Columbia Pipeline (CPGX) 10-Q 3 Aug 15 2015 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 27, 2015
Document 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
Entity Registrant Name	COLUMBIA PIPELINE GROUP, INC./DE
Entity Central Index Key	1,629,995
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Units Outstanding		317,615,439

Statements of Consolidated Bala

Statements of Consolidated Balance Sheets - USD ($) $ in Millions		Jun. 30, 2015	Dec. 31, 2014
Current Assets
Cash and cash equivalents		$ 136.8	$ 0.5
Accounts receivable (less reserve of $0.6 and $0.6, respectively)		123.6	149.4
Accounts receivable-affiliated		678.8	180
Materials and supplies, at average cost		28.2	24.9
Exchange gas receivable		24.8	34.8
Regulatory assets		5.3	6.1
Deferred property taxes		32.3	48.9
Deferred income taxes		91.8	60
Prepayments and other		20.3	14.7
Total Current Assets		1,141.9	519.3
Investments
Unconsolidated affiliates		444.6	444.3
Other investments		12.1	2.7
Total Investments		456.7	447
Property, Plant and Equipment
Property, plant and equipment		8,476.6	7,935.4
Accumulated depreciation and amortization		(2,993)	(2,976.8)
Net Property, Plant and Equipment		5,483.6	4,958.6
Other Noncurrent Assets
Regulatory assets		149	151.9
Goodwill		1,975.5	1,975.5
Postretirement and postemployment benefits assets		110.8	90
Deferred charges and other		39.4	15.2
Total Other Noncurrent Assets		2,274.7	2,232.6
Total Assets		9,356.9	8,157.5
Current Liabilities
Current portion of long-term debt		0	115.9
Short-term borrowings		20	0
Short-term borrowings-affiliated		718.9	252.5
Accounts payable		67.6	56
Accounts payable-affiliated		29.6	53.6
Customer deposits		41.8	13.4
Taxes accrued		96.9	103.2
Exchange gas payable		24.9	34.7
Deferred revenue		13.7	22.5
Regulatory liabilities		9	1.3
Legal and environmental		2.1	2
Accrued capital expenditures		146.3	61.1
Other accruals		92.7	68
Total Current Liabilities		1,263.5	784.2
Noncurrent Liabilities
Long-term debt		2,745.9	0
Long-term debt-affiliated		0	1,472.8
Deferred income taxes		1,326.2	1,255.7
Accrued liability for postretirement and postemployment benefits		46.7	53
Regulatory liabilities		304.1	295.7
Asset retirement obligations		24.2	23.2
Other noncurrent liabilities		85.5	96.6
Total Noncurrent Liabilities		4,532.6	3,197
Total Liabilities		5,796.1	3,981.2
Equity
Net parent investment		2,635	4,210.8
Accumulated other comprehensive loss	[1]	(24.5)	(34.5)
Total CPG Equity		2,610.5	4,176.3
Noncontrolling Interest		950.3	0
Total Equity		3,560.8	4,176.3
Total Liabilities and Equity		$ 9,356.9	$ 8,157.5
[1]	All amounts are net of tax. Amounts in parentheses indicate debits.

Statements of Consolidated Bal3

Statements of Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Accounts receivable less reserve	$ 0.6	$ 0.1

Statements of Consolidated and

Statements of Consolidated and Combined Operations - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating Revenues
Transportation revenues	$ 237.8		$ 486.2
Transportation revenues-affiliated	18.5		47.5
Storage revenues	36.2		72.8
Storage revenues-affiliated	12.9		26.2
Other revenues	10.7		23.4
Total Operating Revenues	316.1		656.1
Operating Expenses
Operation and maintenance	151.1		269.5
Operation and maintenance-affiliated	24.9		52.9
Depreciation and amortization	33.9		66.4
Gain on sale of assets	(6.5)		(11.8)
Property and other taxes	19.1		38.2
Total Operating Expenses	222.5		415.2
Equity Earnings in Unconsolidated Affiliates	13.7		29.1
Operating Income	107.3		270
Other Income (Deductions)
Interest expense	(12.9)		(12.9)
Interest expense-affiliated	(11)		(29.3)
Other, net	5.3		9.9
Total Other Deductions, net	(18.6)		(32.3)
Income from Continuing Operations before Income Taxes	88.7		237.7
Income Taxes	28.6		80.5
Income from Continuing Operations	60.1		157.2
Loss from Discontinued Operations-net of taxes	(0.3)		(0.3)
Income from Continuing Operations	59.8		156.9
Less: Net income attributable to noncontrolling interest	9		16.1
Net income attributable to CPG	50.8		140.8
Income from continuing operations	$ 51.1		$ 141.1
Predecessor [Member]
Operating Revenues
Transportation revenues		$ 260.5		$ 507.4
Transportation revenues-affiliated		18.8		47.4
Storage revenues		36		72.3
Storage revenues-affiliated		13.2		26.9
Other revenues		15		35.3
Total Operating Revenues		343.5		689.3
Operating Expenses
Operation and maintenance		175.6		312.8
Operation and maintenance-affiliated		29.3		57.8
Depreciation and amortization		28.8		58.6
Gain on sale of assets		(0.3)		(17.8)
Property and other taxes		17.3		35.8
Total Operating Expenses		250.7		447.2
Equity Earnings in Unconsolidated Affiliates		11.1		20.9
Operating Income		103.9		263
Other Income (Deductions)
Interest expense		0		0
Interest expense-affiliated		(12.6)		(24.7)
Other, net		2.7		4.6
Total Other Deductions, net		(9.9)		(20.1)
Income from Continuing Operations before Income Taxes		94		242.9
Income Taxes		34.6		90.5
Income from Continuing Operations		59.4		152.4
Loss from Discontinued Operations-net of taxes		(0.3)		(0.5)
Income from Continuing Operations		59.1		151.9
Net income attributable to CPG		59.1		151.9
Income from continuing operations		$ 59.4		$ 152.4

Statements of Consolidated and5

Statements of Consolidated and Combined Comprehensive Income - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net Income		$ 59.8		$ 156.9
Net unrealized gain on cash flow hedges	[1]	0.3		0.5
Unrecognized pension and OPEB benefit (costs)	[2],[3]	0.3		7.3
Total other comprehensive income	[4]	0.6	$ 0.1	7.8	$ 0.3
Total comprehensive income		60.4		164.7
Less: Comprehensive Income-noncontrolling interest		9		16.1
Comprehensive Income-controlling interests		$ 51.4		$ 148.6
Predecessor [Member]
Net Income			59.1		151.9
Net unrealized gain on cash flow hedges	[1]		0.3		0.5
Unrecognized pension and OPEB benefit (costs)	[3]		(0.2)		(0.2)
Total other comprehensive income			0.1		0.3
Total comprehensive income			59.2		152.2
Less: Comprehensive Income-noncontrolling interest			0		0
Comprehensive Income-controlling interests			$ 59.2		$ 152.2
[1]	Net unrealized gains on derivatives qualifying as cash flow hedges, net of $0.2 million and $0.1 million tax expense for the three months ended June 30, 2015 and 2014, respectively, and $0.3 million and $0.3 million tax expense for the six months ended June 30, 2015 and 2014, respectively.
[2]	Unrecognized pension and OPEB costs are primarily related to prior period pension and OPEB remeasurement recorded during the first quarter 2015.
[3]	Unrecognized pension and other postretirement benefit (“OPEB”) costs, net of zero and $0.2 million tax benefit for the three months ended June 30, 2015 and 2014, respectively, and zero and $0.2 million tax benefit for the six months ended June 30, 2015 and 2014, respectively.
[4]	All amounts are net of tax. Amounts in parentheses indicate debits.

Statements of Consolidated and6

Statements of Consolidated and Combined Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	$ 0.2		$ (0.3)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax	$ 0		$ 0
Predecessor [Member]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax		$ 0.1		$ (0.3)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax		$ (0.2)		$ (0.2)

Statements of Consolidated and7

Statements of Consolidated and Combined Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating Activities
Net Income	$ 156.9
Adjustments to Reconcile Net Income to Net Cash from Continuing Operations:
Depreciation and amortization	66.4
Deferred income taxes and investment tax credits	31.9
Deferred revenue	(0.1)
Equity-based compensation expense and 401(k) profit sharing contribution	3.9
Gain on sale of assets	(11.8)
Income from unconsolidated affiliates	(29.1)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0.3
Amortization of Financing Costs	0.6
AFUDC equity	(8.5)
Distributions of earnings received from equity investees	27.9
Changes in Assets and Liabilities:
Accounts receivable	13.9
Accounts receivable-affiliated	1.7
Accounts payable	2.3
Accounts payable-affiliated	(26.9)
Customer deposits	1
Taxes accrued	(0.4)
Exchange gas receivable/payable	0.2
Other accruals	13.5
Prepayments and other current assets	7.8
Regulatory assets/liabilities	25.5
Postretirement and postemployment benefits	(15.5)
Deferred charges and other noncurrent assets	(2.2)
Other noncurrent liabilities	7.6
Net Cash Provided by (Used in) Operating Activities, Continuing Operations	266.9
Cash Provided by (Used in) Operating Activities, Discontinued Operations	(0.1)
Net Cash Flows from Operating Activities	266.8
Investing Activities
Capital expenditures	(470.2)
Proceeds from Insurance Settlement, Investing Activities	2.1
Change in short-term lendings-affiliated	(500.2)
Proceeds from disposition of assets	17.3
Distributions from (contributions to) equity investees	2.2
Other investing activities	(17)
Net Cash Flows used for Investing Activities	(965.8)
Financing Activities
Change in short-term borrowings-affiliated	20
Proceeds from (Repayments of) Short-term Debt to Related Parties	466.3
Issuance of long-term debt	2,745.9
Debt related costs	(22.5)
Issuance of long-term debt-affiliated	1,217.3
Payments of long-term debt-affiliated, including current portion	(2,806)
Proceeds from the issuance of common units, net of offering costs	1,168.4
Distribution of IPO proceeds to parent	(500)
Distribution to parent	(1,450)
Payments to Noncontrolling Interests	(4.9)
Transfer from parent	0.8
Net Cash Flows from (used for) Financing Activities	835.3
Change in cash and cash equivalents	136.3
Cash and cash equivalents at beginning of period	0.5
Cash and Cash Equivalents at End of Period	$ 136.8
Predecessor [Member]
Operating Activities
Net Income		$ 151.9
Adjustments to Reconcile Net Income to Net Cash from Continuing Operations:
Depreciation and amortization		58.6
Deferred income taxes and investment tax credits		47.6
Deferred revenue		2
Equity-based compensation expense and 401(k) profit sharing contribution		1.7
Gain on sale of assets		(17.8)
Income from unconsolidated affiliates		(20.9)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent		0.5
Amortization of Financing Costs		0
AFUDC equity		(4.3)
Distributions of earnings received from equity investees		12.9
Changes in Assets and Liabilities:
Accounts receivable		(25.2)
Accounts receivable-affiliated		19.1
Accounts payable		24.3
Accounts payable-affiliated		(17.7)
Customer deposits		75.2
Taxes accrued		(9.4)
Exchange gas receivable/payable		4.7
Other accruals		4.3
Prepayments and other current assets		20.5
Regulatory assets/liabilities		25.6
Postretirement and postemployment benefits		(11.1)
Deferred charges and other noncurrent assets		(3.3)
Other noncurrent liabilities		(0.8)
Net Cash Provided by (Used in) Operating Activities, Continuing Operations		338.4
Cash Provided by (Used in) Operating Activities, Discontinued Operations		(1)
Net Cash Flows from Operating Activities		337.4
Investing Activities
Capital expenditures		(296.6)
Proceeds from Insurance Settlement, Investing Activities		6.8
Change in short-term lendings-affiliated		(10.4)
Proceeds from disposition of assets		4.9
Distributions from (contributions to) equity investees		(54.8)
Other investing activities		(3.4)
Net Cash Flows used for Investing Activities		(353.5)
Financing Activities
Change in short-term borrowings-affiliated		0
Proceeds from (Repayments of) Short-term Debt to Related Parties		(312.6)
Issuance of long-term debt		0
Debt related costs		0
Issuance of long-term debt-affiliated		328.4
Payments of long-term debt-affiliated, including current portion		0
Proceeds from the issuance of common units, net of offering costs		0
Distribution of IPO proceeds to parent		0
Distribution to parent		0
Payments to Noncontrolling Interests		0
Transfer from parent		0
Net Cash Flows from (used for) Financing Activities		15.8
Change in cash and cash equivalents		(0.3)
Cash and cash equivalents at beginning of period		0.4
Cash and Cash Equivalents at End of Period		$ 0.1

Statements of Consolidated Equi

Statements of Consolidated Equity - 6 months ended Jun. 30, 2015 - Scenario, Unspecified [Domain] - USD ($) $ in Millions		Total		Noncontrolling Interest [Member]	Accumulated Other Comprehensive Income (Loss)	Parent [Member]
Net Income (Loss) Attributable to Parent		$ 140.8
Beginning Balance at Dec. 31, 2014		4,176.3		$ 0	$ (34.5)	$ 4,210.8
Net Income		156.9			0
Income (Loss) Attributable to Noncontrolling Interest		16.1
Other Comprehensive Income (Loss), Net of Tax		7.8	[1]	0	7.8	0
Allocation of Accumulated Other Comprehensive Loss To Noncontrolling Interest		0		(2.2)	2.2	0
Issuance of common units of CPPL		1,168.4		1,168.4	0	0
Payments of Capital Distribution		(500)		0	0	(500)
Distribution to Parent		(1,450)		0	0	(1,450)
Purchase of additional interest in Columbia OpCo	[2]	0		(227.1)	0	227.1
Distribution of IPO proceeds to NiSource		(4.9)		(4.9)	0	0
Net Transfers (To) From Parent		6.3		0	0	6.3
Ending Balance at Jun. 30, 2015		$ 3,560.8		$ 950.3	$ (24.5)	$ 2,635
[1]	All amounts are net of tax. Amounts in parentheses indicate debits.
[2]	Represents the sale of an additional 8.4% limited partner interest in Columbia OpCo, recorded at the historical carrying value of Columbia OpCo’s net assets after giving effect to the $1,168.4 million equity contribution. This decreases the noncontrolling interest by the same amount it increases the net parent investment because the CPPL’s purchase price for its additional 8.4% interest in Columbia OpCo exceeded book value.

Statements of Consolidated Equ9

Statements of Consolidated Equity (Parenthetical) - Jun. 30, 2015 - USD ($) $ in Millions	Total	Total
Issuance of common units of CPPL	$ 1,168.4	$ 1,168.4
Columbia OpCo
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Additional Ownership Interest	8.40%

Basis of Accounting Presentatio

Basis of Accounting Presentation	6 Months Ended
	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting Presentation	Basis of Accounting Presentation Columbia Pipeline Group, Inc. ("CPG") is a growth-oriented Delaware corporation formed by NiSource on September 26, 2014 to own, operate and develop a portfolio of pipelines, storage and related midstream assets. Together with the closing of CPPL's IPO, NiSource contributed its subsidiary CEG to CPG. CPG owns and operates, through its subsidiaries, approximately 15,000 miles of strategically located interstate gas pipelines extending from New York to the Gulf of Mexico and one of the nation’s largest underground natural gas storage systems, with approximately 300 MMDth of working gas capacity, as well as related gathering and processing assets. CPG indirectly owns the general partner of CPPL and all of CPPL’s incentive distribution rights. CPG did not have any material assets or liabilities as a separate corporate entity until the contribution from NiSource on February 11, 2015. As a result of this contribution, the financial statements for periods as of and subsequent to September 26, 2014 reflect the consolidated financial position, results of operations and cash flows for CPG. All periods prior to September 26, 2014 reflect the combined financial position, results of operations and cash flows for CPG's predecessor (the "Predecessor"). On June 2, 2015, NiSource announced that its board of directors had approved the separation of CPG from NiSource (the "Separation") through the distribution of CPG common stock to holders of NiSource common stock as of June 19, 2015 (the "Record Date"). On July 1, 2015, holders of NiSource common stock received one share of CPG common stock for each share of NiSource common stock held at 5:00 pm, Central Time, on the Record Date. Stockholders who were entitled to receive shares of CPG common stock in this distribution were not required to pay any cash or deliver any other consideration, including any shares of NiSource common stock, to receive shares of CPG common stock. As of July 1, 2015, CPG is an independent, publicly traded company, and NiSource does not retain any ownership interest in CPG. CPG began trading on the New York Stock Exchange on July 2, 2015. CPG is engaged in regulated gas transportation and storage services for local distribution companies, marketers, producers and industrial and commercial customers located in northeastern, mid-Atlantic, Midwestern and southern states and the District of Columbia along with unregulated businesses that include midstream services, including gathering, treating, conditioning, processing, compression and liquids handling, and development of mineral rights positions. The regulated services are performed under a tariff at rates subject to FERC approval. The Condensed Consolidated and Combined Financial Statements (unaudited) have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations, although CPG believes that the disclosures made are adequate to make the information not misleading. These financial statements should be read in conjunction with the Company’s audited consolidated and combined financial statements for the year ended December 31, 2014. These financial statements reflect all normal recurring adjustments that are, in the opinion of management, necessary to fairly present CPG’s results of operations and financial position. Amounts reported in the Condensed Statements of Consolidated and Combined Operations (unaudited) are not necessarily indicative of amounts expected for the respective annual periods. CPG’s accompanying Condensed Consolidated and Combined Financial Statements (unaudited) have been prepared in accordance with GAAP on the basis of NiSource’s historical ownership of CPG’s assets and its operations. These financial statements include the accounts of the following subsidiaries: Columbia Gas Transmission, Columbia Gulf, Columbia Midstream, CEVCO, CNS Microwave, Crossroads, CPGSC, CEG, Columbia Remainder Corporation, CPP GP LLC, CPPL, OpCo GP, Columbia OpCo and CPG. Also included in the Condensed Consolidated and Combined Financial Statements (unaudited) are equity method investments Hardy Storage, Millennium Pipeline, and Pennant. All intercompany transactions and balances have been eliminated.

CPPL Initial Public Offering

CPPL Initial Public Offering	6 Months Ended
	Jun. 30, 2015
Equity [Abstract]
CPPL Initial Public Offering	CPPL Initial Public Offering On December 5, 2007, NiSource formed CPPL (NYSE: CPPL) to own, operate and develop a portfolio of pipelines, storage and related assets. On February 11, 2015 , CPPL completed its offering of 53.8 million common units representing limited partner interests, constituting 53.5% of CPPL's outstanding limited partner interests. CPPL received $1,168.4 million of net proceeds from IPO. CPG owns the general partner of CPPL, all of CPPL's subordinated units and the incentive distribution rights. The assets of CPPL consist of a 15.7% limited partner interest in Columbia OpCo, which prior to the Separation, consisted of substantially all of NiSource's Columbia Pipeline Group Operations segment. The operations of CPPL will be consolidated in CPG’s results. As of June 30, 2015 , the portion of CPPL owned by the public is reflected as a noncontrolling interest in the Condensed Consolidated and Combined Financial Statements (unaudited). The table below summarizes the effects of changes in CPG’s ownership interest in Columbia OpCo on equity: Three Months Ended Six Months Ended (in millions) 2015 2015 Net income attributable to CPG $ 50.8 $ 140.8 Increase in CPG’s net parent investment for the sale of 8.4% of Columbia OpCo — 227.1 Change from net income attributable to CPG and transfers to noncontrolling interest $ 50.8 $ 367.9

Recent Accounting Pronouncement

Recent Accounting Pronouncements	6 Months Ended
	Jun. 30, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). ASU 2014-09 outlines a single, comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. The core principle of the new standard is that an entity should recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In July 2015, the FASB extended the adoption date for ASU 2014-09 to periods beginning after December 15, 2017, including interim periods, and the new standard is to be applied retrospectively with early adoption not permitted. CPG is currently evaluating the impact the adoption of ASU 2014-09 will have on the Condensed Consolidated and Combined Financial Statements (unaudited) or Notes to Condensed Consolidated and Combined Financial Statements (unaudited). In April 2015, the FASB issued ASU 2015-05, Intangibles - Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. ASU 2015-05 clarifies guidance on determining whether a cloud computing arrangement contains a software license that should be accounted for as internal-use software. CPG is required to adopt ASU 2015-05 for periods beginning after December 15, 2015, including interim periods, and the guidance is permitted to be applied either (1) prospectively to all agreements entered into or materially modified after the effective date or (2) retrospectively, with early adoption permitted. CPG is currently evaluating the impact the adoption of ASU 2015-05 will have on the Condensed Consolidated and Combined Financial Statements (unaudited) or Notes to Condensed Consolidated and Combined Financial Statements (unaudited). In April 2015, the FASB issued ASU 2015-03, Interest - Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs. ASU 2015-03 changes the way entities present debt issuance costs in financial statements by presenting issuance costs on the balance sheet as a direct deduction from the related liability rather than as a deferred charge. Amortization of these costs will continue to be reported as interest expense. CPG is required to adopt ASU 2015-03 for periods beginning after December 15, 2015, including interim periods, and the guidance is to be applied retrospectively with early adoption permitted. CPG is currently evaluating the impact the adoption of ASU 2015-03 will have on the Condensed Consolidated and Combined Financial Statements (unaudited) or Notes to Condensed Consolidated and Combined Financial Statements (unaudited). In February 2015, the FASB issued ASU 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis . ASU 2015-02 amends consolidation guidance by including changes to the variable and voting interest models used by entities to evaluate whether an entity should be consolidated. CPG is required to adopt ASU 2015-02 for periods beginning after December 15, 2015, including interim periods, and the guidance is to be applied retrospectively or using a modified retrospective approach, with early adoption permitted. CPG is currently evaluating the impact the adoption of ASU 2015-02 will have on the Condensed Consolidated and Combined Financial Statements (unaudited) or Notes to Condensed Consolidated and Combined Financial Statements (unaudited).

Transactions with Affiliates

Transactions with Affiliates	6 Months Ended
	Jun. 30, 2015
Related Party Transactions [Abstract]
Transactions with Affiliates	Transactions with Affiliates In the normal course of business, CPG engages in transactions with subsidiaries of NiSource, which prior to the Separation were deemed to be affiliates of CPG. These affiliate transactions are summarized in the tables below: Statement of Operations. Three Months Ended Six Months Ended (in millions) 2015 2014 2015 2014 Predecessor Predecessor Transportation revenues $ 18.5 $ 18.8 $ 47.5 $ 47.4 Storage revenues 12.9 13.2 26.2 26.9 Other revenues 0.1 0.1 0.2 0.2 Operation and maintenance expense 24.9 29.3 52.9 57.8 Interest expense 11.0 12.6 29.3 24.7 Interest income 3.4 0.2 4.4 0.3 Balance Sheet. (in millions) June 30, 2015 December 31, 2014 Accounts receivable $ 678.8 $ 180.0 Current portion of long-term debt — 115.9 Short-term borrowings 718.9 252.5 Accounts payable 29.6 53.6 Long-term debt — 1,472.8 Transportation, Storage and Other Revenues . CPG provides natural gas transportation, storage and other services to subsidiaries of NiSource. Operation and Maintenance Expense . CPG receives executive, financial, legal, information technology and other administrative and general services from an affiliate, NiSource Corporate Services. Expenses incurred as a result of these services consist of employee compensation and benefits, outside services and other expenses. CPG is charged directly or allocated using various allocation methodologies based on a combination of gross fixed assets, total operating expense, number of employees and other measures. Management believes the allocation methodologies are reasonable. However, these allocations and estimates may not represent the amounts that would have been incurred had the services been provided by an outside entity. Interest Expense and Income . For the three months ended June 30, 2015 and 2014 , CPG was charged interest for long-term debt of $12.0 million and $13.9 million , respectively, offset by associated AFUDC of $1.4 million and $2.0 million , respectively. For the six months ended June 30, 2015 and 2014 , CPG was charged interest for long-term debt of $31.0 million and $26.1 million , respectively, offset by associated AFUDC of $2.4 million and $3.2 million , respectively. Columbia OpCo and its subsidiaries entered into an intercompany money pool agreement with NiSource Finance, which became effective on the closing date of CPPL’s IPO. The money pool is available for Columbia OpCo and its subsidiaries’ general purposes, including capital expenditures and working capital. This intercompany money pool agreement is discussed in connection with Short-term Borrowings below. Prior to CPPL’s IPO, the subsidiaries of CPG participated in a similar money pool agreement with NiSource Finance. NiSource Corporate Services administers the money pools. The cash accounts maintained by the subsidiaries of Columbia OpCo and CPG are swept into a NiSource corporate account on a daily basis, creating an affiliated receivable or decreasing an affiliated payable, as appropriate, between NiSource and the subsidiary. The amount of interest expense and income for short-term borrowings is determined by the net position of each subsidiary in the money pool. The money pool weighted-average interest rate at June 30, 2015 and 2014 was 1.21% and 0.64% , respectively. For the three months ended June 30, 2015 and 2014 , the interest expense for short-term borrowings charged was $0.4 million and $0.7 million , respectively. For the six months ended June 30, 2015 and 2014 , the interest expense for short-term borrowings charged was $0.7 million and $1.8 million , respectively. Accounts Receivable . CPG includes in accounts receivable amounts due from the money pool discussed above of $645.9 million and $125.0 million at June 30, 2015 and December 31, 2014 , respectively, for subsidiaries in a net deposit position. Also included in the balance at June 30, 2015 and December 31, 2014 are amounts due from subsidiaries of NiSource for transportation and storage services of $32.9 million and $28.8 million , respectively. Net cash flows related to the money pool receivables are included as Investing Activities on the Condensed Statements of Consolidated and Combined Statements of Cash Flows (unaudited). All other affiliated receivables are included as Operating Activities. Short-term Borrowings . The subsidiaries of CPG entered into an intercompany money pool agreement with NiSource Finance with $750.0 million of reserved borrowing capacity. Following the Separation, the agreement is with CPG. In furtherance of the money pool agreement, CPG entered into a $1,500.0 million revolving credit agreement on December 5, 2014. The CPG revolving credit agreement became effective at the completion of the Separation. Each of CEG, OpCo GP and Columbia OpCo is a guarantor of CPG’s revolving credit facility. As guarantors and restricted subsidiaries, CEG, OpCo GP and Columbia OpCo are subject to various customary covenants and restrictive provisions which, among other things, limit CPG’s and its restricted subsidiaries’ ability to incur additional indebtedness, guarantees and/or liens, consolidate, merge or transfer all or substantially all of their assets, make certain investments or restricted payments, modify certain material agreements, engage in certain types of transactions with affiliates, dispose of assets, and prepay certain indebtedness, each of which is subject to customary and usual exceptions and baskets, including an exception to the limitation on restricted payments for distributions of available cash, as permitted by their organizational documents. The restricted payment provision does not prohibit CPG or any of its restricted subsidiaries from making distributions in accordance with their respective organizational documents unless there has been an event of default (as defined in the revolving credit agreement), and neither CPG nor any of its restricted subsidiaries has any restrictions on its ability to make distributions under its organizational documents. Under Columbia OpCo’s partnership agreement, it is required to distribute all of its available cash each quarter, less the amounts of cash reserves that OpCo GP determines are necessary or appropriate in its reasonable discretion to provide for the proper conduct of Columbia OpCo’s business. In addition, subject to Delaware law, the board of CPG may similarly determine whether to declare dividends at CPG without restriction under its revolving credit agreement. At June 30, 2015 , neither CPG nor its consolidated subsidiaries had any restricted net assets. If Columbia OpCo and the other loan parties fail to perform their obligations under these and other covenants, it could adversely affect Columbia OpCo’s ability to finance future business opportunities and make cash distributions to CPG. CPG’s revolving credit agreement also contains customary events of default, including cross default provisions that apply to any other indebtedness CPG may have with an outstanding principal amount in excess of $50.0 million . If a default occurred, the relevant lenders could elect to declare the debt, together with accrued interest and other fees, to be immediately due and payable and proceed against Columbia OpCo as a guarantor. The balance of Short-term Borrowings at June 30, 2015 and December 31, 2014 of $718.9 million and $252.5 million , respectively, includes those subsidiaries of CPG in a net borrower position of the NiSource Finance money pool discussed above. Net cash flows related to Short-term Borrowings are included as Financing Activities on the Condensed Statements of Consolidated and Combined Cash Flows (Unaudited). Accounts Payable . The affiliated accounts payable primarily includes amounts due for services received from NiSource Corporate Services and interest payable to NiSource Finance. Long-term Debt . CPG’s long-term financing requirements prior to the private placement of senior notes on May 22, 2015 were satisfied through borrowings from NiSource Finance. CPG used a portion of net proceeds from the senior notes to repay approximately $1,087.3 million of intercompany debt and short-term borrowings, net of amounts due from the money pool, between CPG and NiSource Finance. Details of the affiliated long-term debt balance are summarized in the table below: Origination Date Interest Rate Maturity Date June 30, 2015 December 31, 2014 (in millions) Predecessor November 28, 2005 (1) 5.41 % November 30, 2015 $ — $ 115.9 November 28, 2005 5.45 % November 28, 2016 — 45.3 November 28, 2005 5.92 % November 28, 2025 — 133.5 November 28, 2012 4.63 % November 28, 2032 — 45.0 November 28, 2012 4.94 % November 30, 2037 — 95.0 December 19, 2012 5.16 % December 21, 2037 — 55.0 November 28, 2012 5.26 % November 28, 2042 — 170.0 December 19, 2012 5.49 % December 18, 2042 — 95.0 December 9, 2013 (2) 4.75 % December 31, 2016 — 834.0 Total Long-term Debt $ — $ 1,588.7 (1) The debt balance for the note originating on November 28, 2005 and maturing on November 30, 2015 is included in "Current portion of long-term debt-affiliated" on the Condensed Consolidated Balance Sheets as of December 31, 2014. (2) CPG may borrow at any time from the origination date to the maturity date not to exceed $2.6 billion . The note carries a variable interest rate of prime plus 150 basis points. All funds borrowed on the note are due December 31, 2016 . Dividends . During the six months ended June 30, 2015 , CPG distributed $500.0 million of the proceeds from CPPL’s IPO to NiSource as a reimbursement of preformation capital expenditures with respect to the assets contributed to Columbia OpCo and $1,450.0 million of proceeds related to the issuance of senior notes in May 2015. CPG paid no dividends to NiSource in the six months ended June 30, 2014 . There were no restrictions on the payment by CPG of dividends to NiSource.

Short-Term Borrowings

Short-Term Borrowings	6 Months Ended
	Jun. 30, 2015
Short-term Debt [Abstract]
Short-Term Borrowings	Short-Term Borrowings CPG Revolving Credit Facility. On December 5, 2014, CPG entered into a $1,500.0 million senior revolving credit facility, of which $250.0 million in letters of credit is available. The revolving credit facility became effective as of the Separation. CPG expects that $750.0 million of this facility will be utilized as credit support for Columbia OpCo and its subsidiaries and the remaining $750.0 million of this facility will be available for CPG’s general corporate purposes, including working capital. Obligations under the CPG revolving credit facility are unsecured. Loans under the CPG revolving credit facility will bear interest at CPG’s option at either (i) the greatest of (a) the federal funds effective rate plus 0.500 percent , (b) the reference prime rate of JPMorgan Chase Bank, N.A., or (c) the Eurodollar rate which is based on the London Interbank Offered Rate (LIBOR), plus 1.000 percent , each of which is subject to a margin that varies from 0.000 percent to 0.650 percent per annum, according to the credit rating of CPG, or (ii) the Eurodollar rate plus a margin that varies from 1.000 percent to 1.650 percent per annum, according to the credit rating of CPG. CPG’s revolving credit facility is subject to a facility fee that varies from 0.125 percent to 0.350 percent per annum, according to CPG’s credit rating. Revolving indebtedness under the CPG credit facility will rank equally with all of CPG’s outstanding unsecured and unsubordinated debt. CEG, OpCo GP and Columbia OpCo have each fully guaranteed the CPG credit facility. The CPG revolving credit facility contains various customary covenants and restrictive provisions which, among other things, limit CPG’s and its restricted subsidiaries’ ability to incur additional indebtedness, guarantees and/or liens; consolidate, merge or transfer all or substantially all of their assets; make certain investments or restricted payments; modify certain material agreements; engage in certain types of transactions with affiliates; dispose of assets; and prepay certain indebtedness, each of which is subject to customary and usual exceptions and baskets, including an exception to the limitation on restricted payments for distributions of available cash, as permitted by their organizational documents. The restricted payment provision does not prohibit CPG or any of its restricted subsidiaries from making distributions in accordance with their respective organizational documents unless there has been an event of default (as defined in the revolving credit agreement), and neither CPG nor any of its restricted subsidiaries has any restrictions on its ability to make distributions under its organizational documents. Under Columbia OpCo's partnership agreement, it is required to distribute all of its available cash each quarter, less the amounts of cash reserves that OpCo GP determines are necessary or appropriate in its reasonable discretion to provide for the proper conduct of Columbia OpCo’s business. In addition, subject to Delaware law, the board of CPG may similarly determine whether to declare dividends at CPG without restriction under its revolving credit agreement. At June 30, 2015 , neither CPG nor its consolidated subsidiaries had any restricted net assets. If Columbia OpCo and the other loan parties fail to perform their obligations under these and other covenants, it could adversely affect Columbia OpCo’s ability to finance future business opportunities and make cash distributions to CPG. The CPG revolving credit facility also contains customary events of default, including cross default provisions that apply to any other indebtedness CPG may have with an outstanding principal amount in excess of $50.0 million . The CPG revolving credit facility also contains certain financial covenants that require CPG to maintain a consolidated total leverage ratio that does not exceed (i) 5.75 to 1.00 for any period of four consecutive fiscal quarters (each, a “test period”) ending December 31, 2015, (ii) 5.50 to 1.00 for any test period ending after December 31, 2015 and on or before December 31, 2017, and (iii) 5.00 to 1.00 for any test period ending after December 31, 2017, provided that after December 31, 2017, and during a Specified Acquisition Period (as defined in the CPG revolving credit facility), the leverage ratio may not exceed 5.50 to 1.00 . A breach of any of these covenants could result in a default in respect of the related debt. If a default occurred, the relevant lenders could elect to declare the debt, together with accrued interest and other fees, to be immediately due and payable and proceed against CPG or any guarantor. As of June 30, 2015 , CPG had no borrowings outstanding and issued no letters of credit under the revolving credit facility. CPPL Revolving Credit Facility. On December 5, 2014, CPPL entered into a $500.0 million senior revolving credit facility, of which $50.0 million in letters of credit is available. The revolving credit facility became effective at the closing of CPPL's IPO. The credit facility is available for general partnership purposes, including working capital and capital expenditures, including the funding of capital calls. CPPL’s obligations under the revolving credit facility are unsecured. The loans thereunder bear interest at CPPL’s option at either (i) the greatest of (a) the federal funds effective rate plus 0.500 percent , (b) the reference prime rate of Wells Fargo Bank, National Association or (c) the Eurodollar rate which is based on the London Interbank Offered Rate (“LIBOR”), plus 1.000 percent , each of which is subject to a margin that varies from 0.000 percent to 0.650 percent per annum, according to the credit rating of CPG, or (ii) the Eurodollar rate plus a margin that varies from 1.000 percent to 1.650 percent per annum, according to the credit rating of CPG. The revolving credit facility is subject to a facility fee that varies from 0.125 percent to 0.350 percent per annum, according to the credit rating of CPG. The revolving indebtedness under CPPL's credit facility ranks equally with all CPPL’s outstanding unsecured and unsubordinated debt. CPG, CEG, OpCo GP and Columbia OpCo have each fully guaranteed CPPL's credit facility. CPPL’s revolving credit facility contains various covenants and restrictive provisions which, among other things, limit CPPL’s ability and CPPL’s restricted subsidiaries’ ability to incur additional indebtedness, guarantees and/or liens; consolidate, merge or transfer all or substantially all of CPPL’s assets; make certain investments or restricted payments; modify certain material agreements; engage in certain types of transactions with affiliates; dispose of assets; and prepay certain indebtedness; each of which is subject to customary and usual exceptions and baskets, including an exception to the limitation on restricted payments for distributions of available cash, as permitted by CPPL’s organizational documents. The restricted payment provision does not prohibit CPPL or any of its restricted subsidiaries from making distributions in accordance with their respective organizational documents unless there has been an event of default (as defined in the CPPL revolving credit agreement), and neither CPPL nor any of its restricted subsidiaries has any restrictions on its ability to make distributions under its organizational documents. In particular, in accordance with CPPL's partnership agreement, the general partner has adopted a policy that CPPL will make quarterly cash distributions in amounts equal to at least the minimum quarterly distributions of $0.1675 on each common and subordinated unit. However, the determination to make any distributions of cash is subject to the discretion of the general partner. At June 30, 2015 , neither CPPL nor its consolidated subsidiaries had any restricted net assets. If CPPL fails to perform the obligations under these and other covenants, the revolving credit commitment could be terminated and any outstanding borrowings, together with accrued interest, under the revolving credit facility could be declared immediately due and payable. CPPL’s revolving credit facility also contains customary events of default, including cross default provisions that apply to any other indebtedness it may have with an outstanding principal amount in excess of $50.0 million . The revolving credit facility also contains certain financial covenants that require CPPL to maintain a consolidated total leverage ratio that does not exceed (i) 5.75 to 1.00 for the period of four consecutive fiscal quarters (“test period”) ending December 31, 2015, (ii) 5.50 to 1.00 for any test period ending after December 31, 2015 and on or before December 31, 2017, and (iii) 5.00 to 1.00 for any test period ending after December 31, 2017, provided that after December 31, 2017 and during a Specified Acquisition Period (as defined in the revolving credit facility), the leverage ratio shall not exceed 5.50 to 1.00 . As of June 30, 2015 , CPPL had $20.0 million in outstanding borrowings and issued no letters of credit under the revolving credit facility.

Long-Term Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2015
Debt Instrument [Line Items]
Long-Term Debt	Long-Term Debt Senior notes issuance. On May 22, 2015, CPG closed its private placement of $2,750.0 million in aggregated principal amount of its senior notes, comprised of $500.0 million of 2.45% senior notes due 2018 (the “2018 Notes”), $750.0 million of 3.30% senior notes due 2020 (the “2020 Notes”), $1,000.0 million of 4.50% senior notes due 2025 (the “2025 Notes”) and $500.0 million of 5.80% senior notes due 2045 (the “2045 Notes” and, together with the 2018 Notes, 2020 Notes and 2025 Notes, the “Notes”). The Notes were issued at a discount, for net proceeds of approximately $2,722.2 million after deducting the Initial Purchasers’ discount and estimated offering expenses of CPG. Indenture. The Notes are governed by an Indenture, dated as of May 22, 2015 (the “Indenture”), entered into by CPG and the certain subsidiary guarantors named therein (the "Guarantors") with U.S. Bank National Association, as trustee (the “Trustee”). The initial Guarantors are three wholly owned subsidiaries of CPG, CEG, Columbia OpCo and OpCo GP. The Notes are fully and unconditionally guaranteed, jointly and severally, on a senior unsecured basis by all of the Guarantors. Each guarantee of CPG’s obligations under the Notes is a direct, unsecured and unsubordinated obligation of the applicable Guarantor and has the same ranking with respect to indebtedness of that Guarantor as the Notes have with respect to CPG’s indebtedness. The Indenture governing the Notes contains covenants that, among other things, limit the ability of CPG and certain of its subsidiaries to incur liens, to enter into sale and lease-back transactions and to enter into mergers, consolidations or transfers of all or substantially all of their assets. The Indenture also contains customary events of default. The 2018 Notes will mature on June 1, 2018 , the 2020 Notes will mature on June 1, 2020 , the 2025 Notes will mature on June 1, 2025 and the 2045 Notes will mature on June 1, 2045 . Interest on the Notes of each series will be payable semi-annually in arrears on June 1 and December 1, commencing on December 1, 2015. Registration Rights Agreement. In connection with the private placement of the Notes, CPG and the Guarantors entered into a Registration Rights Agreement (the “Registration Rights Agreement”) with the Initial Purchasers, pursuant to which CPG and the Guarantors agreed to file, and use their reasonable best efforts to cause to become effective, an exchange offer registration statement with the SEC and to consummate an exchange offer within 360 days after the date of issuance of the Notes pursuant to which holders of each series of the Notes can exchange the Notes issued in the offering for registered notes having the same terms as the Notes. Under certain circumstances set forth in the Registration Rights Agreement, in lieu of a registered exchange offer, CPG and the Guarantors must file, and use reasonable best efforts to cause to become effective, a shelf registration statement for the resale of the Notes. If CPG fails to satisfy these obligations on a timely basis, the annual interest borne by the Notes will be increased by up to 0.50% per annum until the exchange offer is completed or the shelf registration statement is declared effective.

Gain on Sale of Assets

Gain on Sale of Assets	6 Months Ended
	Jun. 30, 2015
Gain On Sale of Assets [Abstract]
Gain on Sale of Assets	Gain on Sale of Assets CPG recognizes gains on conveyances of mineral rights positions into earnings as any obligation associated with conveyance is satisfied. For the three months ended June 30, 2015 and 2014 , gains on conveyances amounted to $8.3 million and $0.3 million , respectively, and are included in "Gain on sale of assets" on the Condensed Statements of Consolidated and Combined Operations (unaudited). For the six months ended June 30, 2015 and 2014 , gains on conveyances amounted to $13.6 million and $17.8 million , respectively, and are included in "Gain on sale of assets" on the Condensed Statements of Consolidated and Combined Operations (unaudited). As of June 30, 2015 and December 31, 2014 , deferred gains of approximately $10.9 million and $19.6 million , respectively, were deferred pending performance of future obligations and recorded within "Deferred revenue," on the Condensed Consolidated Balance Sheets (unaudited).

Goodwill

Goodwill	6 Months Ended
	Jun. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill CPG tests its goodwill for impairment annually as of May 1 unless indicators, events or circumstances would require an immediate review. Goodwill is tested for impairment using financial information at the reporting unit level, referred to as the Columbia Gas Transmission Operations reporting unit, which is consistent with the level of discrete financial information reviewed by operating segment management. The Columbia Gas Transmission Operations reporting unit includes the following entities: Columbia Gas Transmission (including its equity method investment in the Millennium Pipeline joint venture), Columbia Gulf and the equity method investment in Hardy Storage, all of which have been designated as components and aggregated based on the regulated nature of their operations and similar economic characteristics (e.g., the offering of FERC-regulated pipeline transportation and storage services to LDCs, municipal utilities, direct industrial users, electric power generators and marketers). All of the goodwill relates to NiSource’s acquisition of CEG in 2000. CPG’s goodwill assets at June 30, 2015 were $1,975.5 million . CPG completed a quantitative (“step 1”) fair value measurement of the reporting unit during the May 1, 2012 goodwill test. The test indicated that the fair value of the reporting unit substantially exceeded the carrying value, indicating that no impairment existed. GAAP allows entities testing goodwill for impairment the option of performing a qualitative (“step 0”) assessment before calculating the fair value of a reporting unit for the goodwill impairment test. If a step 0 assessment is performed, an entity is no longer required to calculate the fair value of a reporting unit unless the entity determines that, based on that assessment, it is more likely than not that its fair value is less than its carrying amount. CPG applied the qualitative step 0 analysis to its reporting unit for the annual impairment test performed as of May 1, 2015 . For the current year test, CPG assessed various assumptions, events and circumstances that would have affected the estimated fair value of the reporting unit as compared to its base line May 1, 2012 step 1 fair value measurement. The results of this assessment indicated that it is not more likely than not that its reporting unit fair value is less than the reporting unit carrying value. CPG considered whether there were any events or changes in circumstances subsequent to the annual test that would reduce the fair value of the reporting unit below its carrying amount and necessitate another goodwill impairment test. No such indicators were noted that would require a subsequent goodwill impairment test during the second quarter of 2015 .

Asset Retirement Obligations

Asset Retirement Obligations	6 Months Ended
	Jun. 30, 2015
Asset Retirement Obligation [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations Changes in CPG’s liability for asset retirement obligations for the six months ended June 30, 2015 and 2014 are presented in the table below: (in millions) 2015 2014 Predecessor Balance as of January 1, $ 23.2 $ 26.3 Accretion expense 0.6 0.8 Additions 0.4 2.0 Settlements — — Change in estimated cash flows — (0.2 ) Balance as of June 30, $ 24.2 $ 28.9 CPG's asset retirement obligations above relate to the modernization program of pipelines and transmission facilities, the retiring of offshore facilities, polychlorinated biphenyl ("PCB") remediation and asbestos removal at several compressor and measuring stations. CPG recognizes that there are obligations to incur significant costs to retire wells associated with gas storage operations; however, the lives of these wells are indeterminable until management establishes plans for closure.

Regulatory Matters

Regulatory Matters	6 Months Ended
	Jun. 30, 2015
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Matters	Regulatory Matters Columbia Gas Transmission Customer Settlement. In January 2015, Columbia Gas Transmission commenced the third year of the Columbia Gas Transmission long-term system modernization program. Columbia Gas Transmission expects to invest approximately $300 million in modernization investments during the year. Recovery of approximately $320 million of investments made in 2014 began on February 1, 2015. Cost Recovery Trackers and other similar mechanisms. A significant portion of the transmission and storage regulated companies' revenue is related to the recovery of their operating costs, the review and recovery of which occurs via standard regulatory proceedings with the FERC under section 4 of the Natural Gas Act. However, certain operating costs of the Columbia OpCo regulated transmission and storage companies are significant and recurring in nature, such as fuel for compression and lost and unaccounted for gas. The FERC allows for the recovery of such costs via cost tracking mechanisms. These tracking mechanisms allow the transmission and storage companies' rates to fluctuate in response to changes in certain operating costs or conditions as they occur to facilitate the timely recovery of its costs incurred. The tracking mechanisms involve a rate adjustment that is filed at a predetermined frequency, typically annually, with the FERC and is subject to regulatory review before new rates go into effect. Other such costs under regulatory tracking mechanisms include upstream pipeline transmission, electric compression, operational purchases and sales of natural gas, and the revenue requirement for capital investments made under Columbia Gas Transmission's long-term plan to modernize its interstate transmission system as discussed above.

Equity Method Investments

Equity Method Investments	6 Months Ended
	Jun. 30, 2015
Equity Method Investments [Abstract]
Equity Method Investments	Equity Method Investments Certain investments of CPG are accounted for under the equity method of accounting. Income and losses from Millennium Pipeline, Hardy Storage and Pennant are reflected in “Equity Earnings in Unconsolidated Affiliates” on the Condensed Statements of Consolidated and Combined Operations (unaudited). These investments are integral to CPG’s business. Contributions are made to these equity investees to fund CPG’s share of capital projects. Columbia Gas Transmission made no contributions to Millennium Pipeline for the three months ended June 30, 2015 and 2014 . Millennium Pipeline distributed $7.6 million and $4.8 million of earnings to Columbia Gas Transmission during the three months ended June 30, 2015 and 2014 , respectively. Columbia Gas Transmission made no contributions to Millennium Pipeline for the six months ended June 30, 2015 and contributed $2.6 million for the six months ended June 30, 2014 . Millennium Pipeline distributed $24.2 million and $11.9 million of earnings to Columbia Gas Transmission during the six months ended June 30, 2015 and 2014 , respectively. No contributions were made to Hardy Storage during the three months ended June 30, 2015 and 2014 . Hardy Storage distributed $0.5 million of earnings to NiSource during each of the three months ended June 30, 2015 and 2014 , respectively. No contributions were made to Hardy Storage during the six months ended June 30, 2015 and 2014 . Hardy Storage distributed $1.0 million of earnings to NiSource during the six months ended June 30, 2015 and 2014 , respectively. No contributions were made to Pennant for the three months ended June 30, 2015 and contributions of $23.8 million were made for the three months ended June 30, 2014 . Pennant distributed $1.5 million of earnings and returned $0.9 million of capital to Columbia Midstream during the three months ended June 30, 2015 . No distributions were received from Pennant during the three months ended June 30, 2014 . No contributions were made to Pennant for the six months ended June 30, 2015 and contributions of $52.2 million were made for the six months ended June 30, 2014 . Pennant distributed $2.7 million of earnings and returned $2.2 million of capital to Columbia Midstream during the six months ended June 30, 2015 . No distributions were received from Pennant during the six months ended June 30, 2014 .

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes CPG’s interim effective tax rates reflect the estimated annual effective tax rates for 2015 and 2014 , adjusted for tax expense associated with certain discrete items. The effective tax rates for the three months ended June 30, 2015 and 2014 were 32.2% and 36.8% , respectively. The effective tax rates for the six months ended June 30, 2015 and 2014 were 33.9% and 37.3% , respectively. The effective tax rate for 2014 differs from the Federal tax rate of 35% primarily due to the effects of tax credits, state income taxes, utility rate-making, and other permanent book-to-tax differences. The effective tax rate for 2015 differs from the Federal tax rate of 35% primarily due to the effects of tax credits, state income taxes, utility rate-making, other permanent book-to-tax differences and income received following CPPL’s IPO that is not subject to income tax at the partnership level. The effective tax rate is impacted by CPPL’s IPO which modified the ownership structure and now reflects CPPL earnings for which the noncontrolling public limited partners are directly responsible for the related income taxes. CPG consolidates the pre-tax income related to the noncontrolling public limited partners’ share of partnership earnings but excludes the related tax provision.

Pension and Other Postretiremen

Pension and Other Postretirement Benefits	6 Months Ended
	Jun. 30, 2015
Pension and Other Postretirement Benefit Expense [Abstract]
Pension and Other Postretirement Benefits	Pension and Other Postretirement Benefits NiSource provides defined contribution plans and noncontributory defined benefit retirement plans that cover employees of CPG. Benefits under the defined benefit retirement plans reflect the employees’ compensation, years of service and age at retirement. Additionally, NiSource provides health care and life insurance benefits for certain retired employees of CPG. The majority of employees may become eligible for these benefits if they reach retirement age while working for CPG. The expected cost of such benefits is accrued during the employees’ years of service. Current rates charged to customers of CPG include postretirement benefit costs. Cash contributions are remitted to grantor trusts. CPG is a participant in the consolidated NiSource defined benefit retirement plans (the Plans), and therefore, CPG is allocated a ratable portion of NiSource’s grantor trusts for the Plans in which its employees and retirees participate. As a result, CPG follows multiple employer accounting under the provisions of GAAP. For the six months ended June 30, 2015 , CPG has made no contributions to its pension plans and contributed $3.0 million to its other postretirement benefit plans. The following table provides the components of CPG's allocation of net periodic benefits cost for the three and six months ended June 30, 2015 and 2014 : Pension Benefits Other Postretirement Benefits Three Months Ended June 30, (in millions) 2015 2014 2015 2014 Predecessor Predecessor Components of Net Periodic Benefit Cost (Income) Service cost $ 1.4 $ 1.2 $ 0.3 $ 0.3 Interest cost 3.5 4.0 1.1 1.1 Expected return on assets (7.0 ) (6.8 ) (4.6 ) (4.1 ) Amortization of prior service credit (0.3 ) (0.3 ) (0.1 ) — Recognized actuarial loss 2.3 1.8 — — Total Net Periodic Benefit Income $ (0.1 ) $ (0.1 ) $ (3.3 ) $ (2.7 ) Pension Benefits Other Postretirement Benefits Six Months Ended June 30, (in millions) 2015 2014 2015 2014 Predecessor Predecessor Components of Net Periodic Benefit Cost (Income) Service cost $ 2.7 $ 2.4 $ 0.6 $ 0.6 Interest cost 7.0 7.9 2.3 2.3 Expected return on assets (14.0 ) (13.7 ) (9.2 ) (8.3 ) Amortization of prior service credit (0.6 ) (0.5 ) (0.3 ) — Recognized actuarial loss 4.7 3.7 — — Total Net Periodic Benefit Income $ (0.2 ) $ (0.2 ) $ (6.6 ) $ (5.4 )

Fair Value

Fair Value	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value	Fair Value CPG has certain financial instruments that are not measured at fair value on a recurring basis but nevertheless are recorded at amounts that approximate fair value due to their liquid or short-term nature, including cash and cash equivalents, customer deposits, short-term borrowings and short-term borrowings-affiliated. CPG's long-term debt and long-term debt-affiliated are recorded at historical amounts. The following methods and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate fair value. Long-term debt and long-term debt-affiliated. The fair values of these securities are estimated based on the quoted market prices for similar issues or on the rates offered for securities of the same remaining maturities. These fair value measurements are classified as Level 2 within the fair value hierarchy. For the six months ended June 30, 2015 and for the year ended December 31, 2014 , there were no changes in the method or significant assumptions used to estimate the fair value of the financial instruments. The carrying amount and estimated fair values of financial instruments were as follows: (in millions) Carrying Amount as of June 30, 2015 Estimated Fair Value as of June 30, 2015 Carrying Amount as of Dec. 31, 2014 Estimated Fair Value as of Dec. 31, 2014 Current portion of long-term debt-affiliated $ — $ — $ 115.9 $ 120.0 Long-term debt 2,745.9 2,723.8 — — Long-term debt-affiliated — — 1,472.8 1,550.4

Other Commitments and Contingen

Other Commitments and Contingencies	6 Months Ended
	Jun. 30, 2015
Other Commitments and Contingencies [Abstract]
Other Commitments and Contingencies	Other Commitments and Contingencies A. Guarantees and Indemnities. In the normal course of its business, CPG and certain subsidiaries enter into various agreements providing financial or performance assurance to third parties on behalf of certain subsidiaries. Such agreements include guarantees and stand-by letters of credit. These agreements are entered into primarily to support or enhance the creditworthiness otherwise attributed to a parent or subsidiary on a stand-alone basis, thereby facilitating the extension of sufficient credit to accomplish the parent or subsidiaries' intended commercial purposes. The total guarantees and indemnities in existence at June 30, 2015 and the years in which they expire were: (in millions) Total 2015 2016 2017 2018 2019 After Guarantees of debt $ 2,750.0 $ — $ — $ — $ 500.0 $ — $ 2,250.0 Lines of credit 20.0 20.0 — — — — — Other guarantees 2.6 — 2.6 — — — — Total commercial commitments $ 2,772.6 $ 20.0 $ 2.6 $ — $ 500.0 $ — $ 2,250.0 Guarantees of Debt. Certain of CPG's subsidiaries, including OpCo GP, Columbia OpCo and CEG have guaranteed payment of $2,750.0 million in aggregated principal amount of CPG's senior notes. Each guarantor of CPG's obligations is required to comply with covenants under the debt indenture and in the event of default the guarantors would be obligated to pay the debt's principal and related interest. CPG does not anticipate its subsidiaries will have any difficulty maintaining compliance. Lines and Letters of Credit. CPPL maintains a $500.0 million senior revolving credit facility, of which $50.0 million is available for issuance of letters of credit. The purpose of the facility is to provide cash for general partnership purposes, including working capital, capital expenditures, and the funding of capital calls. As of June 30, 2015 , CPPL had $20.0 million in outstanding borrowings and no letters of credit under the revolving credit facility. B. Other Legal Proceedings. In the normal course of its business, CPG has been named as a defendant in various legal proceedings. In the opinion of CPG, the ultimate disposition of these currently asserted claims will not have a material impact on CPG’s condensed consolidated and combined financial statements. C. Environmental Matters. CPG’s operations are subject to environmental statutes and regulations related to air quality, water quality, hazardous waste and solid waste. CPG believes that it is in substantial compliance with those environmental regulations currently applicable to its operations and believes that it has all necessary permits to conduct its operations. It is CPG’s continued intent to address environmental issues in cooperation with regulatory authorities in such a manner as to achieve mutually acceptable compliance plans. However, there can be no assurance that CPG will not incur fines and penalties. As of June 30, 2015 and December 31, 2014 , CPG recorded an accrual of approximately $8.8 million and $14.3 million , respectively, to cover environmental remediation at various sites. The current portion of this accrual is included in “Legal and environmental” in the Condensed Consolidated Balance Sheets (unaudited). The noncurrent portion is included in “Other noncurrent liabilities” in the Condensed Consolidated Balance Sheets (unaudited). CPG accrues for costs associated with environmental remediation obligations when the incurrence of such costs is probable and the amounts can be reasonably estimated. The original estimates for cleanup can differ materially from the amount ultimately expended. The actual future expenditures depend on many factors, including currently enacted laws and regulations, the nature and extent of contamination, the method of cleanup, and the availability of cost recovery from customers. As of the date of these financial statements, these expenditures are not estimable at some sites. CPG periodically adjusts its accrual as information is collected and estimates become more refined. Air National Ambient Air Quality Standards . The federal CAA requires the EPA to set NAAQS for particulate matter and five other pollutants considered harmful to public health and the environment. Periodically, the EPA imposes new or modifies existing NAAQS. States that contain areas that do not meet the new or revised standards must take steps to maintain or achieve compliance with the standards. These steps could include additional pollution controls on boilers, engines, turbines, and other facilities owned by electric generation, gas distribution, and gas transmission operations. The following NAAQS were recently added or modified: Ozone : On November 25, 2014, the EPA proposed to lower the 8-hour ozone standard from 75 ppb to within a range of 65-70 ppb. If the standard is finalized and the EPA proceeds with designations, areas where CPG operates currently designated as attainment may be re-classified as non-attainment. CPG will continue to monitor this matter and cannot estimate its impact at this time. Nitrogen Dioxide (NO2) : The EPA revised the NO2 NAAQS by adding a one-hour standard while retaining the annual standard. The new standard could impact some CPG combustion sources. The EPA designated all areas of the country as unclassifiable/attainment in January 2012. After the establishment of a new monitoring network and possible modeling implementation, areas will potentially be re-designated sometime in 2016. States with areas that do not meet the standard will be required to develop rules to bring areas into compliance within five years of designation. Additionally, under certain permitting circumstances, emissions from some existing CPG combustion sources may need to be assessed and mitigated. CPG will continue to monitor this matter and cannot estimate the impact of these rules at this time. Waste CPG has cleanup liabilities associated with some of its former operations. Four sites are associated with its former propane operations and ten sites associated with former petroleum operations. The total liability related to these sites was $6.5 million and $12.5 million at June 30, 2015 and December 31, 2014 , respectively. The liability represents CPG’s best estimate of the cost to remediate the facilities.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	6 Months Ended
	Jun. 30, 2015
Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The following tables display the components of Accumulated Other Comprehensive Loss for the three and six months ended June 30, 2015 and 2014 : Three Months Ended June 30, 2015 (in millions) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of April 1, 2015 $ (14.2 ) $ (10.9 ) $ (25.1 ) Other comprehensive income before reclassifications — 0.3 0.3 Amounts reclassified from accumulated other comprehensive income 0.3 — 0.3 Net current-period other comprehensive income 0.3 0.3 0.6 Balance as of June 30, 2015 $ (13.9 ) $ (10.6 ) $ (24.5 ) Six Months Ended June 30, 2015 (in millions) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of January 1, 2015 $ (16.6 ) $ (17.9 ) $ (34.5 ) Other comprehensive income before reclassifications — 7.2 7.2 Amounts reclassified from accumulated other comprehensive income 0.5 0.1 0.6 Net current-period other comprehensive income 0.5 7.3 7.8 Allocation of accumulated other comprehensive loss to noncontrolling interest 2.2 — 2.2 Balance as of June 30, 2015 $ (13.9 ) $ (10.6 ) $ (24.5 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits. Three Months Ended June 30, 2014 (in millions) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated (1) Predecessor Balance as of April 1, 2014 $ (17.4 ) $ (8.2 ) $ (25.6 ) Other comprehensive income before reclassifications — — — Amounts reclassified from accumulated other comprehensive income 0.3 (0.2 ) 0.1 Net current-period other comprehensive income 0.3 (0.2 ) 0.1 Balance as of June 30, 2014 $ (17.1 ) $ (8.4 ) $ (25.5 ) Six Months Ended June 30, 2014 (in millions) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Predecessor Balance as of January 1, 2014 $ (17.6 ) $ (8.2 ) $ (25.8 ) Other comprehensive income before reclassifications — — — Amounts reclassified from accumulated other comprehensive income 0.5 (0.2 ) 0.3 Net current-period other comprehensive (loss) income 0.5 (0.2 ) 0.3 Balance as of June 30, 2014 $ (17.1 ) $ (8.4 ) $ (25.5 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits. Equity Investment Millennium Pipeline is an equity method investment, and, therefore, CPG is required to recognize a proportional share of Millennium Pipeline’s OCI. The remaining unrecognized loss at June 30, 2015 of $13.9 million , after tax, related to terminated interest rate swaps is being amortized over the period ending June 2025 into earnings using the effective interest method through interest expense as interest payments are made by Millennium Pipeline. The unrecognized loss of $13.9 million , after tax, and $16.6 million , after tax, at June 30, 2015 and December 31, 2014 , respectively, is included in gains and losses on cash flow hedges above.

Other, Net

Other, Net	6 Months Ended
	Jun. 30, 2015
Other Income and Expenses [Abstract]
Other, Net	Other, Net Three Months Ended Six Months Ended (in millions) 2015 2014 2015 2014 Predecessor Predecessor AFUDC Equity $ 5.0 $ 2.7 $ 8.5 $ 4.3 Miscellaneous 0.3 — 1.4 0.3 Total Other, net $ 5.3 $ 2.7 $ 9.9 $ 4.6

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	6 Months Ended
	Jun. 30, 2015
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information The following table provides additional information regarding CPG’s Condensed Statements of Consolidated and Combined Cash Flows (unaudited) for the six months ended June 30, 2015 and 2014 : (in millions) 2015 2014 Predecessor Supplemental Disclosures of Cash Flow Information Non-cash transactions: Capital expenditures included in current liabilities (1) $ 184.5 $ 94.0 Schedule of interest and income taxes paid: Cash paid for interest, net of interest capitalized amounts $ 39.7 $ 21.4 Cash paid for income taxes 27.8 34.4 (1) Capital expenditures included in current liabilities is comprised of "Accrued capital expenditures" and certain other amounts included within "Accounts payable" on the Condensed Consolidated Balance Sheet (unaudited).

Concentration of Credit Risk

Concentration of Credit Risk	6 Months Ended
	Jun. 30, 2015
Risks and Uncertainties [Abstract]
Concentration Risk Disclosure	Concentration of Credit Risk Columbia Gas of Ohio, an affiliated party, accounted for greater than 10% of total operating revenues for the three and six months ended June 30, 2015 and 2014 . The following tables provide the customer's operating revenues and percentage of total operating revenues for the three and six months ended June 30, 2015 and 2014 : Three Months Ended June 30, 2015 2014 (in millions) Total Operating Revenues Percentage of Total Operating Revenues Total Operating Revenues Percentage of Total Operating Revenues Predecessor Columbia Gas of Ohio (1) $ 36.2 11.5 % $ 36.0 10.5 % Six Months Ended June 30, 2015 2014 (in millions) Total Operating Revenues Percentage of Total Operating Revenues Total Operating Revenues Percentage of Total Operating Revenues Predecessor Columbia Gas of Ohio (1) $ 85.1 13.0 % $ 83.6 12.1 % (1) Represents the gross amount of revenue contracted for with Columbia Gas of Ohio and, therefore, subject to risk at the loss of this customer. Columbia Gas of Ohio has entered into certain capacity release arrangements with third parties which ultimately can decrease the net revenue amount we receive from Columbia Gas of Ohio in any given period. There was no other single customer that accounted for greater than 10% of operating revenues for the three and six months ended June 30, 2015 and 2014 . The loss of a significant portion of operating revenues from this customer would have a material adverse effect on the business of CPG.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2015
Subsequent Events [Abstract]
Subsequent Events [Text Block]	Subsequent Events Separation. On June 2, 2015 , NiSource's board of directors approved the distribution of all the shares of CPG common stock to holders of NiSource common stock. In order to allow NiSource to effect the Separation, CPG requested, and the SEC declared effective, the registration statement on Form 10 on June 2, 2015 . In May 2015, CPG received approximately $2,722.2 million of cash from the private placement of senior notes, then used a portion of those proceeds to repay approximately $1,087.3 million of intercompany debt and short-term borrowings, net of amounts due from the money pool, between CPG and NiSource and make a cash distribution of approximately $1,450.0 million to NiSource. On July 1, 2015 , NiSource distributed 317.6 million shares, one share of CPG common stock for every one share of NiSource common stock held by NiSource shareholders of record as of the close of business on June 19, 2015 , the record date of the distribution. At the close of business on July 1, 2015 , CPG became an independent, publicly traded company as a result of the distribution. CPG's common stock began trading "regular-way" under the ticker symbol "CPGX" on the NYSE on July 2, 2015 . Gain on Conveyances. On December 29, 2014, CEVCO finalized an agreement with CNX Gas Company LLC, a wholly owned subsidiary of CONSOL Energy, to lease approximately 20,000 acres of Utica Shale and Upper Devonian gas rights in Greene and Washington Counties in Pennsylvania and Marshall and Ohio Counties in West Virginia. Under the terms of the agreement, on July 1, 2015, CEVCO conveyed acres to CNX resulting in a bonus payment of $35.8 million . This amount will be recorded as a gain on conveyances in the third quarter of 2015.

CPPL Initial Public Offering (T

CPPL Initial Public Offering (Tables)	6 Months Ended
	Jun. 30, 2015
Equity [Abstract]
Change From Net Income Attributable to the Partnership and Transfers to Noncontrolling Interest	Three Months Ended Six Months Ended (in millions) 2015 2015 Net income attributable to CPG $ 50.8 $ 140.8 Increase in CPG’s net parent investment for the sale of 8.4% of Columbia OpCo — 227.1 Change from net income attributable to CPG and transfers to noncontrolling interest $ 50.8 $ 367.9

Transactions with Affiliates (T

Transactions with Affiliates (Tables)	6 Months Ended
	Jun. 30, 2015
Related Party Transactions [Abstract]
Schedule of Transactions with Affiliates	Statement of Operations. Three Months Ended Six Months Ended (in millions) 2015 2014 2015 2014 Predecessor Predecessor Transportation revenues $ 18.5 $ 18.8 $ 47.5 $ 47.4 Storage revenues 12.9 13.2 26.2 26.9 Other revenues 0.1 0.1 0.2 0.2 Operation and maintenance expense 24.9 29.3 52.9 57.8 Interest expense 11.0 12.6 29.3 24.7 Interest income 3.4 0.2 4.4 0.3 Balance Sheet. (in millions) June 30, 2015 December 31, 2014 Accounts receivable $ 678.8 $ 180.0 Current portion of long-term debt — 115.9 Short-term borrowings 718.9 252.5 Accounts payable 29.6 53.6 Long-term debt — 1,472.8
Schedule of Related Party Transactions, Long-Term Debt	Origination Date Interest Rate Maturity Date June 30, 2015 December 31, 2014 (in millions) Predecessor November 28, 2005 (1) 5.41 % November 30, 2015 $ — $ 115.9 November 28, 2005 5.45 % November 28, 2016 — 45.3 November 28, 2005 5.92 % November 28, 2025 — 133.5 November 28, 2012 4.63 % November 28, 2032 — 45.0 November 28, 2012 4.94 % November 30, 2037 — 95.0 December 19, 2012 5.16 % December 21, 2037 — 55.0 November 28, 2012 5.26 % November 28, 2042 — 170.0 December 19, 2012 5.49 % December 18, 2042 — 95.0 December 9, 2013 (2) 4.75 % December 31, 2016 — 834.0 Total Long-term Debt $ — $ 1,588.7

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	6 Months Ended
	Jun. 30, 2015
Asset Retirement Obligation [Abstract]
Changes In Company's Liability for Asset Retirement Obligations	(in millions) 2015 2014 Predecessor Balance as of January 1, $ 23.2 $ 26.3 Accretion expense 0.6 0.8 Additions 0.4 2.0 Settlements — — Change in estimated cash flows — (0.2 ) Balance as of June 30, $ 24.2 $ 28.9 CPG's asset retirement obligations above relate to the modernization program of pipelines and transmission facilities, the retiring of offshore facilities, polychlorinated biphenyl ("PCB") remediation and asbestos removal at several compressor and measuring stations. CPG recognizes that there are obligations to incur significant costs to retire wells associated with gas storage operations; however, the lives of these wells are indeterminable until management establishes plans for closure.

Pension and Other Postretirem33

Pension and Other Postretirement Benefits (Tables)	6 Months Ended
	Jun. 30, 2015
Pension and Other Postretirement Benefit Expense [Abstract]
Components Of The Plans' Net Periodic Benefits Cost	Pension Benefits Other Postretirement Benefits Three Months Ended June 30, (in millions) 2015 2014 2015 2014 Predecessor Predecessor Components of Net Periodic Benefit Cost (Income) Service cost $ 1.4 $ 1.2 $ 0.3 $ 0.3 Interest cost 3.5 4.0 1.1 1.1 Expected return on assets (7.0 ) (6.8 ) (4.6 ) (4.1 ) Amortization of prior service credit (0.3 ) (0.3 ) (0.1 ) — Recognized actuarial loss 2.3 1.8 — — Total Net Periodic Benefit Income $ (0.1 ) $ (0.1 ) $ (3.3 ) $ (2.7 ) Pension Benefits Other Postretirement Benefits Six Months Ended June 30, (in millions) 2015 2014 2015 2014 Predecessor Predecessor Components of Net Periodic Benefit Cost (Income) Service cost $ 2.7 $ 2.4 $ 0.6 $ 0.6 Interest cost 7.0 7.9 2.3 2.3 Expected return on assets (14.0 ) (13.7 ) (9.2 ) (8.3 ) Amortization of prior service credit (0.6 ) (0.5 ) (0.3 ) — Recognized actuarial loss 4.7 3.7 — — Total Net Periodic Benefit Income $ (0.2 ) $ (0.2 ) $ (6.6 ) $ (5.4 )

Fair Value (Tables)

Fair Value (Tables)	6 Months Ended
	Jun. 30, 2015
Fair Value Disclosures [Abstract]
Carrying Amount And Estimated Fair Values Of Financial Instruments	(in millions) Carrying Amount as of June 30, 2015 Estimated Fair Value as of June 30, 2015 Carrying Amount as of Dec. 31, 2014 Estimated Fair Value as of Dec. 31, 2014 Current portion of long-term debt-affiliated $ — $ — $ 115.9 $ 120.0 Long-term debt 2,745.9 2,723.8 — — Long-term debt-affiliated — — 1,472.8 1,550.4

Other Commitments and Conting35

Other Commitments and Contingencies Other Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Contractual Obligation, Fiscal Year Maturity Schedule	The total guarantees and indemnities in existence at June 30, 2015 and the years in which they expire were: (in millions) Total 2015 2016 2017 2018 2019 After Guarantees of debt $ 2,750.0 $ — $ — $ — $ 500.0 $ — $ 2,250.0 Lines of credit 20.0 20.0 — — — — — Other guarantees 2.6 — 2.6 — — — — Total commercial commitments $ 2,772.6 $ 20.0 $ 2.6 $ — $ 500.0 $ — $ 2,250.0

Accumulated Other Comprehensi36

Accumulated Other Comprehensive Loss (Tables)	6 Months Ended
	Jun. 30, 2015
Other Comprehensive Income (Loss), Tax [Abstract]
Components Of Accumulated Other Comprehensive Loss	Three Months Ended June 30, 2015 (in millions) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of April 1, 2015 $ (14.2 ) $ (10.9 ) $ (25.1 ) Other comprehensive income before reclassifications — 0.3 0.3 Amounts reclassified from accumulated other comprehensive income 0.3 — 0.3 Net current-period other comprehensive income 0.3 0.3 0.6 Balance as of June 30, 2015 $ (13.9 ) $ (10.6 ) $ (24.5 ) Six Months Ended June 30, 2015 (in millions) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of January 1, 2015 $ (16.6 ) $ (17.9 ) $ (34.5 ) Other comprehensive income before reclassifications — 7.2 7.2 Amounts reclassified from accumulated other comprehensive income 0.5 0.1 0.6 Net current-period other comprehensive income 0.5 7.3 7.8 Allocation of accumulated other comprehensive loss to noncontrolling interest 2.2 — 2.2 Balance as of June 30, 2015 $ (13.9 ) $ (10.6 ) $ (24.5 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits. Three Months Ended June 30, 2014 (in millions) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated (1) Predecessor Balance as of April 1, 2014 $ (17.4 ) $ (8.2 ) $ (25.6 ) Other comprehensive income before reclassifications — — — Amounts reclassified from accumulated other comprehensive income 0.3 (0.2 ) 0.1 Net current-period other comprehensive income 0.3 (0.2 ) 0.1 Balance as of June 30, 2014 $ (17.1 ) $ (8.4 ) $ (25.5 ) Six Months Ended June 30, 2014 (in millions) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Predecessor Balance as of January 1, 2014 $ (17.6 ) $ (8.2 ) $ (25.8 ) Other comprehensive income before reclassifications — — — Amounts reclassified from accumulated other comprehensive income 0.5 (0.2 ) 0.3 Net current-period other comprehensive (loss) income 0.5 (0.2 ) 0.3 Balance as of June 30, 2014 $ (17.1 ) $ (8.4 ) $ (25.5 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits.

Other, Net (Tables)

Other, Net (Tables)	6 Months Ended
	Jun. 30, 2015
Other Income and Expenses [Abstract]
Schedule Of Other, Net	Three Months Ended Six Months Ended (in millions) 2015 2014 2015 2014 Predecessor Predecessor AFUDC Equity $ 5.0 $ 2.7 $ 8.5 $ 4.3 Miscellaneous 0.3 — 1.4 0.3 Total Other, net $ 5.3 $ 2.7 $ 9.9 $ 4.6

Supplemental Cash Flow Inform38

Supplemental Cash Flow Information (Tables)	6 Months Ended
	Jun. 30, 2015
Supplemental Cash Flow Information [Abstract]
Additional Information Regarding Condensed Statements of Consolidated and Combined Cash Flows	(in millions) 2015 2014 Predecessor Supplemental Disclosures of Cash Flow Information Non-cash transactions: Capital expenditures included in current liabilities (1) $ 184.5 $ 94.0 Schedule of interest and income taxes paid: Cash paid for interest, net of interest capitalized amounts $ 39.7 $ 21.4 Cash paid for income taxes 27.8 34.4 (1) Capital expenditures included in current liabilities is comprised of "Accrued capital expenditures" and certain other amounts included within "Accounts payable" on the Condensed Consolidated Balance Sheet (unaudited).

Concentration of Credit Risk (T

Concentration of Credit Risk (Tables)	6 Months Ended
	Jun. 30, 2015
Risks and Uncertainties [Abstract]
Schedule of Concentration Of Credit Risk	The following tables provide the customer's operating revenues and percentage of total operating revenues for the three and six months ended June 30, 2015 and 2014 : Three Months Ended June 30, 2015 2014 (in millions) Total Operating Revenues Percentage of Total Operating Revenues Total Operating Revenues Percentage of Total Operating Revenues Predecessor Columbia Gas of Ohio (1) $ 36.2 11.5 % $ 36.0 10.5 % Six Months Ended June 30, 2015 2014 (in millions) Total Operating Revenues Percentage of Total Operating Revenues Total Operating Revenues Percentage of Total Operating Revenues Predecessor Columbia Gas of Ohio (1) $ 85.1 13.0 % $ 83.6 12.1 % (1) Represents the gross amount of revenue contracted for with Columbia Gas of Ohio and, therefore, subject to risk at the loss of this customer. Columbia Gas of Ohio has entered into certain capacity release arrangements with third parties which ultimately can decrease the net revenue amount we receive from Columbia Gas of Ohio in any given period.

Basis of Accounting Presentat40

Basis of Accounting Presentation (Details)	Jun. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Pipeline Miles	15,000

CPPL Initial Public Offering (N

CPPL Initial Public Offering (Narrative) (Details) - Jun. 30, 2015 - USD ($) $ in Millions	Total	Total
Initial Public Offering [Line Items]
Issuance of common units of CPPL	$ 1,168.4	$ 1,168.4
Columbia Pipeline Partners LP [Member]
Initial Public Offering [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	53.50%
Columbia OpCo
Initial Public Offering [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Additional Ownership Interest	8.40%
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	15.70%
Reimbursement of Preformation Capital	$ 500
Noncontrolling Interest [Member]
Initial Public Offering [Line Items]
Issuance of common units of CPPL		$ 1,168.4
Common Units [Member]
Initial Public Offering [Line Items]
Partners' Capital Account, Units, Sold in Public Offering	53,833,107

CPPL Initial Public Offering (S

CPPL Initial Public Offering (Schedule of Change From Net Income Attributable to the Partnership and Transfers to Noncontrolling Interest) (Details) - Jun. 30, 2015 - USD ($) $ in Millions	Total	Total	Total
Initial Public Offering [Line Items]
Net Income (Loss) Attributable to Parent	$ 50.8	$ 140.8	$ 140.8
Noncontrolling Interest, Increase from Subsidiary Equity Issuance			4.9
Change from net income attributable to the Partnership and transfers to noncontrolling interest	50.8	367.9
Noncontrolling Interest [Member]
Initial Public Offering [Line Items]
Noncontrolling Interest, Increase from Subsidiary Equity Issuance	$ 0	$ 227.1	$ 4.9

Transactions with Affiliates (N

Transactions with Affiliates (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		5 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014	Dec. 05, 2014
Related Party Transaction [Line Items]
Interest Expense, Long-term Debt	$ 12			$ 31
Allowance for Funds Used During Construction, Capitalized Interest	$ 1.4			$ 2.4
Short-term Debt, Weighted Average Interest Rate	1.21%		1.21%	1.21%
Interest Expense, Short-term Borrowings	$ 0.4			$ 0.7
Accounts receivable-affiliated	678.8		$ 678.8	678.8		$ 180
Revolving credit facility	2,600		2,600	2,600
Short-term Debt	20		20	20		0
Default Provision Floor	50		50	50
Short-term borrowings-affiliated	718.9		718.9	718.9		252.5
Distribution to Parent				1,450
Repayments of Related Party Debt				1,087.3
Transportation and Storage Services
Related Party Transaction [Line Items]
Accounts receivable-affiliated	32.9		32.9	32.9		28.8
Predecessor [Member]
Related Party Transaction [Line Items]
Interest Expense, Long-term Debt		$ 13.9			$ 26.1
Allowance for Funds Used During Construction, Capitalized Interest		$ 2			$ 3.2
Short-term Debt, Weighted Average Interest Rate		0.64%			0.64%
Interest Expense, Short-term Borrowings		$ 0.7			$ 1.8
Columbia OpCo
Related Party Transaction [Line Items]
Reimbursement of Preformation Capital			500
Money Pool
Related Party Transaction [Line Items]
Accounts receivable-affiliated	645.9		645.9	645.9		$ 125
Revolving credit facility	750		750	750
Revolving Credit Facility
Related Party Transaction [Line Items]
Revolving credit facility	$ 1,500		$ 1,500	$ 1,500			$ 1,500
Notes Due 2016 [1]
Related Party Transaction [Line Items]
Debt Instrument, Maturity Date				Dec. 31, 2016
London Interbank Offered Rate (LIBOR)
Related Party Transaction [Line Items]
Basis Spread on Variable Rate				1.00%
London Interbank Offered Rate (LIBOR) | Notes Due 2016 [1]
Related Party Transaction [Line Items]
Basis Spread on Variable Rate				1.50%

Transactions with Affiliates (S

Transactions with Affiliates (Schedule of Affiliated Transactions) (Details) - Related Party Transaction [Domain] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Related Party Transaction [Line Items]
Transportation revenues-affiliated	$ 18.5		$ 47.5
Storage revenues	12.9		26.2
Other revenues	0.1		0.2
Operation and maintenance-affiliated	24.9		52.9
Interest expense	11		29.3
Interest income	3.4		4.4
Accounts receivable	678.8		678.8		$ 180
Current portion of long-term debt	0		0		115.9
Short-term borrowings-affiliated	718.9		718.9		252.5
Accounts payable	29.6		29.6		53.6
Long-term debt-affiliated	$ 0		$ 0		$ 1,472.8
Predecessor [Member]
Related Party Transaction [Line Items]
Transportation revenues-affiliated		$ 18.8		$ 47.4
Storage revenues		13.2		26.9
Other revenues		0.1		0.2
Operation and maintenance-affiliated		29.3		57.8
Interest expense		12.6		24.7
Interest income		$ 0.2		$ 0.3

Transactions with Affiliates 45

Transactions with Affiliates (Schedule of Long-term Debt) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Long-term Debt	$ 0
Notes Due 2015
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Debt Instrument, Issuance Date	Nov. 28, 2005
Debt Instrument, Interest Rate, Stated Percentage	5.41%
Debt Instrument, Maturity Date	Nov. 30, 2015
Long-term Debt	$ 0
Notes Due 2016
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Debt Instrument, Issuance Date	Nov. 28, 2005
Debt Instrument, Interest Rate, Stated Percentage	5.45%
Debt Instrument, Maturity Date	Nov. 28, 2016
Long-term Debt	$ 0
Notes Due 2025
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Debt Instrument, Issuance Date	Nov. 28, 2005
Debt Instrument, Interest Rate, Stated Percentage	5.92%
Debt Instrument, Maturity Date	Nov. 28, 2025
Long-term Debt	$ 0
Notes Due 2032
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Debt Instrument, Issuance Date	Nov. 28, 2012
Debt Instrument, Interest Rate, Stated Percentage	4.63%
Debt Instrument, Maturity Date	Nov. 28, 2032
Long-term Debt	$ 0
Notes Due 2037
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Debt Instrument, Issuance Date	Nov. 28, 2012
Debt Instrument, Interest Rate, Stated Percentage	4.94%
Debt Instrument, Maturity Date	Nov. 30, 2037
Long-term Debt	$ 0
Notes Due 2037 [1]
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Debt Instrument, Issuance Date	Dec. 19, 2012
Debt Instrument, Interest Rate, Stated Percentage	5.16%
Debt Instrument, Maturity Date	Dec. 21, 2037
Long-term Debt	$ 0
Notes Due 2042
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Debt Instrument, Issuance Date	Nov. 28, 2012
Debt Instrument, Interest Rate, Stated Percentage	5.26%
Debt Instrument, Maturity Date	Nov. 28, 2042
Long-term Debt	$ 0
Notes Due 2042 [1]
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Debt Instrument, Issuance Date	Dec. 19, 2012
Debt Instrument, Interest Rate, Stated Percentage	5.49%
Debt Instrument, Maturity Date	Dec. 18, 2042
Long-term Debt	$ 0
Notes Due 2016 [1]
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Debt Instrument, Issuance Date	Dec. 9, 2013
Debt Instrument, Interest Rate, Stated Percentage	4.75%
Debt Instrument, Maturity Date	Dec. 31, 2016
Long-term Debt	$ 0
Predecessor [Member]
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Long-term Debt		$ 1,588.7
Predecessor [Member] | Notes Due 2015
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Long-term Debt		115.9
Predecessor [Member] | Notes Due 2016
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Long-term Debt		45.3
Predecessor [Member] | Notes Due 2025
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Long-term Debt		133.5
Predecessor [Member] | Notes Due 2032
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Long-term Debt		45
Predecessor [Member] | Notes Due 2037
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Long-term Debt		95
Predecessor [Member] | Notes Due 2037 [1]
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Long-term Debt		55
Predecessor [Member] | Notes Due 2042
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Long-term Debt		170
Predecessor [Member] | Notes Due 2042 [1]
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Long-term Debt		95
Predecessor [Member] | Notes Due 2016 [1]
Schedule of Related Party Transactions, Long-Term Debt [Line Items]
Long-term Debt		$ 834

Short-Term Borrowings (Narrativ

Short-Term Borrowings (Narrative) (Details) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2015USD ($)$ / shares	Dec. 05, 2014USD ($)
Short-term Debt [Line Items]
Revolving credit facility	$ 2,600
Funds Used to Support Columbia OpCo		$ 750
Funds to Support General Purposes		750
Default Provision Floor	50
CPPL
Short-term Debt [Line Items]
Default Provision Floor	$ 50
Minimum
Short-term Debt [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.125%
Distribution Policy, Minimum | $ / shares	$ 0.1675
Maximum
Short-term Debt [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.35%
Ratio of Indebtedness to Net Capital	1
Line of Credit
Short-term Debt [Line Items]
Long-term Line of Credit	$ 0
Line of Credit | CPPL
Short-term Debt [Line Items]
Long-term Line of Credit	20
Revolving Credit Facility
Short-term Debt [Line Items]
Revolving credit facility	1,500	1,500
Letters of Credit Outstanding	0
Revolving Credit Facility | CPPL
Short-term Debt [Line Items]
Revolving credit facility	500	$ 500
Letters of Credit Outstanding	0
Letter of Credit
Short-term Debt [Line Items]
Revolving credit facility	250
Letter of Credit | CPPL
Short-term Debt [Line Items]
Revolving credit facility	$ 50
Period 1 | Minimum
Short-term Debt [Line Items]
Ratio of Indebtedness to Net Capital	5.75
Period 1 | Maximum
Short-term Debt [Line Items]
Ratio of Indebtedness to Net Capital	1
Period 2 | Minimum
Short-term Debt [Line Items]
Ratio of Indebtedness to Net Capital	5.50
Period 2 | Maximum
Short-term Debt [Line Items]
Ratio of Indebtedness to Net Capital	1
Period 3 | Minimum
Short-term Debt [Line Items]
Ratio of Indebtedness to Net Capital	5
Acquisition Period | Minimum
Short-term Debt [Line Items]
Ratio of Indebtedness to Net Capital	5.50
Acquisition Period | Maximum
Short-term Debt [Line Items]
Ratio of Indebtedness to Net Capital	1
Federal Funds Effective Swap Rate
Short-term Debt [Line Items]
Basis Spread on Variable Rate	0.50%
Federal Funds Effective Swap Rate | Minimum
Short-term Debt [Line Items]
Margin Rate	0.00%
Federal Funds Effective Swap Rate | Maximum
Short-term Debt [Line Items]
Margin Rate	0.65%
London Interbank Offered Rate (LIBOR)
Short-term Debt [Line Items]
Basis Spread on Variable Rate	1.00%
London Interbank Offered Rate (LIBOR) | Minimum
Short-term Debt [Line Items]
Margin Rate	0.00%
London Interbank Offered Rate (LIBOR) | Maximum
Short-term Debt [Line Items]
Margin Rate	0.65%
Eurodollar
Short-term Debt [Line Items]
Margin Rate	1.00%
Eurodollar | Minimum
Short-term Debt [Line Items]
Margin Rate	1.00%
Eurodollar | Maximum
Short-term Debt [Line Items]
Margin Rate	1.65%

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions	May. 22, 2015	Jun. 30, 2015
Debt Instrument [Line Items]
Senior Notes		$ 2,722.2
Notes Due 2025
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		5.92%
Debt Instrument, Issuance Date		Nov. 28, 2005
Debt Instrument, Maturity Date		Nov. 28, 2025
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 2,750
Debt Instrument, Issuance Date	May 22, 2015
Senior Notes [Member] | Notes Due 2018
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500
Debt Instrument, Interest Rate, Stated Percentage	2.45%
Debt Instrument, Maturity Date	Jun. 1, 2018
Senior Notes [Member] | Notes Due 2020
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 750
Debt Instrument, Interest Rate, Stated Percentage	3.30%
Debt Instrument, Maturity Date	Jun. 1, 2020
Senior Notes [Member] | Notes Due 2025
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 1,000
Debt Instrument, Interest Rate, Stated Percentage	4.50%
Debt Instrument, Maturity Date	Jun. 1, 2025
Senior Notes [Member] | Notes Due 2045
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500
Debt Instrument, Interest Rate, Stated Percentage	5.80%
Debt Instrument, Maturity Date	Jun. 1, 2045

Gain on Sale of Assets (Narrati

Gain on Sale of Assets (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Gain On Sale of Assets [Abstract]
Gain on Conveyances	$ 8.3	$ 0.3	$ 13.6	$ 17.8
Deferred Gains On Conveyances	$ 10.9		$ 10.9		$ 19.6

Goodwill (Narrative) (Details)

Goodwill (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill	$ 1,975.5	$ 1,975.5

Asset Retirement Obligations (C

Asset Retirement Obligations (Changes In Company's Liability For Asset Retirement Obligations) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Beginning Balance	$ 23.2
Accretion expense	0.6
Additions	0.4
Settlements	0
Change in estimated cash flows	0
Ending Balance	$ 24.2
Predecessor [Member]
Beginning Balance		$ 26.3
Accretion expense		0.8
Additions		2
Settlements		0
Change in estimated cash flows		(0.2)
Ending Balance		$ 28.9

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions	Jan. 01, 2015	Feb. 01, 2015
Regulatory Assets and Liabilities Disclosure [Abstract]
Expected Modernization Investment	$ 300
Modernization Program Recovery		$ 320

Equity Method Investments (Narr

Equity Method Investments (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Millennium Pipeline
Schedule of Equity Method Investments [Line Items]
Contributions	$ 0	$ 0	$ 0	$ 2.6
Distributions	7.6	4.8	24.2	11.9
Hardy Storage [Member]
Schedule of Equity Method Investments [Line Items]
Contributions	0	0	0	0
Distributions	0.5	0.5	1	1
Pennant [Member]
Schedule of Equity Method Investments [Line Items]
Contributions	0	23.8	0	52.2
Distributions	1.5	$ 0	2.7	$ 0
Proceeds from Equity Method Investment, Dividends or Distributions, Return of Capital	$ 0.9		$ 2.2

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Taxes [Line Items]
Effective income tax rates	32.20%	36.80%	33.90%	37.30%
Corporate Income Tax Rate			35.00%

Pension and Other Postretirem54

Pension and Other Postretirement Benefits (Narrative) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2015USD ($)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 3

Pension and Other Postretirem55

Pension and Other Postretirement Benefits (Components Of The Plans' Net Periodic Benefits Cost) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 1.4		$ 2.7
Interest cost	3.5		7
Expected return on assets	(7)		(14)
Amortization of prior service credit	(0.3)		(0.6)
Recognized actuarial loss	2.3		4.7
Total Net Periodic Benefits Cost	(0.1)		(0.2)
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	0.3		0.6
Interest cost	1.1		2.3
Expected return on assets	(4.6)		(9.2)
Amortization of prior service credit	(0.1)		(0.3)
Recognized actuarial loss	0		0
Total Net Periodic Benefits Cost	$ (3.3)		$ (6.6)
Predecessor [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		$ 1.2		$ 2.4
Interest cost		4		7.9
Expected return on assets		(6.8)		(13.7)
Amortization of prior service credit		(0.3)		(0.5)
Recognized actuarial loss		1.8		3.7
Total Net Periodic Benefits Cost		(0.1)		(0.2)
Predecessor [Member] | Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost		0.3		0.6
Interest cost		1.1		2.3
Expected return on assets		(4.1)		(8.3)
Amortization of prior service credit		0		0
Recognized actuarial loss		0		0
Total Net Periodic Benefits Cost		$ (2.7)		$ (5.4)

Fair Value (Carrying Amount And

Fair Value (Carrying Amount And Estimated Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Current portion of long-term debt	$ 0	$ 115.9
Current Portion of Long Term Debt, Fair Value	0	120
Long-term Debt, Carrying amount	2,745.9	0
Long-term Debt, Estimated Fair Value	2,723.8	0
Long-term Debt-affiliated, Carrying Amount	0	1,472.8
Long-term Debt-affiliated, Estimated Fair Value	$ 0	$ 1,550.4

Other Commitments and Conting57

Other Commitments and Contingencies Other Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2015	May. 22, 2015	Dec. 31, 2014	Dec. 05, 2014
Other Commitments [Line Items]
Revolving credit facility	$ 2,600
Accrual for Environmental Loss Contingencies	8.8		$ 14.3
Liability for Estimated Remediation Costs	6.5		$ 12.5
Revolving Credit Facility
Other Commitments [Line Items]
Revolving credit facility	1,500			$ 1,500
Letters of Credit Outstanding	0
Line of Credit
Other Commitments [Line Items]
Long-term Line of Credit	0
Letter of Credit
Other Commitments [Line Items]
Revolving credit facility	250
CPPL | Revolving Credit Facility
Other Commitments [Line Items]
Revolving credit facility	500			$ 500
Letters of Credit Outstanding	0
CPPL | Line of Credit
Other Commitments [Line Items]
Long-term Line of Credit	20
CPPL | Letter of Credit
Other Commitments [Line Items]
Revolving credit facility	$ 50
Senior Notes [Member]
Other Commitments [Line Items]
Debt Instrument, Face Amount		$ 2,750

Other Commitments and Conting58

Other Commitments and Contingencies (Existence and Expiration of Commercial Commitments) (Details) $ in Millions	Jun. 30, 2015USD ($)
Other Commitments and Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 2,772.6
Guarantee Obligations Maximum Exposure Year One	20
Guarantee Obligations Maximum Exposure Year Two	2.6
Guarantee Obligations Maximum Exposure Year Three	0
Guarantee Obligations Maximum Exposure Year Four	500
Guarantee Obligations Maximum Exposure Year Five	0
Guarantee Obligations Maximum Exposure Thereafter	2,250
Guarantee of Indebtedness of Others [Member]
Other Commitments and Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	2,750
Guarantee Obligations Maximum Exposure Year One	0
Guarantee Obligations Maximum Exposure Year Two	0
Guarantee Obligations Maximum Exposure Year Three	0
Guarantee Obligations Maximum Exposure Year Four	500
Guarantee Obligations Maximum Exposure Year Five	0
Guarantee Obligations Maximum Exposure Thereafter	2,250
Lines of Credit
Other Commitments and Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	20
Guarantee Obligations Maximum Exposure Year Two	0
Guarantee Obligations Maximum Exposure Year Three	0
Guarantee Obligations Maximum Exposure Year Four	0
Guarantee Obligations Maximum Exposure Year Five	0
Guarantee Obligations Maximum Exposure Thereafter	0
Guarantee Type, Other [Member]
Other Commitments and Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	2.6
Guarantee Obligations Maximum Exposure Year One	0
Guarantee Obligations Maximum Exposure Year Two	2.6
Guarantee Obligations Maximum Exposure Year Three	0
Guarantee Obligations Maximum Exposure Year Four	0
Guarantee Obligations Maximum Exposure Year Five	0
Guarantee Obligations Maximum Exposure Thereafter	0
Line of Credit
Other Commitments and Contingencies [Line Items]
Long-term Line of Credit	0
CPPL | Line of Credit
Other Commitments and Contingencies [Line Items]
Long-term Line of Credit	$ 20

Accumulated Other Comprehensi59

Accumulated Other Comprehensive Loss (Narrative) (Details) - Long-term Debt, Type [Domain] - Millennium Pipeline - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Loss [Line Items]
Other Comprehensive Income Unrecognized Gain Loss On Derivatives Arising During Period Net Of Tax	$ 13.9	$ 16.6
Debt Instrument, Maturity Date	Jun. 1, 2025

(Components Of Accumulated Othe

(Components Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	$ (25.1)	$ (25.6)	$ (34.5)	$ (25.8)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]	0.3	0	7.2	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	0.3	0.1	0.6	0.3
Other Comprehensive Income (Loss), Net of Tax	[1]	0.6	0.1	7.8	0.3
Allocation of Accumulated Other Comprehensive Loss To Noncontrolling Interest				0
Ending Balance	[1]	(24.5)	(25.5)	(24.5)	(25.5)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(14.2)	(17.4)	(16.6)	(17.6)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]	0	0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	0.3	0.3	0.5	0.5
Other Comprehensive Income (Loss), Net of Tax	[1]	0.3	0.3	0.5	0.5
Allocation of Accumulated Other Comprehensive Loss To Noncontrolling Interest	[1]			2.2
Ending Balance	[1]	(13.9)	(17.1)	(13.9)	(17.1)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(10.9)	(8.2)	(17.9)	(8.2)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]	0.3	0	7.2	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	0	(0.2)	0.1	(0.2)
Other Comprehensive Income (Loss), Net of Tax	[1]	0.3	(0.2)	7.3	(0.2)
Allocation of Accumulated Other Comprehensive Loss To Noncontrolling Interest	[1]			0
Ending Balance	[1]	$ (10.6)	$ (8.4)	(10.6)	$ (8.4)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Net of Tax				7.8
Allocation of Accumulated Other Comprehensive Loss To Noncontrolling Interest				$ 2.2
[1]	All amounts are net of tax. Amounts in parentheses indicate debits.

Other, Net (Schedule of Other,

Other, Net (Schedule of Other, Net) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule Of Other, Net [Line Items]
AFUDC Equity	$ 5		$ 8.5
Miscellaneous	0.3		1.4
Total Other, net	$ 5.3		$ 9.9
Predecessor [Member]
Schedule Of Other, Net [Line Items]
AFUDC Equity		$ 2.7		$ 4.3
Miscellaneous		0		0.3
Total Other, net		$ 2.7		$ 4.6

Supplemental Cash Flow Inform62

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014
Supplemental Cash Flow [Line Items]
Capital expenditures included in current liabilities	[1]	$ 184.5	$ 94
Cash paid for interest, net of interest capitalized amounts		39.7	21.4
Cash paid for income taxes		$ 27.8	$ 34.4
[1]	Capital expenditures included in current liabilities is comprised of "Accrued capital expenditures" and certain other amounts included within "Accounts payable" on the Condensed Consolidated Balance Sheet (unaudited).

Concentration of Credit Risk (N

Concentration of Credit Risk (Narrative) (Details)	6 Months Ended
	Jun. 30, 2015
Concentration Risk [Line Items]
Concentration Risk, Benchmark Description	0.1

(Schedule of Concentration Of C

(Schedule of Concentration Of Credit Risk) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Concentration Risk [Line Items]
Revenues		$ 316.1		$ 656.1
Credit Concentration Risk
Concentration Risk [Line Items]
Revenues	[1]	$ 36.2		$ 85.1
Concentration Risk, Percentage	[1]	11.50%		13.00%
Predecessor [Member]
Concentration Risk [Line Items]
Revenues			$ 343.5		$ 689.3
Predecessor [Member] | Credit Concentration Risk
Concentration Risk [Line Items]
Revenues	[1]		$ 36		$ 83.6
Concentration Risk, Percentage	[1]		10.50%		12.10%
[1]	Represents the gross amount of revenue contracted for with Columbia Gas of Ohio and, therefore, subject to risk at the loss of this customer. Columbia Gas of Ohio has entered into certain capacity release arrangements with third parties which ultimately can decrease the net revenue amount we receive from Columbia Gas of Ohio in any given period.

Subsequent Events (Narrative) (

Subsequent Events (Narrative) (Details) shares in Millions, $ in Millions	Jul. 01, 2015USD ($)shares	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)
Subsequent Event [Line Items]
Senior Notes		$ 2,722.2		$ 2,722.2
Repayments of Related Party Debt				1,087.3
Distribution to Parent				1,450
Gain on Conveyances		$ 8.3	$ 0.3	$ 13.6	$ 17.8
Subsequent Event [Member]
Subsequent Event [Line Items]
Share Distribution, Date	Jul. 1, 2015
Common Stock, Shares, Issued | shares	317.6
Distribution Payable Shareholder Date of Record	Jun. 19, 2015
Stock Trade Date	Jul. 2, 2015
Acres Conveyed	20,000
Gain on Conveyances	$ 35.8

Uncategorized Items - cpgx-2015

Label	Element	Value
Predecessor [Member]
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	$ (0.3)
Depreciation, Depletion and Amortization	us-gaap_DepreciationDepletionAndAmortization	$ 28.8