Flow Information (Tables)	6 Months Ended
Supplemental Disclosure of Cash Flow Information (Tables)	Jun. 30, 2015
Supplemental Cash Flow Elements [Abstract]
Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]	Supplemental Disclosure of Cash Flow Information (in millions): For the 2015 2014 Cash paid during the period for: Interest (net of amount capitalized) $ 91.4 $ 76.1

Guarantee of Securities of Su32

Guarantee of Securities of Subsidiaries (Tables)	6 Months Ended
Guarantee of Securities of Subsidiaries (Tables)	Jun. 30, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Consolidating Balance Sheet	Condensed Consolidating Balance Sheets as of June 30, 2015 (Millions) Assets Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Cash and cash equivalents $ 0.5 $ 2.8 $ 16.0 $ — $ 19.3 Receivables 0.1 — 105.5 — 105.6 Receivables - affiliate — — 6.6 (6.6 ) — Gas and liquids stored underground — — 8.5 — 8.5 Prepayments 0.2 0.1 19.5 — 19.8 Advances to affiliates — 20.4 145.2 (165.6 ) — Other current assets — — 14.0 (5.1 ) 8.9 Total current assets 0.8 23.3 315.3 (177.3 ) 162.1 Investment in consolidated subsidiaries 2,072.6 6,915.7 — (8,988.3 ) — Property, plant and equipment, gross 0.6 — 9,498.0 — 9,498.6 Less–accumulated depreciation and amortization 0.6 — 1,923.0 — 1,923.6 Property, plant and equipment, net — — 7,575.0 — 7,575.0 Other noncurrent assets — 5.4 473.6 0.1 479.1 Advances to affiliates – noncurrent 2,226.0 502.3 1,008.8 (3,737.1 ) — Total other assets 2,226.0 507.7 1,482.4 (3,737.0 ) 479.1 Total Assets $ 4,299.4 $ 7,446.7 $ 9,372.7 $ (12,902.6 ) $ 8,216.2 Liabilities and Partners' Capital Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Payables $ 0.2 $ — $ 85.8 $ — $ 86.0 Payable to affiliates 0.9 — 6.6 (6.6 ) 0.9 Advances from affiliates — 145.2 20.4 (165.6 ) — Other current liabilities — 20.9 136.5 (5.1 ) 152.3 Total current liabilities 1.1 166.1 249.3 (177.3 ) 239.2 Long-term debt and capital lease obligation — 1,973.2 1,520.4 — 3,493.6 Payable to affiliate - noncurrent 16.0 — — — 16.0 Advances from affiliates - noncurrent — 3,234.8 502.3 (3,737.1 ) — Other noncurrent liabilities — — 185.0 0.1 185.1 Total other liabilities and deferred credits 16.0 3,234.8 687.3 (3,737.0 ) 201.1 Total partners' capital 4,282.3 2,072.6 6,915.7 (8,988.3 ) 4,282.3 Total Liabilities and Partners' Capital $ 4,299.4 $ 7,446.7 $ 9,372.7 $ (12,902.6 ) $ 8,216.2 Condensed Consolidating Balance Sheets as of December 31, 2014 (Millions) Assets Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Cash and cash equivalents $ 0.5 $ 1.8 $ 4.3 $ — $ 6.6 Receivables — — 110.9 — 110.9 Receivables - affiliate — — 9.0 (9.0 ) — Gas and liquids stored underground — — 4.1 — 4.1 Prepayments 0.1 — 14.4 — 14.5 Advances to affiliates — 6.3 106.2 (112.5 ) — Other current assets 0.5 — 19.2 (6.2 ) 13.5 Total current assets 1.1 8.1 268.1 (127.7 ) 149.6 Investment in consolidated subsidiaries 1,970.6 6,744.1 — (8,714.7 ) — Property, plant and equipment, gross 0.6 — 9,355.0 — 9,355.6 Less–accumulated depreciation and amortization 0.6 — 1,765.8 — 1,766.4 Property, plant and equipment, net — — 7,589.2 — 7,589.2 Other noncurrent assets — 3.4 465.2 (0.6 ) 468.0 Advances to affiliates – noncurrent 2,148.3 212.0 996.5 (3,356.8 ) — Total other assets 2,148.3 215.4 1,461.7 (3,357.4 ) 468.0 Total Assets $ 4,120.0 $ 6,967.6 $ 9,319.0 $ (12,199.8 ) $ 8,206.8 Liabilities and Partners' Capital Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Payables $ 0.2 $ 0.1 $ 61.8 $ — $ 62.1 Payable to affiliates 1.5 — 9.0 (9.0 ) 1.5 Advances from affiliates — 106.2 6.3 (112.5 ) — Other current liabilities — 21.4 141.7 (6.5 ) 156.6 Total current liabilities 1.7 127.7 218.8 (128.0 ) 220.2 Long-term debt and capital lease obligation — 1,724.5 1,965.2 — 3,689.7 Payable to affiliate - noncurrent 16.0 — — — 16.0 Advances from affiliates - noncurrent — 3,144.8 212.0 (3,356.8 ) — Other noncurrent liabilities — — 178.9 (0.3 ) 178.6 Total other liabilities and deferred credits 16.0 3,144.8 390.9 (3,357.1 ) 194.6 Total partners' capital 4,102.3 1,970.6 6,744.1 (8,714.7 ) 4,102.3 Total Liabilities and Partners' Capital $ 4,120.0 $ 6,967.6 $ 9,319.0 $ (12,199.8 ) $ 8,206.8
Condensed Consolidating Statements of Income	Condensed Consolidating Statements of Income for the Three Months Ended June 30, 2015 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Operating Revenues: Transportation $ — $ — $ 278.6 $ (21.7 ) $ 256.9 Parking and lending — — 3.0 (0.2 ) 2.8 Storage — — 20.9 — 20.9 Other — — 18.0 — 18.0 Total operating revenues — — 320.5 (21.9 ) 298.6 Operating Costs and Expenses: Fuel and transportation — — 45.5 (21.9 ) 23.6 Operation and maintenance — — 54.6 — 54.6 Administrative and general (0.2 ) — 32.0 — 31.8 Other operating costs and expenses 0.2 — 102.5 — 102.7 Total operating costs and expenses — — 234.6 (21.9 ) 212.7 Operating income — — 85.9 — 85.9 Other Deductions (Income): Interest expense — 27.9 18.0 — 45.9 Interest (income) expense - affiliates, net (7.2 ) 9.1 (1.9 ) — — Interest income — — (0.1 ) — (0.1 ) Equity in earnings of subsidiaries (33.2 ) (70.2 ) — 103.4 — Miscellaneous other income, net — — (0.4 ) — (0.4 ) Total other (income) deductions (40.4 ) (33.2 ) 15.6 103.4 45.4 Income (loss) before income taxes 40.4 33.2 70.3 (103.4 ) 40.5 Income taxes — — 0.1 — 0.1 Net income (loss) $ 40.4 $ 33.2 $ 70.2 $ (103.4 ) $ 40.4 Condensed Consolidating Statements of Income for the Three Months Ended June 30, 2014 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Operating Revenues: Transportation $ — $ — $ 268.5 $ (22.8 ) $ 245.7 Parking and lending — — 9.2 — 9.2 Storage — — 22.2 (0.1 ) 22.1 Other — — 16.4 — 16.4 Total operating revenues — — 316.3 (22.9 ) 293.4 Operating Costs and Expenses: Fuel and transportation — — 52.8 (22.9 ) 29.9 Operation and maintenance — — 43.9 — 43.9 Administrative and general — — 30.5 — 30.5 Other operating costs and expenses — — 92.6 — 92.6 Total operating costs and expenses — — 219.8 (22.9 ) 196.9 Operating income — — 96.5 — 96.5 Other Deductions (Income): Interest expense — 18.7 21.5 — 40.2 Interest (income) expense - affiliates, net (7.6 ) 10.2 (2.6 ) — — Interest income — — (0.2 ) — (0.2 ) Equity in earnings of subsidiaries (49.8 ) (78.7 ) — 128.5 — Equity losses in unconsolidated affiliates — — 0.5 — 0.5 Total other (income) deductions (57.4 ) (49.8 ) 19.2 128.5 40.5 Income (loss) before income taxes 57.4 49.8 77.3 (128.5 ) 56.0 Income taxes — — 0.1 — 0.1 Net income (loss) 57.4 49.8 77.2 (128.5 ) 55.9 Net loss attributable to noncontrolling interests — — (1.5 ) — (1.5 ) Net income (loss) attributable to controlling interests $ 57.4 $ 49.8 $ 78.7 $ (128.5 ) $ 57.4 Condensed Consolidating Statements of Income for the Six Months Ended June 30, 2015 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Operating Revenues: Transportation $ — $ — $ 590.2 $ (43.7 ) $ 546.5 Parking and lending — — 5.8 (0.2 ) 5.6 Storage — — 40.2 — 40.2 Other — — 36.0 — 36.0 Total operating revenues — — 672.2 (43.9 ) 628.3 Operating Costs and Expenses: Fuel and transportation — — 94.5 (43.9 ) 50.6 Operation and maintenance — — 97.0 — 97.0 Administrative and general (0.2 ) — 62.6 — 62.4 Other operating costs and expenses 0.2 — 209.4 — 209.6 Total operating costs and expenses — — 463.5 (43.9 ) 419.6 Operating income — — 208.7 — 208.7 Other Deductions (Income): Interest expense — 51.8 39.3 — 91.1 Interest (income) expense - affiliates, net (13.9 ) 18.6 (4.7 ) — — Interest income — — (0.2 ) — (0.2 ) Equity in earnings of subsidiaries (104.2 ) (174.6 ) — 278.8 — Miscellaneous other income, net — — (0.6 ) — (0.6 ) Total other (income) deductions (118.1 ) (104.2 ) 33.8 278.8 90.3 Income (loss) before income taxes 118.1 104.2 174.9 (278.8 ) 118.4 Income taxes — — 0.3 — 0.3 Net income (loss) $ 118.1 $ 104.2 $ 174.6 $ (278.8 ) $ 118.1 Condensed Consolidating Statements of Income for the Six Months Ended June 30, 2014 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Operating Revenues: Transportation $ — $ — $ 595.6 $ (45.6 ) $ 550.0 Parking and lending — — 18.4 — 18.4 Storage — — 51.0 (0.1 ) 50.9 Other — — 31.0 — 31.0 Total operating revenues — — 696.0 (45.7 ) 650.3 Operating Costs and Expenses: Fuel and transportation — — 108.6 (45.7 ) 62.9 Operation and maintenance — — 86.6 — 86.6 Administrative and general (0.1 ) — 57.4 — 57.3 Other operating costs and expenses 0.1 — 194.3 — 194.4 Total operating costs and expenses — — 446.9 (45.7 ) 401.2 Operating income — — 249.1 — 249.1 Other Deductions (Income): Interest expense — 37.4 43.7 — 81.1 Interest (income) expense - affiliates, net (15.4 ) 20.4 (5.0 ) — — Interest income — — (0.3 ) — (0.3 ) Equity in earnings of subsidiaries (152.2 ) (210.0 ) — 362.2 — Equity losses in unconsolidated affiliates — — 86.6 — 86.6 Miscellaneous other income, net — — (0.1 ) — (0.1 ) Total other (income) deductions (167.6 ) (152.2 ) 124.9 362.2 167.3 Income (loss) before income taxes 167.6 152.2 124.2 (362.2 ) 81.8 Income taxes — — 0.3 — 0.3 Net income (loss) 167.6 152.2 123.9 (362.2 ) 81.5 Net loss attributable to noncontrolling interests — — (86.1 ) — (86.1 ) Net income (loss) attributable to controlling interests $ 167.6 $ 152.2 $ 210.0 $ (362.2 ) $ 167.6
Condensed Consolidating Statements Of Comprehensive Income	Condensed Consolidating Statements of Comprehensive Income for the Three Months Ended June 30, 2015 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Net income (loss) $ 40.4 $ 33.2 $ 70.2 $ (103.4 ) $ 40.4 Other comprehensive income (loss): Reclassification adjustment transferred to Net Income from cash flow hedges 0.6 0.6 0.2 (0.8 ) 0.6 Pension and other postretirement benefit costs (2.2 ) (2.2 ) (2.2 ) 4.4 (2.2 ) Total Comprehensive Income (Loss) $ 38.8 $ 31.6 $ 68.2 $ (99.8 ) $ 38.8 Condensed Consolidating Statements of Comprehensive Income for the Three Months Ended June 30, 2014 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Net income (loss) $ 57.4 $ 49.8 $ 77.2 $ (128.5 ) $ 55.9 Other comprehensive income (loss) : Reclassification adjustment transferred to Net Income from cash flow hedges 0.7 0.7 0.3 (1.0 ) 0.7 Pension and other postretirement benefit costs (2.0 ) (2.0 ) (2.0 ) 4.0 (2.0 ) Total Comprehensive Income (Loss) 56.1 48.5 75.5 (125.5 ) 54.6 Comprehensive loss attributable to noncontrolling interests — — (1.5 ) — (1.5 ) Comprehensive income (loss) attributable to controlling interests $ 56.1 $ 48.5 $ 77.0 $ (125.5 ) $ 56.1 Condensed Consolidating Statements of Comprehensive Income for the Six Months Ended June 30, 2015 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Net income (loss) $ 118.1 $ 104.2 $ 174.6 $ (278.8 ) $ 118.1 Other comprehensive income (loss): Reclassification adjustment transferred to Net Income from cash flow hedges 1.2 1.2 0.4 (1.6 ) 1.2 Pension and other postretirement benefit costs (4.3 ) (4.3 ) (4.3 ) 8.6 (4.3 ) Total Comprehensive Income (Loss) $ 115.0 $ 101.1 $ 170.7 $ (271.8 ) $ 115.0 Condensed Consolidating Statements of Comprehensive Income for the Six Months Ended June 30, 2014 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Net income (loss) $ 167.6 $ 152.2 $ 123.9 $ (362.2 ) $ 81.5 Other comprehensive income (loss): (Loss) gain on cash flow hedges (0.9 ) (0.9 ) (0.9 ) 1.8 (0.9 ) Reclassification adjustment transferred to Net Income from cash flow hedges 1.6 1.6 0.8 (2.4 ) 1.6 Pension and other postretirement benefit costs (3.9 ) (3.9 ) (3.9 ) 7.8 (3.9 ) Total Comprehensive Income (Loss) 164.4 149.0 119.9 (355.0 ) 78.3 Comprehensive loss attributable to noncontrolling interests — — (86.1 ) — (86.1 ) Comprehensive income (loss) attributable to controlling interests $ 164.4 $ 149.0 $ 206.0 $ (355.0 ) $ 164.4
Condensed Consolidating Statements of Cash Flows	Condensed Consolidating Statements of Cash Flow for the Six Months Ended June 30, 2015 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Net cash provided by (used in) operating activities $ 12.6 $ (67.1 ) $ 340.0 $ — $ 285.5 INVESTING ACTIVITIES: Capital expenditures — — (136.3 ) — (136.3 ) Proceeds from sale of operating assets — — 0.1 — 0.1 Advances to affiliates, net (77.7 ) (304.4 ) (51.3 ) 433.4 — Net cash (used in) provided by investing activities (77.7 ) (304.4 ) (187.5 ) 433.4 (136.2 ) FINANCING ACTIVITIES: Proceeds from long-term debt — 247.1 — — 247.1 Repayment of borrowings from long-term debt and term loan — — (725.0 ) — (725.0 ) Proceeds from borrowings on revolving credit agreement — — 835.0 — 835.0 Repayment of borrowings on revolving credit agreement, including financing fees — (3.6 ) (555.0 ) — (558.6 ) Principal payment of capital lease obligation — — (0.2 ) — (0.2 ) Advances from affiliates, net 0.1 129.0 304.4 (433.4 ) 0.1 Distributions paid (50.4 ) — — — (50.4 ) Proceeds from sale of common units 113.1 — — — 113.1 Capital contributions from general partner 2.3 — — — 2.3 Net cash provided by (used in) financing activities 65.1 — 372.5 — (140.8 ) — (433.4 ) — (136.6 ) Increase in cash and cash equivalents — 1.0 11.7 — 12.7 Cash and cash equivalents at beginning of period 0.5 1.8 4.3 — 6.6 Cash and cash equivalents at end of period $ 0.5 $ 2.8 $ 16.0 $ — $ 19.3 Condensed Consolidating Statements of Cash Flow for the Six Months Ended June 30, 2014 (Millions) Parent Guarantor Subsidiary Issuer Non-guarantor Subsidiaries Eliminations Consolidated Boardwalk Pipeline Partners, LP Net cash provided by (used in) operating activities $ 15.5 $ (55.8 ) $ 348.4 $ — $ 308.1 INVESTING ACTIVITIES: Capital expenditures — — (162.7 ) — (162.7 ) Proceeds from sale of operating assets — — 2.9 — 2.9 Advances to affiliates, net 33.8 (16.6 ) (98.8 ) 81.7 0.1 Investment in unconsolidated affiliates — — (20.3 ) — (20.3 ) Distributions from unconsolidated affiliates — — 10.7 — 10.7 Net cash provided by (used in) investing activities 33.8 (16.6 ) (268.2 ) 81.7 (169.3 ) FINANCING ACTIVITIES: Proceeds from borrowings on revolving credit agreement — — 220.0 — 220.0 Repayment of borrowings on revolving credit agreement — — (295.0 ) — (295.0 ) Principal payment of capital lease obligation — — (0.2 ) — (0.2 ) Advances from affiliates, net 0.1 65.1 16.6 (81.7 ) 0.1 Distributions paid (49.6 ) — — — (49.6 ) Capital contributions from noncontrolling interests — — 7.8 — 7.8 Distributions paid to noncontrolling interests — — (7.1 ) — (7.1 ) Net cash (used in) provided by financing activities (49.5 ) 65.1 (57.9 ) (81.7 ) (124.0 ) (Decrease) increase in cash and cash equivalents (0.2 ) (7.3 ) 22.3 — 14.8 Cash and cash equivalents at beginning of period 0.2 9.2 19.1 — 28.5 Cash and cash equivalents at end of period $ — $ 1.9 $ 41.4 $ — $ 43.3

Basis of Presentation (Details)

Basis of Presentation (Details) - shares shares in Millions	Aug. 03, 2015	Jun. 30, 2015	Jun. 30, 2014
Boardwalk Pipelines Holding Company \| Subsequent Event
Number Of Partnerships Common Units Owned By Holding Company	125.6
Percentage of Partnership's equity interests owned by holding company (in hundredths)	51.00%
Boardwalk GP, LP
Percent of general partner interest owned by holding company		2.00%	2.00%
Boardwalk GP, LP \| Subsequent Event
Percent of general partner interest owned by holding company	2.00%

Gas and Liquids Stored Underg34

Gas and Liquids Stored Underground and Gas and NGLs Receivables and Payables (Details) MMBTU in Millions, $ in Millions	Jun. 30, 2015USD ($)$ / MMBTUMMBTUMMBbls	Dec. 31, 2014MMBTUMMBbls
Gas Balancing Arrangements [Abstract]
Gas Balancing Volume Amount (MMBtu in millions) \| MMBTU	17.2	10
Average market price per million British thermal units \| $ / MMBTU	2.70
Market value of gas owed to operating subsidiaries due to gas imbalances and gas loaned under PAL and no-notice services	$ 46.4
Natural Gas Liquids Balancing Volume (in MMBbls) \| MMBbls	0.3	0.1
Natural Gas Liquids Imbalance to Subsidiaries Asset Liability	$ 9.4

Fair Value Measurements and O35

Fair Value Measurements and Other Comprehensive Income (OCI) Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis (Details) - Fair Value, Measurements, Nonrecurring [Member] $ in Millions	3 Months Ended
	Mar. 31, 2014USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Project Related Impairment	$ 92.9
Income (Loss) from Impairment Attributable to Noncontrolling Interest	(82.9)
Income (Loss) from Impairments Attributable to Parent	$ (10)

Fair Value Measurements and O36

Fair Value Measurements and Other Comprehensive Income (OCI) OCI (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning balance	$ (74.3)	$ (65.7)	$ (72.8)	$ (63.8)
Loss on cash flow hedges	0	0	0	(0.9)
Transportation operating revenues	256.9	245.7	546.5	550
Interest expense	45.9	40.2	91.1	81.1
Pension and other postretirement benefit costs	(2.2)	(2)	(4.3)	(3.9)
Ending balance	(75.9)	(67)	(75.9)	(67)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Transportation operating revenues		0.1		0.2
Other operating revenues				0.2
Interest expense	0.6	0.6	1.2	1.2
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months			(2.4)
Beginning balance	(10.2)	(12.7)	(10.8)	(12.7)
Loss on cash flow hedges				(0.9)
Pension and other postretirement benefit costs	0	0	0	0
Ending balance	(9.6)	(12)	(9.6)	(12)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges \| Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Transportation operating revenues		0.1		0.2
Other operating revenues				0.2
Interest expense	0.6	0.6	1.2	1.2
Accumulated Defined Benefit Plans Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Beginning balance	(64.1)	(53)	(62)	(51.1)
Loss on cash flow hedges				0
Pension and other postretirement benefit costs	(2.2)	(2)	(4.3)	(3.9)
Ending balance	(66.3)	(55)	(66.3)	(55)
Accumulated Defined Benefit Plans Adjustment \| Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Transportation operating revenues		0		0
Other operating revenues				0
Interest expense	$ 0	$ 0	$ 0	$ 0

Fair Value Measurements and O37

Fair Value Measurements and Other Comprehensive Income (OCI) Financial Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2015		Dec. 31, 2014		Jun. 30, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 19.3		$ 6.6		$ 43.3	$ 28.5
Capital Lease Obligations, Noncurrent	9.4		9.6
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and Cash Equivalents - Fair Value	19.3		6.6
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term Debt - Fair Value	3,536.3		3,787.4
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	19.3		6.6
Long-term Debt	3,484.2	[1]	3,680.1	[2]
Fair Value \| Fair Value, Inputs, Level 1
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and Cash Equivalents - Fair Value	19.3		6.6
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term Debt - Fair Value	0		0
Fair Value \| Fair Value, Inputs, Level 2
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and Cash Equivalents - Fair Value	0		0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term Debt - Fair Value	3,536.3		3,787.4
Fair Value \| Fair Value, Inputs, Level 3
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and Cash Equivalents - Fair Value	0		0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term Debt - Fair Value	$ 0		$ 0

[1]	The carrying amount of long-term debt excludes a $9.4 million capital lease obligation.
[2]	The carrying amount of long-term debt excludes a $9.6 million capital lease obligation.

Property, Plant and Equipment (

Property, Plant and Equipment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Text Block [Abstract]
Asset impairment	$ 0	$ 1.4	$ 0.1	$ 8.6

Commitments and Contingencies L

Commitments and Contingencies Legal Proceedings and Settlements (Details) $ in Millions	Aug. 03, 2015USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2015USD ($)defendant
Loss Contingencies [Line Items]
Rate Case Incremental Revenues		$ 5.7
Gain on Business Interruption Insurance Recovery		$ 6.3	$ 6.3
Southeast Louisiana Flood Protection Litigation
Loss Contingencies [Line Items]
Loss Contingency, Number of Defendants \| defendant			100
Subsequent Event
Loss Contingencies [Line Items]
Gain on Business Interruption Insurance Recovery	$ 2.5

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Environmental and Safety Matters [Abstract]
Accrual for Environmental Loss Contingencies	$ 5.2	$ 6.1
Number of years the related expenditures are expected to cover assessment and remediation costs (in years)	7 years
Accrued Environmental Loss Contingencies, Current	$ 1.5	1.5
Accrued Environmental Loss Contingencies, Noncurrent	3.7	$ 4.6
Commitments for Construction [Abstract]
Purchase Commitment, Remaining Minimum Amount Committed	$ 155.1

Cash Distributions and Net In41

Cash Distributions and Net Income per Unit (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Aug. 03, 2015	Jul. 30, 2015
Reconciliation And Allocation of Net Income By Class of Stock [Line Items]
Net Income	$ 40.4	$ 55.9	$ 118.1	$ 81.5
Less: Net loss attributable to noncontrolling interests	0	(1.5)	0	(86.1)
Net income attributable to controlling interests	40.4	57.4	118.1	167.6
Declared distribution	25.6	24.8	51.1	49.6
Assumed allocation of undistributed net income	14.8	32.6	67	118
Assumed allocation of net income attributable to limited partner unitholders and general partner	40.4	57.4	118.1	167.6
Common Units
Reconciliation And Allocation of Net Income By Class of Stock [Line Items]
Declared distribution	25.1	24.3	50.1	48.7
Assumed allocation of undistributed net income	14.5	32	65.7	115.6
Assumed allocation of net income attributable to limited partner unitholders and general partner	$ 39.6	$ 56.3	$ 115.8	$ 164.3
Weighted-average number of units outstanding (in units)	250.3	243.3	247.3	243.3
Net income per common unit (in units)	$ 0.16	$ 0.23	$ 0.47	$ 0.68
General Partner and IDRs
Reconciliation And Allocation of Net Income By Class of Stock [Line Items]
Declared distribution	$ 0.5	$ 0.5	$ 1	$ 0.9
Assumed allocation of undistributed net income	0.3	0.6	1.3	2.4
Assumed allocation of net income attributable to limited partner unitholders and general partner	$ 0.8	$ 1.1	$ 2.3	$ 3.3
Common Units
Reconciliation And Allocation of Net Income By Class of Stock [Line Items]
Cash distribution declared and paid to common units (in units)	$ 0.10	$ 0.10	$ 0.20	$ 0.20
Weighted-average number of units outstanding (in units)	250.3	243.3	247.3	243.3
Net income per common unit (in units)	$ 0.16	$ 0.23	$ 0.47	$ 0.68
Common Units \| Subsequent Event
Reconciliation And Allocation of Net Income By Class of Stock [Line Items]
Dividends Payable, Amount Per Share						$ 0.10
Boardwalk GP, LP
Reconciliation And Allocation of Net Income By Class of Stock [Line Items]
Percent of general partner interest owned by holding company	2.00%	2.00%	2.00%	2.00%
Boardwalk GP, LP \| Subsequent Event
Reconciliation And Allocation of Net Income By Class of Stock [Line Items]
Percent of general partner interest owned by holding company					2.00%

Financing - Debt (Details)

Financing - Debt (Details) - USD ($) $ in Millions	Jun. 01, 2015	Mar. 10, 2015	Feb. 02, 2015	Nov. 19, 2014	Jun. 30, 2015	Jun. 30, 2014	Aug. 03, 2015	Dec. 31, 2014
Debt Instruments [Abstract]
Repayments of Unsecured Debt					$ 725	$ 0
Unsecured Debt
Debt Instruments [Abstract]
Long-term Debt, Gross					$ 3,100			$ 3,400
Debt, Weighted Average Interest Rate					5.32%			5.31%
Debt Instrument, Covenant Compliance					The Partnership and its subsidiaries were in compliance with their debt covenants.
Subordinated Debt
Debt Instruments [Abstract]
Debt Instrument, Maturity Date					Jul. 31, 2024
Subordinated Loan Agreement Maximum Borrowing Capacity					$ 300
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum					5.75%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum					9.75%
Subordinated Borrowing Terms and Conditions					The Subordinated Loan bears interest at increasing rates, ranging from 5.75% to 9.75%, payable semi-annually in June and December, and matures in July 2024.
Line of Credit
Debt Instruments [Abstract]
Debt, Weighted Average Interest Rate					1.44%			1.54%
Line of Credit Facility [Abstract]
Long-term Line of Credit					$ 400			$ 120
Covenant terms					a ratio of total consolidated debt to consolidated EBITDA (as defined in the credit agreement) measured for the previous twelve months of not more than 5.0 to 1.0, or up to 5.5 to 1.0 for the three quarters following the quarter of an acquisition.
Line of Credit Facility, Covenant Compliance					The Partnership and its subsidiaries were in compliance with all covenant requirements under the credit facility.
Maximum Ratio of Debt to EBITDA					5.0 to 1.0
Maximum Ratio of Debt to EBITDA after an Acquisition					5.5 to 1.0
Line of Credit \| Subsequent Event
Line of Credit Facility [Abstract]
Long-term Line of Credit							$ 400
Line of Credit Facility, Remaining Borrowing Capacity							$ 1,100
Boardwalk Pipelines 4.95% Notes Due 2024 \| Unsecured Debt
Debt Instruments [Abstract]
Debt Instrument, Issuance Date		Mar. 10, 2015		Nov. 19, 2014
Debt Instrument, Face Amount		$ 250		$ 350
Payments of Debt Issuance Costs		2.9
Proceeds from Debt, Net of Issuance Costs		$ 247.1
Debt Instrument, Interest Rate, Stated Percentage		4.95%		4.95%
Debt Instrument, Maturity Date		Dec. 15, 2024
Gulf South Notes Due 2015 \| Unsecured Debt
Debt Instruments [Abstract]
Debt Instrument, Interest Rate, Stated Percentage			5.05%
Repayments of Unsecured Debt			$ 275
Texas Gas Notes Due 2015 \| Unsecured Debt
Debt Instruments [Abstract]
Debt Instrument, Interest Rate, Stated Percentage	4.60%
Repayments of Unsecured Debt	$ 250
Term Loan Boardwalk Acquisition Company \| Unsecured Debt
Debt Instruments [Abstract]
Long-term Debt, Gross					$ 0			$ 200
Debt, Weighted Average Interest Rate								1.91%
Debt Instrument, Maturity Date					Oct. 1, 2017
Amended Credit Agreement 2015 \| Base Rate
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis					base rate
Amended Credit Agreement 2015 \| Prime Rate
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis					prime rate
Amended Credit Agreement 2015 \| Federal Funds Effective Swap Rate
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis					federal funds
Amended Credit Agreement 2015 \| Eurodollar
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis					one month Eurodollar Rate
Amended Credit Agreement 2015 \| London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Abstract]
Debt Instrument, Description of Variable Rate Basis					LIBOR
Amended Credit Agreement 2015 \| Line of Credit
Line of Credit Facility [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity					$ 1,500
Line of Credit Facility, Expiration Date					May 26, 2020
Amended Credit Agreement 2015 \| Line of Credit \| Federal Funds Effective Swap Rate
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate					0.50%
Amended Credit Agreement 2015 \| Line of Credit \| Eurodollar
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate					1.00%
Amended Credit Agreement 2015 \| Line of Credit \| Minimum
Line of Credit Facility [Abstract]
Line of Credit Facility, Commitment Fee Percentage					0.10%
Amended Credit Agreement 2015 \| Line of Credit \| Minimum \| Base Rate
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate					0.00%
Amended Credit Agreement 2015 \| Line of Credit \| Minimum \| London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate					1.00%
Amended Credit Agreement 2015 \| Line of Credit \| Maximum
Line of Credit Facility [Abstract]
Line of Credit Facility, Commitment Fee Percentage					0.275%
Amended Credit Agreement 2015 \| Line of Credit \| Maximum \| Base Rate
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate					0.75%
Amended Credit Agreement 2015 \| Line of Credit \| Maximum \| London Interbank Offered Rate (LIBOR)
Line of Credit Facility [Abstract]
Debt Instrument, Basis Spread on Variable Rate					1.75%

Financing - Equity (Details)

Financing - Equity (Details) - USD ($) shares in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2015	Aug. 03, 2015	Jun. 30, 2014
Equity Distribution Agreement
Capital Unit [Line Items]
Limited Partners Capital Account Units Authorized Dollars	$ 500
Partners' Capital Account, Units, Sold in Public Offering	7
Proceeds from Issuance or Sale of Equity	$ 115.4
General Partners' Contributed Capital	$ 2.3
Boardwalk GP, LP
Capital Unit [Line Items]
Percent of general partner interest owned by holding company	2.00%		2.00%
Boardwalk GP, LP \| Equity Distribution Agreement
Capital Unit [Line Items]
Percent of general partner interest owned by holding company	2.00%
Subsequent Event \| Boardwalk GP, LP
Capital Unit [Line Items]
Percent of general partner interest owned by holding company		2.00%

Employee Benefits (Details)

Employee Benefits (Details) - USD ($) $ in Millions	Aug. 03, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Aug. 03, 2015
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Defined Contribution Plan, Cost Recognized		$ 2.4	$ 2.3	$ 4.6	$ 4.4
Retirement Plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1	1	2	2
Interest cost		1.2	1.4	2.4	2.8
Expected return on plan assets		(2.3)	(2.4)	(4.6)	(4.7)
Amortization of prior service credit		0	0	0	0
Amortization of unrecognized net loss		0.4	0.3	0.8	0.6
Regulatory asset decrease		0.5	0.5	1	0.9
Net periodic benefit cost		0.8	0.8	1.6	1.6
PBOP
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		0.1	0.1	0.2	0.2
Interest cost		0.5	0.6	1	1.1
Expected return on plan assets		(1.1)	(1)	(2.3)	(2.1)
Amortization of prior service credit		(1.9)	(2)	(3.8)	(3.9)
Amortization of unrecognized net loss		(0.1)	0	0	0.1
Regulatory asset decrease		0	0	0	0
Net periodic benefit cost		$ (2.5)	$ (2.3)	$ (4.9)	$ (4.6)
Subsequent Event
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Contribution to defined benefit pension plan						$ 0
Scenario, Forecast \| Subsequent Event
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Defined benefit plan, estimated future employer contributions in current fiscal year	$ 3

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	$ 2.2	$ 2.2	$ 4.4	$ 4.4
Distributions from unconsolidated affiliates			0	10.7
Payments of Ordinary Dividends, Noncontrolling Interest			$ 0	$ 7.1
Boardwalk GP, LP
Related Party Transaction [Line Items]
Percent of general partner interest owned by holding company	2.00%	2.00%	2.00%	2.00%
Cash dividends paid to parent company	$ 13.1	$ 13	$ 26.1	$ 26
Boardwalk Pipeline Partners, LP [Member] \| Boardwalk Bluegrass and Boardwalk Moss Lake [Member]
Related Party Transaction [Line Items]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures		12.7		12.7
Boardwalk Pipeline Partners, LP [Member] \| Boardwalk Moss Lake [Member]
Related Party Transaction [Line Items]
Distributions from unconsolidated affiliates				1.9
Boardwalk Pipelines Holding Company \| Boardwalk Bluegrass and Boardwalk Moss Lake [Member]
Related Party Transaction [Line Items]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures		$ 97.8		97.8
Boardwalk Pipelines Holding Company \| Boardwalk Moss Lake [Member]
Related Party Transaction [Line Items]
Payments of Ordinary Dividends, Noncontrolling Interest				$ 7.1

Supplemental Disclosure of Ca46

Supplemental Disclosure of Cash Flow Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash paid during the period for:
Interest (net of amount capitalized)	$ 91.4	$ 76.1

Guarantee of Securities of Su47

Guarantee of Securities of Subsidiaries Balance Sheets (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Restriction to Transfer Funds	Boardwalk Pipelines (subsidiary issuer) has issued securities which have been fully and unconditionally guaranteed by the Partnership (parent guarantor). The Partnership's subsidiaries have no significant restrictions on their ability to pay distributions or make loans to the Partnership except as noted in the debt covenants and have no restricted assets at June 30, 2015.	Boardwalk Pipelines (subsidiary issuer) has issued securities which have been fully and unconditionally guaranteed by the Partnership (parent guarantor). The Partnership's subsidiaries have no significant restrictions on their ability to pay distributions or make loans to the Partnership except as noted in the debt covenants and have no restricted assets at December 31, 2014.
Assets
Cash and cash equivalents	$ 19.3	$ 6.6	$ 43.3	$ 28.5
Receivables	105.6	110.9
Receivables - affiliate	0	0
Gas and liquids stored underground	8.5	4.1
Prepayments	19.8	14.5
Advances to affiliates	0	0
Other current assets	8.9	13.5
Total current assets	162.1	149.6
Investment in consolidated subsidiaries	0	0
Property, plant and equipment, gross	9,498.6	9,355.6
Less—accumulated depreciation and amortization	1,923.6	1,766.4
Property, plant and equipment, net	7,575	7,589.2
Other noncurrent assets	479.1	468
Advances to affiliates - noncurrent	0	0
Total other assets	479.1	468
Total Assets	8,216.2	8,206.8
Liabilities and Partners' Capital
Payables	86	62.1
Payable to affiliates	0.9	1.5
Advances from affiliates	0	0
Other current liabilities	152.3	156.6
Total current liabilities	239.2	220.2
Long-term debt and capital lease obligation	3,493.6	3,689.7
Payable to affiliate - noncurrent	16	16
Advances from affiliates - noncurrent	0	0
Other noncurrent liabilities	185.1	178.6
Total other liabilities and deferred credits	201.1	194.6
Total partners' capital	4,282.3	4,102.3
Total Liabilities and Partners' Capital	8,216.2	8,206.8
Eliminations
Assets
Cash and cash equivalents	0	0	0	0
Receivables	0	0
Receivables - affiliate	(6.6)	(9)
Gas and liquids stored underground	0	0
Prepayments	0	0
Advances to affiliates	(165.6)	(112.5)
Other current assets	(5.1)	(6.2)
Total current assets	(177.3)	(127.7)
Investment in consolidated subsidiaries	(8,988.3)	(8,714.7)
Property, plant and equipment, gross	0	0
Less—accumulated depreciation and amortization	0	0
Property, plant and equipment, net	0	0
Other noncurrent assets	0.1	(0.6)
Advances to affiliates - noncurrent	(3,737.1)	(3,356.8)
Total other assets	(3,737)	(3,357.4)
Total Assets	(12,902.6)	(12,199.8)
Liabilities and Partners' Capital
Payables	0	0
Payable to affiliates	(6.6)	(9)
Advances from affiliates	(165.6)	(112.5)
Other current liabilities	(5.1)	(6.5)
Total current liabilities	(177.3)	(128)
Long-term debt and capital lease obligation	0	0
Payable to affiliate - noncurrent	0	0
Advances from affiliates - noncurrent	(3,737.1)	(3,356.8)
Other noncurrent liabilities	0.1	(0.3)
Total other liabilities and deferred credits	(3,737)	(3,357.1)
Total partners' capital	(8,988.3)	(8,714.7)
Total Liabilities and Partners' Capital	(12,902.6)	(12,199.8)
Parent Guarantor \| Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	0.5	0.5	0	0.2
Receivables	0.1	0
Receivables - affiliate	0	0
Gas and liquids stored underground	0	0
Prepayments	0.2	0.1
Advances to affiliates	0	0
Other current assets	0	0.5
Total current assets	0.8	1.1
Investment in consolidated subsidiaries	2,072.6	1,970.6
Property, plant and equipment, gross	0.6	0.6
Less—accumulated depreciation and amortization	0.6	0.6
Property, plant and equipment, net	0	0
Other noncurrent assets	0	0
Advances to affiliates - noncurrent	2,226	2,148.3
Total other assets	2,226	2,148.3
Total Assets	4,299.4	4,120
Liabilities and Partners' Capital
Payables	0.2	0.2
Payable to affiliates	0.9	1.5
Advances from affiliates	0	0
Other current liabilities	0	0
Total current liabilities	1.1	1.7
Long-term debt and capital lease obligation	0	0
Payable to affiliate - noncurrent	16	16
Advances from affiliates - noncurrent	0	0
Other noncurrent liabilities	0	0
Total other liabilities and deferred credits	16	16
Total partners' capital	4,282.3	4,102.3
Total Liabilities and Partners' Capital	4,299.4	4,120
Subsidiary Issuer \| Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	2.8	1.8	1.9	9.2
Receivables	0	0
Receivables - affiliate	0	0
Gas and liquids stored underground	0	0
Prepayments	0.1	0
Advances to affiliates	20.4	6.3
Other current assets	0	0
Total current assets	23.3	8.1
Investment in consolidated subsidiaries	6,915.7	6,744.1
Property, plant and equipment, gross	0	0
Less—accumulated depreciation and amortization	0	0
Property, plant and equipment, net	0	0
Other noncurrent assets	5.4	3.4
Advances to affiliates - noncurrent	502.3	212
Total other assets	507.7	215.4
Total Assets	7,446.7	6,967.6
Liabilities and Partners' Capital
Payables	0	0.1
Payable to affiliates	0	0
Advances from affiliates	145.2	106.2
Other current liabilities	20.9	21.4
Total current liabilities	166.1	127.7
Long-term debt and capital lease obligation	1,973.2	1,724.5
Payable to affiliate - noncurrent	0	0
Advances from affiliates - noncurrent	3,234.8	3,144.8
Other noncurrent liabilities	0	0
Total other liabilities and deferred credits	3,234.8	3,144.8
Total partners' capital	2,072.6	1,970.6
Total Liabilities and Partners' Capital	7,446.7	6,967.6
Non-Guarantor Subsidiaries \| Reportable Legal Entities [Member]
Assets
Cash and cash equivalents	16	4.3	$ 41.4	$ 19.1
Receivables	105.5	110.9
Receivables - affiliate	6.6	9
Gas and liquids stored underground	8.5	4.1
Prepayments	19.5	14.4
Advances to affiliates	145.2	106.2
Other current assets	14	19.2
Total current assets	315.3	268.1
Investment in consolidated subsidiaries	0	0
Property, plant and equipment, gross	9,498	9,355
Less—accumulated depreciation and amortization	1,923	1,765.8
Property, plant and equipment, net	7,575	7,589.2
Other noncurrent assets	473.6	465.2
Advances to affiliates - noncurrent	1,008.8	996.5
Total other assets	1,482.4	1,461.7
Total Assets	9,372.7	9,319
Liabilities and Partners' Capital
Payables	85.8	61.8
Payable to affiliates	6.6	9
Advances from affiliates	20.4	6.3
Other current liabilities	136.5	141.7
Total current liabilities	249.3	218.8
Long-term debt and capital lease obligation	1,520.4	1,965.2
Payable to affiliate - noncurrent	0	0
Advances from affiliates - noncurrent	502.3	212
Other noncurrent liabilities	185	178.9
Total other liabilities and deferred credits	687.3	390.9
Total partners' capital	6,915.7	6,744.1
Total Liabilities and Partners' Capital	$ 9,372.7	$ 9,319

Guarantee of Securities of Su48

Guarantee of Securities of Subsidiaries Guarantee of Securities of Subsidiaries Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating Revenues:
Transportation	$ 256.9	$ 245.7	$ 546.5	$ 550
Parking and lending	2.8	9.2	5.6	18.4
Storage	20.9	22.1	40.2	50.9
Other	18	16.4	36	31
Total operating revenues	298.6	293.4	628.3	650.3
Operating Costs and Expenses:
Fuel and transportation	23.6	29.9	50.6	62.9
Operation and maintenance	54.6	43.9	97	86.6
Administrative and general	31.8	30.5	62.4	57.3
Other operating costs and expenses	102.7	92.6	209.6	194.4
Total operating costs and expenses	212.7	196.9	419.6	401.2
Operating income	85.9	96.5	208.7	249.1
Other Deductions (Income):
Interest expense	45.9	40.2	91.1	81.1
Interest expense - affiliates	0	0	0	0
Interest income	(0.1)	(0.2)	(0.2)	(0.3)
Equity in earnings of subsidiaries	0	0	0	0
Equity losses in unconsolidated affiliates	0	0.5	0	86.6
Miscellaneous other income, net	(0.4)	0	(0.6)	(0.1)
Total other deductions	45.4	40.5	90.3	167.3
Income (loss) before income taxes	40.5	56	118.4	81.8
Income taxes	0.1	0.1	0.3	0.3
Net income (loss)	40.4	55.9	118.1	81.5
Net loss attributable to noncontrolling interests	0	(1.5)	0	(86.1)
Net income (loss) attributable to controlling interests	40.4	57.4	118.1	167.6
Eliminations
Operating Revenues:
Transportation	(21.7)	(22.8)	(43.7)	(45.6)
Parking and lending	(0.2)	0	(0.2)	0
Storage	0	(0.1)	0	(0.1)
Other	0	0	0	0
Total operating revenues	(21.9)	(22.9)	(43.9)	(45.7)
Operating Costs and Expenses:
Fuel and transportation	(21.9)	(22.9)	(43.9)	(45.7)
Operation and maintenance	0	0	0	0
Administrative and general	0	0	0	0
Other operating costs and expenses	0	0	0	0
Total operating costs and expenses	(21.9)	(22.9)	(43.9)	(45.7)
Operating income	0	0	0	0
Other Deductions (Income):
Interest expense	0	0	0	0
Interest expense - affiliates	0	0	0	0
Interest income	0	0	0	0
Equity in earnings of subsidiaries	103.4	128.5	278.8	362.2
Equity losses in unconsolidated affiliates		0		0
Miscellaneous other income, net	0		0	0
Total other deductions	103.4	128.5	278.8	362.2
Income (loss) before income taxes	(103.4)	(128.5)	(278.8)	(362.2)
Income taxes	0	0	0	0
Net income (loss)	(103.4)	(128.5)	(278.8)	(362.2)
Net loss attributable to noncontrolling interests		0		0
Net income (loss) attributable to controlling interests	(103.4)	(128.5)	(278.8)	(362.2)
Parent Guarantor \| Reportable Legal Entities [Member]
Operating Revenues:
Transportation	0	0	0	0
Parking and lending	0	0	0	0
Storage	0	0	0	0
Other	0	0	0	0
Total operating revenues	0	0	0	0
Operating Costs and Expenses:
Fuel and transportation	0	0	0	0
Operation and maintenance	0	0	0	0
Administrative and general	(0.2)	0	(0.2)	(0.1)
Other operating costs and expenses	0.2	0	0.2	0.1
Total operating costs and expenses	0	0	0	0
Operating income	0	0	0	0
Other Deductions (Income):
Interest expense	0	0	0	0
Interest income - affiliates	(7.2)	(7.6)	(13.9)	(15.4)
Interest income	0	0	0	0
Equity in earnings of subsidiaries	(33.2)	(49.8)	(104.2)	(152.2)
Equity losses in unconsolidated affiliates		0		0
Miscellaneous other income, net	0		0	0
Total other deductions	(40.4)	(57.4)	(118.1)	(167.6)
Income (loss) before income taxes	40.4	57.4	118.1	167.6
Income taxes	0	0	0	0
Net income (loss)	40.4	57.4	118.1	167.6
Net loss attributable to noncontrolling interests		0		0
Net income (loss) attributable to controlling interests	40.4	57.4	118.1	167.6
Subsidiary Issuer \| Reportable Legal Entities [Member]
Operating Revenues:
Transportation	0	0	0	0
Parking and lending	0	0	0	0
Storage	0	0	0	0
Other	0	0	0	0
Total operating revenues	0	0	0	0
Operating Costs and Expenses:
Fuel and transportation	0	0	0	0
Operation and maintenance	0	0	0	0
Administrative and general	0	0	0	0
Other operating costs and expenses	0	0	0	0
Total operating costs and expenses	0	0	0	0
Operating income	0	0	0	0
Other Deductions (Income):
Interest expense	27.9	18.7	51.8	37.4
Interest expense - affiliates	9.1	10.2	18.6	20.4
Interest income	0	0	0	0
Equity in earnings of subsidiaries	(70.2)	(78.7)	(174.6)	(210)
Equity losses in unconsolidated affiliates		0		0
Miscellaneous other income, net	0		0	0
Total other deductions	(33.2)	(49.8)	(104.2)	(152.2)
Income (loss) before income taxes	33.2	49.8	104.2	152.2
Income taxes	0	0	0	0
Net income (loss)	33.2	49.8	104.2	152.2
Net loss attributable to noncontrolling interests		0		0
Net income (loss) attributable to controlling interests	33.2	49.8	104.2	152.2
Non-Guarantor Subsidiaries \| Reportable Legal Entities [Member]
Operating Revenues:
Transportation	278.6	268.5	590.2	595.6
Parking and lending	3	9.2	5.8	18.4
Storage	20.9	22.2	40.2	51
Other	18	16.4	36	31
Total operating revenues	320.5	316.3	672.2	696
Operating Costs and Expenses:
Fuel and transportation	45.5	52.8	94.5	108.6
Operation and maintenance	54.6	43.9	97	86.6
Administrative and general	32	30.5	62.6	57.4
Other operating costs and expenses	102.5	92.6	209.4	194.3
Total operating costs and expenses	234.6	219.8	463.5	446.9
Operating income	85.9	96.5	208.7	249.1
Other Deductions (Income):
Interest expense	18	21.5	39.3	43.7
Interest income - affiliates	(1.9)	(2.6)	(4.7)	(5)
Interest income	(0.1)	(0.2)	(0.2)	(0.3)
Equity in earnings of subsidiaries	0	0	0	0
Equity losses in unconsolidated affiliates		0.5		86.6
Miscellaneous other income, net	(0.4)		(0.6)	(0.1)
Total other deductions	15.6	19.2	33.8	124.9
Income (loss) before income taxes	70.3	77.3	174.9	124.2
Income taxes	0.1	0.1	0.3	0.3
Net income (loss)	70.2	77.2	174.6	123.9
Net loss attributable to noncontrolling interests		(1.5)		(86.1)
Net income (loss) attributable to controlling interests	$ 70.2	$ 78.7	$ 174.6	$ 210

Guarantee of Securities of Su49

Guarantee of Securities of Subsidiaries Guarantee of Securities of Subsidiaries Statements of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ 40.4	$ 55.9	$ 118.1	$ 81.5
Other comprehensive income (loss):
(Loss) gain on cash flow hedges	0	0	0	(0.9)
Reclassification adjustment transferred to Net Income from cash flow hedges	0.6	0.7	1.2	1.6
Pension and other postretirement benefit costs	(2.2)	(2)	(4.3)	(3.9)
Total Comprehensive Income (Loss)	38.8	54.6	115	78.3
Comprehensive loss attributable to noncontrolling interests	0	(1.5)	0	(86.1)
Comprehensive income (loss) attributable to controlling interests	38.8	56.1	115	164.4
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(103.4)	(128.5)	(278.8)	(362.2)
Other comprehensive income (loss):
(Loss) gain on cash flow hedges				1.8
Reclassification adjustment transferred to Net Income from cash flow hedges	(0.8)	(1)	(1.6)	(2.4)
Pension and other postretirement benefit costs	4.4	4	8.6	7.8
Total Comprehensive Income (Loss)		(125.5)		(355)
Comprehensive loss attributable to noncontrolling interests		0		0
Comprehensive income (loss) attributable to controlling interests	(99.8)	(125.5)	(271.8)	(355)
Parent Guarantor \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	40.4	57.4	118.1	167.6
Other comprehensive income (loss):
(Loss) gain on cash flow hedges				(0.9)
Reclassification adjustment transferred to Net Income from cash flow hedges	0.6	0.7	1.2	1.6
Pension and other postretirement benefit costs	(2.2)	(2)	(4.3)	(3.9)
Total Comprehensive Income (Loss)		56.1		164.4
Comprehensive loss attributable to noncontrolling interests		0		0
Comprehensive income (loss) attributable to controlling interests	38.8	56.1	115	164.4
Subsidiary Issuer \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	33.2	49.8	104.2	152.2
Other comprehensive income (loss):
(Loss) gain on cash flow hedges				(0.9)
Reclassification adjustment transferred to Net Income from cash flow hedges	0.6	0.7	1.2	1.6
Pension and other postretirement benefit costs	(2.2)	(2)	(4.3)	(3.9)
Total Comprehensive Income (Loss)		48.5		149
Comprehensive loss attributable to noncontrolling interests		0		0
Comprehensive income (loss) attributable to controlling interests	31.6	48.5	101.1	149
Non-Guarantor Subsidiaries \| Reportable Legal Entities [Member]
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	70.2	77.2	174.6	123.9
Other comprehensive income (loss):
(Loss) gain on cash flow hedges				(0.9)
Reclassification adjustment transferred to Net Income from cash flow hedges	0.2	0.3	0.4	0.8
Pension and other postretirement benefit costs	(2.2)	(2)	(4.3)	(3.9)
Total Comprehensive Income (Loss)		75.5		119.9
Comprehensive loss attributable to noncontrolling interests		(1.5)		(86.1)
Comprehensive income (loss) attributable to controlling interests	$ 68.2	$ 77	$ 170.7	$ 206

Guarantee of Securities of Su50

Guarantee of Securities of Subsidiaries Guarantee of Securities of Subsidiaries Statements of Cash Flows (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Statement of Cash Flows
Net cash provided by (used in) operating activities	$ 285.5	$ 308.1
Investing Activities:
Capital expenditures	(136.3)	(162.7)
Proceeds from sale of operating assets	0.1	2.9
Advances to affiliates, net	0	0.1
Investment in unconsolidated affiliates	0	(20.3)
Distributions from unconsolidated affiliates	0	10.7
Net cash (used in) provided by investing activities	(136.2)	(169.3)
Financing Activities:
Proceeds from long-term debt	247.1	0
Repayment of borrowings from long-term debt and term loan	(725)	0
Proceeds from borrowings on revolving credit agreement	835	220
Repayment of borrowings on revolving credit agreement, including financing fees	(558.6)	(295)
Principal payment of capital lease obligation	(0.2)	(0.2)
Advances from affiliates, net	0.1	0.1
Distributions paid	(50.4)	(49.6)
Proceeds from sale of common units	113.1	0
Capital contributions from general partner	2.3	0
Capital contributions from noncontrolling interests	0	7.8
Distributions paid to noncontrolling interests	0	(7.1)
Net cash provided by (used in) financing activities	(136.6)	(124)
Increase (decrease) in cash and cash equivalents	12.7	14.8
Cash and cash equivalents at beginning of period	6.6	28.5
Cash and cash equivalents at end of period	19.3	43.3
Eliminations
Statement of Cash Flows
Net cash provided by (used in) operating activities	0	0
Investing Activities:
Capital expenditures	0	0
Proceeds from sale of operating assets	0	0
Advances to affiliates, net	433.4	81.7
Investment in unconsolidated affiliates		0
Distributions from unconsolidated affiliates		0
Net cash (used in) provided by investing activities	433.4	81.7
Financing Activities:
Proceeds from long-term debt	0
Repayment of borrowings from long-term debt and term loan	0
Proceeds from borrowings on revolving credit agreement	0	0
Repayment of borrowings on revolving credit agreement, including financing fees	0	0
Principal payment of capital lease obligation	0	0
Advances from affiliates, net	(433.4)	(81.7)
Distributions paid	0	0
Proceeds from sale of common units	0
Capital contributions from general partner	0
Capital contributions from noncontrolling interests		0
Distributions paid to noncontrolling interests		0
Net cash provided by (used in) financing activities	(433.4)	(81.7)
Increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Parent Guarantor \| Reportable Legal Entities [Member]
Statement of Cash Flows
Net cash provided by (used in) operating activities	12.6	15.5
Investing Activities:
Capital expenditures	0	0
Proceeds from sale of operating assets	0	0
Advances to affiliates, net	(77.7)	33.8
Investment in unconsolidated affiliates		0
Distributions from unconsolidated affiliates		0
Net cash (used in) provided by investing activities	(77.7)	33.8
Financing Activities:
Proceeds from long-term debt	0
Repayment of borrowings from long-term debt and term loan	0
Proceeds from borrowings on revolving credit agreement	0	0
Repayment of borrowings on revolving credit agreement, including financing fees	0	0
Principal payment of capital lease obligation	0	0
Advances from affiliates, net	0.1	0.1
Distributions paid	(50.4)	(49.6)
Proceeds from sale of common units	113.1
Capital contributions from general partner	2.3
Capital contributions from noncontrolling interests		0
Distributions paid to noncontrolling interests		0
Net cash provided by (used in) financing activities	65.1	(49.5)
Increase (decrease) in cash and cash equivalents	0	(0.2)
Cash and cash equivalents at beginning of period	0.5	0.2
Cash and cash equivalents at end of period	0.5	0
Subsidiary Issuer \| Reportable Legal Entities [Member]
Statement of Cash Flows
Net cash provided by (used in) operating activities	(67.1)	(55.8)
Investing Activities:
Capital expenditures	0	0
Proceeds from sale of operating assets	0	0
Advances to affiliates, net	(304.4)	(16.6)
Investment in unconsolidated affiliates		0
Distributions from unconsolidated affiliates		0
Net cash (used in) provided by investing activities	(304.4)	(16.6)
Financing Activities:
Proceeds from long-term debt	247.1
Repayment of borrowings from long-term debt and term loan	0
Proceeds from borrowings on revolving credit agreement	0	0
Repayment of borrowings on revolving credit agreement, including financing fees	(3.6)	0
Principal payment of capital lease obligation	0	0
Advances from affiliates, net	129	65.1
Distributions paid	0	0
Proceeds from sale of common units	0
Capital contributions from general partner	0
Capital contributions from noncontrolling interests		0
Distributions paid to noncontrolling interests		0
Net cash provided by (used in) financing activities	372.5	65.1
Increase (decrease) in cash and cash equivalents	1	(7.3)
Cash and cash equivalents at beginning of period	1.8	9.2
Cash and cash equivalents at end of period	2.8	1.9
Non-Guarantor Subsidiaries \| Reportable Legal Entities [Member]
Statement of Cash Flows
Net cash provided by (used in) operating activities	340	348.4
Investing Activities:
Capital expenditures	(136.3)	(162.7)
Proceeds from sale of operating assets	0.1	2.9
Advances to affiliates, net	(51.3)	(98.8)
Investment in unconsolidated affiliates		(20.3)
Distributions from unconsolidated affiliates		10.7
Net cash (used in) provided by investing activities	(187.5)	(268.2)
Financing Activities:
Proceeds from long-term debt	0
Repayment of borrowings from long-term debt and term loan	(725)
Proceeds from borrowings on revolving credit agreement	835	220
Repayment of borrowings on revolving credit agreement, including financing fees	(555)	(295)
Principal payment of capital lease obligation	(0.2)	(0.2)
Advances from affiliates, net	304.4	16.6
Distributions paid	0	0
Proceeds from sale of common units	0
Capital contributions from general partner	0
Capital contributions from noncontrolling interests		7.8
Distributions paid to noncontrolling interests		(7.1)
Net cash provided by (used in) financing activities	(140.8)	(57.9)
Increase (decrease) in cash and cash equivalents	11.7	22.3
Cash and cash equivalents at beginning of period	4.3	19.1
Cash and cash equivalents at end of period	$ 16	$ 41.4