Columbia Pipeline (CPGX) 10-Q 1 Nov 16 2016 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Oct. 31, 2016
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
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	Large Accelerated Filer
Entity Units Outstanding		0

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Current Assets
Cash and cash equivalents		$ 132.6		$ 930.9	$ 63.8		$ 0.5
Accounts receivable (less reserve of $0.3 and $0.6, respectively)		159.5		152.4
Accounts receivable-affiliated		40.7		0
Materials and supplies, at average cost		26.4		32.8
Exchange gas receivable		14.3		19
Deferred property taxes		17.7		52
Prepayments and other		43.5		48.5
Total Current Assets		434.7		1,235.6
Investments
Unconsolidated affiliates		441.4		438.1
Other investments		1.8		13.8
Total Investments		443.2		451.9
Property, Plant and Equipment
Property, plant and equipment		10,200.5		9,052.3
Accumulated depreciation and amortization		(3,092.8)		(2,988.6)
Net Property, Plant and Equipment		7,107.7		6,063.7
Other Noncurrent Assets
Regulatory assets		197.7		177.7
Goodwill		1,975.5		1,975.5
Postretirement and postemployment benefits assets		111.8		115.7
Deferred charges and other		11.2		15.5
Total Other Noncurrent Assets		2,296.2		2,284.4
Total Assets		10,281.8		10,035.6
Current Liabilities
Short-term borrowings		0		15
Short-term borrowings-affiliated		250		0
Accounts payable		84.1		56.8
Accounts payable-affiliated		9.6		0
Customer deposits		16.7		17.9
Taxes accrued		67.1		106
Interest accrued		37.1		9.5
Exchange gas payable		14.2		18.6
Deferred revenue		5.6		15
Accrued capital expenditures		171.6		100.1
Accrued compensation and related costs		45.1		51.9
Other accruals		101.4		70
Total Current Liabilities		802.5		460.8
Noncurrent Liabilities
Long-term debt		2,727.7		2,725.6
Deferred income taxes		1,446.6		1,348.1
Accrued liability for postretirement and postemployment benefits		43.5		49.4
Regulatory liabilities		284.2		321.6
Asset retirement obligations		23		25.7	22.9		23.2
Other noncurrent liabilities		70.1		91.4
Total Noncurrent Liabilities		4,595.1		4,561.8
Total Liabilities		5,397.6		5,022.6
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,000 and 399,841,350 shares outstanding, respectively		0.1		4
Additional paid-in capital		4,013.8		4,032.7
(Accumulated deficit) Retained earnings		(56.7)		46.9
Accumulated other comprehensive loss	[1]	(26.3)	$ (26.2)	(27)	(25.3)	$ (24.5)	(34.5)
Total CPG Equity		3,930.9		4,056.6
Noncontrolling Interest		953.3		956.4
Total Equity		4,884.2		5,013	$ 3,549.6		$ 4,176.3
Total Liabilities and Equity		$ 10,281.8		$ 10,035.6
[1]	All amounts are net of tax. Amounts in parentheses indicate debits.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Accounts receivable less reserve	$ 0.3	$ 0.6
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	10,001,000	2,000,000,000
Common Stock, Shares, Outstanding	10,000,100	399,841,350

Statements of Consolidated Oper

Statements of Consolidated Operations - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating Revenues
Transportation revenues	$ 270.3	$ 266.2	$ 838.2	$ 752.4
Transportation revenues-affiliated	0	0	0	47.5
Storage revenues	48.9	49.5	147.7	122.3
Storage revenues-affiliated	0	0	0	26.2
Other revenues	7.9	5.2	19.6	28.6
Total Operating Revenues	327.1	320.9	1,005.5	977
Operating Expenses
Operation and maintenance	322.9	186.5	671.9	456
Operation and maintenance-affiliated	0	0	0	52.9
Depreciation and amortization	43.6	35	125.2	101.4
Gain on sale of assets	(9.3)	(39)	(15.3)	(52.6)
Impairment of long-lived assets	19.1	0.6	19.1	2.4
Property and other taxes	19.8	17.3	62.6	55.5
Total Operating Expenses	396.1	200.4	863.5	615.6
Equity Earnings in Unconsolidated Affiliates	16	15.4	48.2	44.5
Operating (Loss) Income	(53)	135.9	190.2	405.9
Other Income (Deductions)
Interest expense	(31.4)	(29.4)	(91.4)	(42.3)
Interest expense-affiliated	(0.5)	0	(0.5)	(29.3)
Other, net	13.7	6.7	30.5	16.6
Total Other Deductions, net	(18.2)	(22.7)	(61.4)	(55)
(Loss) Income from Continuing Operations before Income Taxes	(71.2)	113.2	128.8	350.9
Income Taxes	(21.6)	38.3	43.2	118.8
(Loss) Income from Continuing Operations	(49.6)	74.9	85.6	232.1
(Loss) Income from Discontinued Operations-net of taxes	0	(0.1)	0.2	(0.4)
Net (Loss) Income	(49.6)	74.8	85.8	231.7
Less: Net income attributable to noncontrolling interest	2.9	11.8	27.2	27.9
Net (loss) income attributable to CPG	(52.5)	63	58.6	203.8
Amounts Attributable to CPG
(Loss) income from continuing operations	(52.5)	63.1	58.4	204.2
(Loss) Income from Discontinued Operations-net of taxes	0	(0.1)	0.2	(0.4)
Net (loss) income attributable to CPG	$ (52.5)	$ 63	$ 58.6	$ 203.8

Statements of Consolidated Comp

Statements of Consolidated Comprehensive Income - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net (Loss) Income		$ (49.6)	$ 74.8	$ 85.8	$ 231.7
Net unrealized gain (loss) on cash flow hedges	[1]	0.3	(0.7)	1	(0.2)
Unrecognized pension and OPEB benefit (cost)	[2],[3]	(0.4)	(0.1)	(0.2)	7.2
Total other comprehensive (loss) income	[4]	(0.1)	(0.8)	0.8	7
Total comprehensive (loss) income		(49.7)	74	86.6	238.7
Less: Comprehensive Income-noncontrolling interest		2.9	11.8	27.3	27.9
Comprehensive (Loss) Income-controlling interests		$ (52.6)	$ 62.2	$ 59.3	$ 210.8
[1]	Net unrealized gain (loss) on derivatives qualifying as cash flow hedges, net of $0.3 million and $1.1 million tax expense for the three months ended September 30, 2016 and 2015, respectively, and $0.6 million and $1.4 million tax expense for the nine months ended September 30, 2016 and 2015, respectively.
[2]	Unrecognized pension and OPEB benefit (cost), net of $0.2 million and $0.1 million tax benefit for the three months ended September 30, 2016 and 2015, respectively, and $0.1 million tax benefit for the nine months ended September 30, 2016 and 2015.
[3]	Unrecognized pension and OPEB benefits are primarily related to pension and OPEB remeasurements recorded during 2016 and 2015.
[4]	All amounts are net of tax. Amounts in parentheses indicate debits.

Statements of Consolidated Com6

Statements of Consolidated Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	$ 0.3	$ 1.1	$ 0.6	$ 1.4
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax	$ (0.2)	$ (0.1)	$ (0.1)	$ (0.1)

Statements of Consolidated Cash

Statements of Consolidated Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating Activities
Net (Loss) Income	$ 85.8	$ 231.7
Adjustments to Reconcile Net Income to Net Cash from Continuing Operations:
Depreciation and amortization	125.2	101.4
Deferred income taxes and investment tax credits	81.5	77.7
Deferred revenue	(2.7)	0.4
Equity-based compensation expense and profit sharing contribution	1.6	4.4
Gain on sale of assets	(15.3)	(52.6)
Impairment of long-lived assets	19.1	2.4
Income from unconsolidated affiliates	(48.2)	(44.5)
(Income) loss from discontinued operations-net of taxes	(0.2)	0.4
Amortization of debt related costs	9.3	1.8
AFUDC equity	(29.7)	(15)
Distributions of earnings received from equity investees	51	44.1
Changes in Assets and Liabilities:
Accounts receivable	0.9	1.6
Accounts receivable-affiliated	(40.7)	34.7
Accounts payable	20.5	20.6
Accounts payable-affiliated	9.5	(53.6)
Customer deposits	(1.2)	(23.8)
Taxes accrued	(42.4)	(27.6)
Interest accrued	27.8	40.3
Exchange gas receivable/payable	0.3	0.1
Other accruals	(17.3)	37.1
Prepayments and other current assets	45.6	9.5
Regulatory assets/liabilities	(10.5)	38.2
Postretirement and postemployment benefits	(6.8)	(26)
Deferred charges and other noncurrent assets	1.3	3.8
Other noncurrent liabilities	(11.7)	7.2
Net Operating Activities from Continuing Operations	252.7	414.3
Net Operating Activities from (used for) Discontinued Operations	0.3	(0.1)
Net Cash Flows from Operating Activities	253	414.2
Investing Activities
Capital expenditures	(1,095.8)	(833)
Insurance recoveries	0	2.1
Change in short-term lendings-affiliated	0	145.5
Proceeds from disposition of assets	9.9	53.3
Contributions to equity investees	(6.2)	(1.4)
Distributions from equity investees	1.6	15.1
Other investing activities	3.8	(24.2)
Net Cash Flows used for Investing Activities	(1,086.7)	(642.6)
Financing Activities
Change in short-term borrowings	(15)	245
Change in short-term borrowings-affiliated	250	(252.5)
Issuance of long-term debt	0	2,745.9
Payments of capital lease obligations and other debt related costs	(2.5)	(23.6)
Issuance of long-term debt-affiliated	0	1,217.3
Payments of long-term debt-affiliated, including current portion	0	(2,806)
Proceeds from the issuance of common units, net of offering costs	0	1,168.4
Proceeds from Issuance of Common Stock	0.1	0
Distribution of IPO proceeds to NiSource	0	(500)
Distribution to NiSource	0	1,450
Distribution to noncontrolling interest	(30.4)	(13.9)
Acquisition of treasury stock	(6.2)	0
Dividends paid - common stock	(105.1)	(39.7)
Dividends paid to TransCanada	(55.5)	0
Transfer from parent	0	0.8
Net Cash Flows from Financing Activities	35.4	291.7
Change in cash and cash equivalents	(798.3)	63.3
Cash and cash equivalents at beginning of period	930.9	0.5
Cash and Cash Equivalents at End of Period	$ 132.6	$ 63.8

Statements of Consolidated Equi

Statements of Consolidated Equity - USD ($) $ in Millions		Total		Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Parent	Accumulated Other Comprehensive Loss	Noncontrolling Interest
Beginning Balance at Dec. 31, 2014		$ 4,176.3		$ 0		$ 0	$ 0	$ 4,210.8	$ (34.5)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		231.7		0		0	63	140.8	0
Net income attributable to noncontrolling interest		27.9
Other comprehensive income, net of tax		7	[1]	0		0	0	0	7	0
Allocation of AOCI to noncontrolling interest		0		0		0	0	0	2.2	(2.2)
Issuance of common units of CPPL		1,168.4		0		0	0	0	0	1,168.4
Distribution of IPO proceeds to NiSource		(500)		0		0	0	(500)	0	0
Distribution to NiSource		1,450		0		0	0	1,450	0	0
Purchase of additional interest in Columbia OpCo	[2]	0		0		0	0	227.1	0	(227.1)
Common stock dividends		(79.5)		0		0	(79.5)	0	0	0
Net transfers from NiSource		6.3		0		0	0	6.3	0	0
Reclassification of net parent investment to additional paid-in capital		0		0		2,635	0	(2,635)	0	0
Issuance of common stock		0		3.2		(3.2)	0	0	0	0
Net transfers from NiSource		1.4		0		1.2	0	0	0	0.2
Long-term incentive plan		1.9		0		1.9	0	0	0	0
Distributions to noncontrolling interest		(13.9)		0		0	0	0	0	(13.9)
Ending Balance at Sep. 30, 2015		3,549.6		3.2		2,634.9	(16.5)	$ 0	(25.3)	953.3
Beginning Balance at Dec. 31, 2015		5,013		4	$ 0	4,032.7	46.9		(27)	956.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		85.8		0	0	0	58.6		0
Net income attributable to noncontrolling interest		27.2
Other comprehensive income, net of tax		0.8	[1]	0	0	0	0		0.7	0.1
Distribution of IPO proceeds to NiSource		0
Distribution to NiSource		0
Common stock dividends		(105.1)		0	0	0	(105.1)		0	0
Dividend to TransCanada		(55.5)		0	0	0	(55.5)		0	0
Common stock purchased by TransCanada and retired		(10,216.7)		(4)	0	(10,212.7)	0		0	0
Issuance of common stock		10,216.8		0.1	0	10,216.7	0		0	0
Treasury stock acquired		(6.2)		0	(6.2)	0	0		0	0
Treasury stock retirement		0		0	6.2	(4.6)	(1.6)		0	0
Distributions to noncontrolling interest		(30.4)		0	0	0	0		0	(30.4)
Long-term incentive plan		(18.3)		0	0	(18.3)	0		0	0
Ending Balance at Sep. 30, 2016		$ 4,884.2		$ 0.1	$ 0	$ 4,013.8	$ (56.7)		$ (26.3)	$ 953.3
[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 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) $ in Millions	9 Months Ended
	Sep. 30, 2015USD ($)
Issuance of common units of CPPL	$ 1,168.4
Noncontrolling Interest
Issuance of common units of CPPL	$ 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	9 Months Ended
	Sep. 30, 2016
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 on September 26, 2014 to own, operate and develop a portfolio of pipelines, storage and related midstream assets. 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 subordinated units and incentive distribution rights. CPG did not have any material assets or liabilities as a separate corporate entity until the contribution of CEG from NiSource on February 11, 2015. CPG is engaged in regulated gas transportation and storage services for LDCs, 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 such as 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. Separation. On June 2, 2015, NiSource announced that its board of directors 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, NiSource distributed, pursuant to an effective registration statement on Form 10, 317.6 million shares, one share of CPG common stock for every one share of NiSource common stock held by NiSource stockholders on the Record Date. As of July 1, 2015, CPG was an independent, publicly traded company, and NiSource did not retain any ownership interest in CPG. CPG's common stock began trading "regular-way" under the ticker symbol "CPGX" on the NYSE on July 2, 2015. In connection with the Separation, CPG completed the following transactions: • In May 2015, CPG completed its private placement of senior notes and received proceeds of approximately $2,722.3 million . CPG utilized a portion of the proceeds to repay approximately $1,087.3 million of intercompany debt and short-term borrowings, including, net amounts due from the money pool between CPG and NiSource Finance Corp. ("NiSource Finance"); • CPG further utilized the proceeds from the senior notes to make a cash distribution of approximately $1,450.0 million to NiSource; and • Accounts related to NiSource and its subsidiaries, including accounts receivable and accounts payable, were reclassified from affiliated to non-affiliated. Agreements with NiSource following the Separation . CPG entered into the Separation and Distribution Agreement and several other agreements with NiSource to effect the Separation and provide a framework for CPG's relationship with NiSource, and its subsidiaries, after the Separation. The Separation and Distribution Agreement contains many of the key provisions related to CPG's separation from NiSource and the distribution of CPG's shares of common stock to NiSource's stockholders, including cross-indemnities between CPG and NiSource. In general, NiSource has agreed to indemnify CPG for any liabilities relating to NiSource's business and CPG has agreed to indemnify NiSource for any liabilities relating to CPG's business. In addition to the Separation and Distribution Agreement, CPG entered into the following agreements with NiSource related to the Separation: • Tax Allocation Agreement - Provides for the respective rights, responsibilities, and obligations of NiSource and CPG with respect to tax liabilities and benefits, tax attributes, the preparation and filing of tax returns, tax contests, and certain other matters regarding taxes. • Employee Matters Agreement - Provides for the respective obligations to employees and former employees who are or were associated with CPG (including those employees who transferred employment from NiSource to CPG prior to the Separation) and for other employment and employee benefits matters. • Transition Services Agreement - Provides for the provision of certain transitional services by NiSource to CPG, and vice versa. The services may include the provision of administrative and other services identified by the parties. The charge for these services is expected to be based on actual costs incurred by the party rendering the services without profit. Merger. On March 17, 2016 , CPG entered into an Agreement and Plan of Merger (the "Merger Agreement"), among CPG, TCPL, US Parent, Taurus Merger Sub Inc., a Delaware corporation and a wholly owned subsidiary of US Parent ("Merger Sub"), and, solely for purposes of Section 3.02, Section 5.02, Section 5.09 and Article VIII of the Merger Agreement, TransCanada. Upon the terms and subject to the conditions set forth in the Merger Agreement, effective July 1, 2016, Merger Sub was merged with and into CPG (the "Merger") with CPG surviving the Merger as an indirect wholly owned subsidiary of TransCanada. On July 1, 2016 , TransCanada closed the acquisition of CPG valued at $13.0 billion , comprised of a purchase price of approximately $10.3 billion and CPG debt of approximately $2.7 billion . CPG became an indirect, wholly owned subsidiary of TransCanada as a result of the Merger. Subject to the terms and conditions of the Merger Agreement, at the effective time of the Merger, each issued and outstanding share of CPG common stock, par value $0.01 per share, was canceled and converted into the right to receive $25.50 per share in cash, without interest. Upon completion of the transaction, TransCanada owns the general partner of CPPL, all of CPPL’s incentive distribution rights and all of CPPL's subordinated units, which represent a 46.5% limited partnership interest in CPPL. As a result, CPPL is now effectively managed by TransCanada. For the three and nine months ended September 30, 2016 , CPG incurred Merger transaction costs of $43.1 million and $66.3 million , respectively, including legal, advisory and other related fees. These costs are included in "Operation and maintenance" on the Condensed Statements of Consolidated Operations (unaudited). Approximately $101.5 million of employee related costs were incurred subsequent to the Merger. Additionally as a result of the Merger, CPG recognized an impairment charge of $19.1 million related to the cancellation of IT system upgrades that were in process prior to the Merger. CPG has suspended its obligation to file periodic reports with the SEC based on its common stock as a result of the Merger. CPG will continue to have reporting obligations with respect to its senior notes. Refer to Note 6, "Long-Term Debt" for additional information on CPG's senior notes. The Condensed Consolidated Financial Statements (unaudited) have been prepared pursuant to the rules and regulations of the SEC. 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 financial statements for the year ended December 31, 2015 (the "2015 Form 10-K"). 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 Operations (unaudited) are not necessarily indicative of amounts expected for the respective annual periods. CPG's accompanying Condensed Consolidated Financial Statements (unaudited) have been prepared in accordance with GAAP. 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 and Columbia OpCo. All intercompany transactions and balances have been eliminated. Also included in the Condensed Consolidated Financial Statements (unaudited) are equity method investments Hardy Storage, Millennium Pipeline and Pennant.

CPPL Initial Public Offering

CPPL Initial Public Offering	9 Months Ended
	Sep. 30, 2016
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 the IPO. CPG owns the general partner of CPPL and all of CPPL's subordinated units and 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 are consolidated in CPG's results. As of September 30, 2016 , the portion of CPPL owned by the public is reflected as a noncontrolling interest in the Condensed Consolidated Financial Statements (unaudited). The table below summarizes the effects of changes in CPG’s ownership interest in Columbia OpCo on equity: Three Months Ended Nine Months Ended (in millions) 2016 2015 2016 2015 Net (loss) income attributable to CPG $ (52.5 ) $ 63.0 $ 58.6 $ 203.8 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 $ (52.5 ) $ 63.0 $ 58.6 $ 430.9

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments . ASU 2016-15 amends the guidance in ASC 230 on the classification of certain cash receipts and payments in the statement of cash flows. CPG is required to adopt ASU 2016-15 for periods beginning after December 15, 2017, 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 2016-15 will have on the Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited). 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 August 2015, the FASB issued ASU 2015-14 to extend 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 permitted on the original effective date of ASU 2014-09 on a limited basis. In March 2016, the FASB issued ASU 2016-08, which amends the principal-versus-agent implementation guidance and illustrations in ASU 2014-09. Among other things, ASU 2016-08 clarifies that an entity should evaluate whether it is the principal or the agent for each specified good or service promised in a contract with a customer. In April 2016, the FASB issued ASU 2016-10, which clarifies guidance related to identifying performance obligations and licensing implementation guidance contained in ASU 2014-09. In May 2016, the FASB issued ASU 2016-12, which contains narrow scope improvements for certain aspects of ASU 2014-09 including collectability, presentation of sales tax and other similar taxes collected from customers, noncash consideration, contract modifications and completed contracts at transition and transition technical correction. CPG is currently evaluating the impact the adoption of ASU 2014-09, and the related ASUs, will have on the Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited). In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718) . ASU 2016-09 simplifies several aspects of the accounting for employee share-based payment transactions, including the accounting for income taxes, forfeitures and statutory tax withholding requirements, as well as classification in the statement of cash flows. CPG is required to adopt ASU 2016-09 for periods beginning after December 15, 2016, including interim periods, with early adoption permitted. CPG is currently evaluating the impact the adoption of ASU 2016-09 will have on the Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited). In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) . ASU 2016-02 introduces a lessee model that brings most leases on the balance sheet. The new standard also aligns many of the underlying principles of the new lessor model with those in ASC 606, the FASB's new revenue recognition standard (e.g., those related to evaluating when profit can be recognized). Furthermore, ASU 2016-02 addresses other concerns related to the current leases model. For example, ASU 2016-02 eliminates the requirement in current U.S. GAAP for an entity to use bright-line tests in determining lease classification. The standard also requires lessors to increase the transparency of their exposure to changes in value of their residual assets and how they manage that exposure. CPG is required to adopt ASU 2016-02 for periods beginning after December 15, 2018, including interim periods, with early adoption permitted. CPG is currently evaluating the impact the adoption of ASU 2016-02 will have on the Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated 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. In August 2015, the FASB issued ASU 2015-15 to clarify the SEC staff's position on these costs in relation to line-of-credit agreements stating that the SEC staff would not object to an entity deferring and presenting debt issuance costs related to a line-of-credit arrangement as an asset and subsequently amortizing the deferred debt issuance costs ratably over the term of such arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit. CPG adopted ASU 2015-03 and ASU 2015-15 as of January 1, 2016, resulting in the reclassification of unamortized balance of debt issuance costs from "Deferred charges and other" to "Long-term debt." This change in accounting principle was applied retrospectively. As of December 31, 2015, the balance of unamortized debt issuance costs recorded in "Deferred charges and other" was $20.6 million . As a result of the retrospective adjustment, the December 31, 2015 balances of "Deferred charges and other" and "Long-term debt" were reduced by $20.6 million on the Condensed Consolidated Balance Sheets (unaudited) and Notes to Condensed Consolidated 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 retrospectively adopted ASU 2015-02 as of January 1, 2016. The adoption of this guidance did not have a material impact on the Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited).

Transactions with Affiliates

Transactions with Affiliates	9 Months Ended
	Sep. 30, 2016
Related Party Transactions [Abstract]
Transactions with Affiliates	Transactions with Affiliates Transactions with TransCanada Subsequent to the completion of the Merger, CPG engaged in transactions with subsidiaries of TransCanada, which are deemed to be affiliates of CPG. Transactions with affiliates subsequent to the Merger are summarized below: Interest Expense. CPG was charged interest for short-term borrowings of $0.5 million for the three and nine months ended September 30, 2016. Accounts Receivable . The affiliated accounts receivable balance of $40.7 million due from TransCanada represents amounts allocated to CPG pursuant to TransCanada's tax allocation agreement. Accounts Payable . The affiliated accounts payable balance of $9.6 million primarily includes amounts due for insurance coverage and interest payable to TransCanada. CPG-TransCanada PipeLine USA Ltd. Revolving Credit Facility. Subsequent to the completion of the Merger, CPG entered into a $2,000.0 million revolving credit facility with US Parent. The revolving credit facility became effective as of July 1, 2016, with no termination date. The revolving credit facility is available for general corporate purposes, including capital expenditures. Loans under the revolving credit facility 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 as defined by Bloomberg Professional Service or (c) the Eurodollar rate which is based on the one month LIBOR, plus 1.000 percent , each of which is subject to a margin of 0.250 percent per annum, or (ii) the Eurodollar rate plus a margin of 1.250 percent per annum. As of September 30, 2016 , CPG had $250.0 million in outstanding borrowings under the revolving credit facility, with a weighted average interest rate of 1.87% . Given their maturity and turnover is three months or less, cash flows related to the borrowings and repayments of the revolving credit facilities are presented net in the Condensed Statements of Consolidated Cash Flows (unaudited). Dividends to TransCanada . During the three months ended September 30, 2016, CPG distributed $55.5 million to TransCanada for the dividend of $0.13875 per share declared on May 10, 2016 . Transactions with NiSource Prior to the Separation, CPG engaged in transactions with subsidiaries of NiSource, which at that time were deemed to be affiliates of CPG. The Separation occurred on July 1, 2015 and for periods after this date CPG and the subsidiaries of NiSource are no longer affiliates. Transactions with affiliates prior to the Separation are summarized below: Transportation, Storage and Other Revenues . CPG provided natural gas transportation, storage and other services to subsidiaries of NiSource, former affiliates. For the nine months ended September 30, 2015 , CPG recognized transportation revenues of $47.5 million , storage revenues of $26.2 million and other revenues of $0.2 million . Operation and Maintenance Expense . CPG received executive, financial, legal, information technology and other administrative and general services from a former affiliate, NiSource Corporate Services. Expenses incurred as a result of these services consisted of employee compensation and benefits, outside services and other expenses. CPG was 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. For the nine months ended September 30, 2015 , operation and maintenance expense was $52.9 million . Interest Expense and Income . Prior to the private placement of senior notes on May 22, 2015, CPG paid NiSource interest for intercompany long-term debt outstanding. For the nine months ended September 30, 2015 , CPG was charged interest for long-term debt of $31.0 million , offset by associated AFUDC of $2.4 million . 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. Following the Separation, the agreement is with CPG. 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. Prior to the Separation, NiSource Corporate Services administered the money pools. Prior to the Separation, the cash accounts maintained by the subsidiaries of Columbia OpCo and CPG were 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 was determined by the net position of each subsidiary in the money pool. Subsequent to the Separation, the intercompany money pool balances and related interest expense and income are eliminated as intercompany activity. The money pool weighted-average interest rate at September 30, 2015 was 1.21% . For the nine months ended September 30, 2015 , the interest expense for short-term borrowings charged was $0.7 million . For the nine months ended September 30, 2015 , interest income for short-term borrowings was $2.5 million . Dividends to NiSource . During the nine months ended September 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. There were no restrictions on the payment by CPG of dividends to NiSource.

Short-Term Borrowings

Short-Term Borrowings	9 Months Ended
	Sep. 30, 2016
Short-term Debt [Abstract]
Short-Term Borrowings	Short-Term Borrowings CPG Revolving Credit Facility. As of December 31, 2015 , CPG had no outstanding borrowings and had $18.1 million in letters of credit under the revolving credit facility. On July 1, 2016, in connection with the Merger, all existing letters of credit were migrated to a TransCanada credit facility and the CPG revolving credit facility was terminated. As a result, CPG accelerated the amortization of $4.3 million of deferred costs associated with the revolving credit facility, which are included in interest expense for the three and nine months ended September 30, 2016 . CPPL Revolving Credit Facility. As of December 31, 2015 , CPPL had $15.0 million in outstanding borrowings, with a weighted average interest rate of 1.28% , and issued no letters of credit under the revolving credit facility. On June 29, 2016, in anticipation of the Merger, all outstanding borrowings, facility fees and interest were paid in full and the revolving credit facility was terminated. As a result, CPPL accelerated the amortization of $1.4 million of deferred costs associated with the revolving credit facility, which are included in interest expense for the nine months ended September 30, 2016 . CPG Commercial Paper Program. CPG's commercial paper program (the "Program") had a Program limit of up to $1,000.0 million . CEG, OpCo GP and Columbia OpCo each agreed, jointly and severally, unconditionally and irrevocably to guarantee payment in full of the principal of and interest (if any) on the promissory notes. As of December 31, 2015 , CPG had no promissory notes outstanding under the Program. On June 30, 2016, in anticipation of the Merger, the Program was terminated. CPG had no promissory notes outstanding under the Program at the time of termination. Given their maturity and turnover is three months or less, cash flows related to the borrowings and repayments of the CPG and CPPL revolving credit facilities and the Program are presented net in the Condensed Statements of Consolidated Cash Flows (unaudited).

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2016
Debt Instrument [Line Items]
Long-Term Debt	Long-Term Debt Senior notes issuance. On May 22, 2015 , CPG issued a private placement of $2,750.0 million in aggregate principal amount of 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 initial guarantors are three subsidiaries of CPG, CEG, Columbia OpCo and OpCo GP (the "Guarantors"). 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 guarantees of any Guarantor may be released under certain circumstances. The Notes and the guarantees are (a) unsecured, (b) effectively junior in right of payment to any future secured indebtedness of CPG and the Guarantors, (c) equal in right of payment with any existing and future unsubordinated indebtedness of CPG and the Guarantors and (d) senior in right of payment to any future subordinated indebtedness of CPG and the Guarantors. 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. On February 23, 2016, CPG filed an exchange offer registration statement with the SEC. The registration statement was declared effective as of April 14, 2016.

Gain on Sale of Assets

Gain on Sale of Assets	9 Months Ended
	Sep. 30, 2016
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 September 30, 2016 and 2015 , gains on conveyances amounted to $9.7 million and $36.0 million , respectively, and are included in "Gain on sale of assets" on the Condensed Statements of Consolidated Operations (unaudited). For the nine months ended September 30, 2016 and 2015 , gains on conveyances amounted to $15.7 million and $49.6 million , respectively, and are included in "Gain on sale of assets" on the Condensed Statements of Consolidated Operations (unaudited). Included in the gains on conveyances is a cash bonus payment of $9.0 million and $35.8 million received by CEVCO from CNX Gas Company LLC during the three and nine months ended September 30, 2016 and 2015 , respectively, for the lease of Utica Shale and Upper Devonian gas rights in Greene and Washington Counties in Pennsylvania and Marshall and Ohio Counties in West Virginia. As of September 30, 2016 and December 31, 2015 , deferred gains of approximately $1.3 million and $8.1 million , respectively, were deferred pending performance of future obligations and recorded within "Deferred revenue," on the Condensed Consolidated Balance Sheets (unaudited).

Goodwill

Goodwill	9 Months Ended
	Sep. 30, 2016
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 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 CPG's goodwill relates to NiSource's acquisition of CEG in 2000, which was contributed to CPG prior to the Separation. CPG’s goodwill assets at September 30, 2016 were $1,975.5 million . CPG's predecessor 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, 2016 . 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 recent Merger Agreement and acquisition price were incorporated into the current year testing. 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. In consideration of all relevant factors, there were no indicators that would require a subsequent goodwill impairment test during the third quarter of 2016 .

Asset Retirement Obligations

Asset Retirement Obligations	9 Months Ended
	Sep. 30, 2016
Asset Retirement Obligation [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations Changes in CPG's liability for asset retirement obligations for the nine months ended September 30, 2016 and 2015 are presented in the table below: (in millions) 2016 2015 Balance as of January 1, $ 25.7 $ 23.2 Accretion expense 0.8 0.9 Additions — 0.4 Settlements — — Change in estimated cash flows (3.5 ) (1.6 ) Balance as of September 30, $ 23.0 $ 22.9 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 certain assets, which include gas pipelines and natural gas storage wells, will operate for an indeterminate future period when properly maintained. A liability for these asset retirement obligations will be recorded only if and when a future retirement obligation with a determinable life is identified.

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2016
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Matters	Regulatory Matters Columbia Gas Transmission Modernization Program. In November 2015, Columbia Gas Transmission commenced the fourth year of the Columbia Gas Transmission long-term system modernization program. Columbia Gas Transmission expects to place approximately $300 million in modernization investments into service during the year. Recovery of the revenue requirement on approximately $320 million of investments made in 2015 began on February 1, 2016. In December 2015, Columbia Gas Transmission filed an extension of this settlement and received the FERC's approval of the customer agreement in March 2016. This extension will allow Columbia Gas Transmission to invest an additional $1.1 billion over an additional three-year period through 2020. This agreement also expands the scope of facility investments covered by the program. Columbia Gulf. On January 21, 2016, the FERC issued an Order (the "January 21 Order") initiating an investigation pursuant to Section 5 of the NGA to determine whether Columbia Gulf's existing rates for jurisdictional services are unjust and unreasonable. Columbia Gulf filed a cost and revenue study with the FERC on April 5, 2016, as required by the January 21 Order. The January 21 Order directed that a hearing be conducted pursuant to an accelerated timeline and that an initial decision be issued by February 28, 2017. On June 13, 2016, the FERC trial staff, Columbia Gulf, and all of the active parties filed a Joint Motion to Suspend the Procedural Schedule and Waive Answer Period (the "Motion"). The Motion represents that the parties unanimously support the Motion and requested waiver of the answer period, which was granted. The parties reached an agreement in principle during a June 2, 2016 settlement conference that would fully resolve all matters set for hearing by the FERC. The Motion represents that the parties expect to file an offer of settlement memorializing the agreement in principle no later than July 29, 2016, and suspension of the procedural schedule will promote an efficient and speedy resolution of this matter by allowing the participants to focus their efforts on drafting the necessary settlement documents. Columbia Gulf filed the offer of settlement with the FERC in accordance with the agreement noted above. On August 15, 2016, the administrative law judge issued a Certification of Uncontested Settlement, which noted that no parties objected to the provisions in the offer of settlement. On September 22, 2016, the FERC issued an order approving the uncontested settlement, which requires a reduction in Columbia Gulf’s daily maximum recourse rate and addresses Columbia Gulf’s treatment of postretirement benefits other than pensions, pension expenses, and regulatory expenses. The order also requires Columbia Gulf to file a general rate case under section 4 of the NGA by January 31, 2020, for rates to take effect by August 1, 2020. Other terms of the settlement are included in FERC Docket No. RP16-302-000. 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 NGA. 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	9 Months Ended
	Sep. 30, 2016
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	Equity Method Investments Certain investments of CPG are accounted for under the equity method of accounting. These investments are recorded within "Unconsolidated affiliates" on the Condensed Consolidated Balance Sheets (unaudited) and CPG's portion of the results is reflected in "Equity Earnings in Unconsolidated Affiliates" on the Condensed Statements of Consolidated 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. The following table contains contribution and distribution data representing CPG's portion based on CPG's ownership percentage of each investment: Three Months Ended Nine Months Ended (in millions) 2016 2015 2016 2015 Millennium Pipeline Contributions to Millennium Pipeline $ 4.3 $ 1.4 $ 6.2 $ 1.4 Distributions of earnings from Millennium Pipeline 17.5 13.3 41.3 37.5 Hardy Storage Contributions to Hardy Storage — — — — Distributions of earnings from Hardy Storage — — 1.4 1.0 Pennant Contributions to Pennant — — — — Distributions of earnings from Pennant 2.3 2.9 8.3 5.6 Return of capital from Pennant 0.8 0.2 1.6 2.4 During the third quarter of 2015, an additional member joined the Pennant joint venture. The member's initial ownership investment in Pennant is 5.00% , and by funding specified, disproportionate investment amounts for future growth projects, the member can invest directly in the growth of Pennant. Such funding will potentially increase the member's ownership in Pennant up to 33.33% over a defined investment period. As a result of the buy-in, Columbia Midstream received $12.7 million in cash and recorded a gain of $2.9 million , and its ownership interest in Pennant decreased from 50.00% to 47.50% .

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes CPG's interim effective tax rates reflect the estimated annual effective tax rates for 2016 and 2015 , adjusted for tax expense associated with certain discrete items. The effective tax rates for the three months ended September 30, 2016 and 2015 were 30.3% and 33.8% , respectively. The annual effective tax rate was adjusted in the third quarter of 2016 to reflect the impact of the Merger. Refer to Note 1, "Basis of Accounting Presentation" for additional information on the Merger. The effective tax rates for the nine months ended September 30, 2016 and 2015 were 33.5% and 33.9% , respectively. The effective tax rates for 2016 and 2015 differ 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. Subsequent to the Merger, CPG is party to a Federal tax allocation agreement with US Parent and as a result will be included in the consolidated Federal income tax return filed by US Parent. The tax allocation arrangement allocates to CPG an amount of Federal income tax liabilities and benefits similar to that which would be if CPG had filed a separate return. For states that require consolidated or combined returns, CPG will be included with certain TransCanada affiliates and will settle its state income tax liabilities and benefits with US Parent.

Pension and Other Postretiremen

Pension and Other Postretirement Benefits	9 Months Ended
	Sep. 30, 2016
Pension and Other Postretirement Benefit Expense [Abstract]
Pension and Other Postretirement Benefits	Pension and Other Postretirement Benefits CPG provides defined contribution plans and noncontributory defined benefit retirement plans that cover its employees. Benefits under the defined benefit retirement plans reflect the employees' compensation, years of service and age at retirement. Additionally, CPG provides health care and life insurance benefits for certain retired employees. 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 trusts, including a grantor trust used to fund benefits of the CPG non-qualified defined benefit plan. Prior to the Separation, CPG was a participant in the consolidated NiSource defined benefit retirement plans and was allocated a ratable portion of NiSource's trusts for the plans in which its employees and retirees participated. As a result, CPG followed multiple employer accounting under the provisions of GAAP. CPG continues to follow multiple employer accounting following the Separation. For the nine months ended September 30, 2016 , CPG has made no contributions to its pension plans and contributed $1.6 million to its other postretirement benefit plans. The following table provides the components of CPG's net periodic benefits cost for the three and nine months ended September 30, 2016 and 2015 : Pension Benefits Other Postretirement Three Months Ended September 30, (in millions) 2016 2015 2016 2015 Components of Net Periodic Benefit Cost (Income) Service cost $ 1.6 $ 1.6 $ 0.2 $ 0.2 Interest cost 3.7 4.0 1.1 1.2 Expected return on assets (5.9 ) (7.0 ) (3.5 ) (4.6 ) Amortization of prior service credit (0.3 ) (0.3 ) (0.2 ) (0.2 ) Recognized actuarial loss (gain) 3.0 2.6 0.1 (0.1 ) Net Periodic Benefit Cost (Income) 2.1 0.9 (2.3 ) (3.5 ) Additional loss recognized due to: Settlement loss 2.6 — — — Total Net Periodic Benefit Cost (Income) $ 4.7 $ 0.9 $ (2.3 ) $ (3.5 ) Pension Benefits Other Postretirement Nine Months Ended September 30, (in millions) 2016 2015 2016 2015 Components of Net Periodic Benefit Cost (Income) Service cost $ 4.8 $ 4.3 $ 0.7 $ 0.8 Interest cost 11.5 11.0 3.4 3.5 Expected return on assets (19.2 ) (21.0 ) (11.6 ) (13.8 ) Amortization of prior service credit (0.9 ) (0.9 ) (0.5 ) (0.5 ) Recognized actuarial loss (gain) 9.2 7.3 0.2 (0.1 ) Net Periodic Benefit Cost (Income) 5.4 0.7 (7.8 ) (10.1 ) Additional loss recognized due to: Settlement loss 2.6 — — — Total Net Periodic Benefit Cost (Income) $ 8.0 $ 0.7 $ (7.8 ) $ (10.1 ) As of July 1, 2016, the CPG pension and other postretirement benefit plans were remeasured as a result of the acquisition by TransCanada. The remeasurement resulted in a decrease to the pension benefit obligation, net of plan assets, of $4.9 million , and a decrease to regulatory assets and accumulated other comprehensive loss of $1.2 million and $0.3 million , respectively. Net periodic pension cost for the remainder of 2016 increased by $0.9 million as a result of the remeasurement. A settlement charge of $2.6 million was recorded as a result of the non-qualified pension plan being terminated in connection with the Merger. The other postretirement benefits obligation, net of plan assets, decreased by $11.2 million as a result of the remeasurement. Additionally, the remeasurement resulted in an increase to regulatory assets of $8.6 million , a decrease to regulatory liabilities of $1.8 million and a decrease to accumulated other comprehensive loss of $0.5 million . Net periodic other postretirement benefit cost for the remainder of 2016 increased by $1.1 million as a result of the remeasurement. The following table provides the key assumptions that were used to calculate the pension and other postretirement benefit obligation and the net periodic benefit cost at the measurement dates of July 1, 2016 and December 31, 2015. Pension Benefits Other Postretirement July 1, 2016 December 31, 2015 July 1, 2016 December 31, 2015 Actuarial Assumptions Discount Rate 3.75 % 4.05 % 3.95 % 4.29 % Expected return on assets 6.75 % 8.20 % 6.36 % 8.05 % Health Care Trend Rates Trend for 2016 8.81 % 8.39 % Ultimate Trend 4.50 % 4.50 % Year Ultimate Trend Reached 2023 2022

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2016
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 and short-term borrowings. CPG's long-term debt is 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. The fair value of these securities is 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 nine months ended September 30, 2016 and for the year ended December 31, 2015 , 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 September 30, 2016 (1) Estimated Fair Value as of September 30, 2016 Carrying Amount as of December 31, 2015 (1) Estimated Fair Value as of December 31, 2015 Long-term debt $ 2,750.0 $ 2,987.8 $ 2,750.0 $ 2,592.1 (1) The carrying amount of the Notes differs from the Long-term debt balance on the Condensed Consolidated Balance Sheets (unaudited) due to the related unamortized discount and unamortized debt issuance costs, both of which are being amortized over the weighted average life of the Notes.

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2016
Share-based Compensation [Abstract]
Share-Based Compensation	Share-Based Compensation Merger. On July 1, 2016, at the effective time of the Merger, each outstanding restricted stock unit, performance share and phantom unit, whether or not vested, was deemed to be fully vested (in the case of performance shares, based on performance deemed satisfied at the greater of actual performance for the relevant period and the target level of 100%), canceled and converted into the right of the holder to receive $25.50 in cash, without interest, in respect of each share of CPG common stock underlying such award. CPG recognized stock-based employee compensation expense of $56.3 million and $0.1 million for the three months ended September 30, 2016 and 2015 , respectively, as well as related tax benefits of $18.8 million and zero , respectively. For the nine months ended September 30, 2016 and 2015 , CPG recognized stock-based employee compensation expense of $63.9 million and $3.2 million , respectively, as well as related tax benefits of $21.5 million and $1.2 million , respectively. Restricted Stock Units and Restricted Stock . During the nine months ended September 30, 2016 , CPG granted 12,144 restricted stock units and shares of restricted stock, subject to service conditions. The total grant date fair-value of the shares of restricted stock units and shares of restricted stock was $0.2 million . There are no restricted stock units or shares of restricted stock outstanding following the effective time of the Merger. Performance Shares . During the nine months ended September 30, 2016 , CPG granted 955,848 performance shares, subject to performance and service conditions. The grant date fair-value of the awards was $17.0 million . There are no performance shares outstanding following the effective time of the Merger. Non-employee Director Awards . Restricted stock units were granted annually to non-employee directors, subject to a non-employee director's election to defer receipt of such restricted stock unit award. The non-employee director's restricted stock units would vest on the first anniversary of the grant thereof subject to special pro-rata vesting rules in the event of Retirement or Disability (as defined in the award agreement), or death. The vested restricted stock units were payable as soon as practicable following vesting except as otherwise provided pursuant to the non-employee director's election to defer. There are no units outstanding to non-employee directors following the effective time of the Merger. Fully vested restricted stock units that remained outstanding under the NiSource Plan and NiSource Director Plan as of the Separation date were converted into CPG awards. All such awards were distributed to the directors upon their separation from CPG's board of directors. There are no restricted stock units outstanding following the effective time of the Merger. 401(k) Match, Profit Sharing and Company Contribution. CPG has a voluntary 401(k) savings plan covering eligible employees that allows for periodic discretionary matches as a percentage of each participant's contributions. CPG also has a retirement savings plan that provides for discretionary profit sharing contributions to eligible employees based on earnings results; and eligible exempt employees hired after January 1, 2013, receive a non-elective company contribution of three percent of eligible pay. For the three months ended September 30, 2016 and 2015 , CPG recognized 401(k) match, profit sharing and non-elective contribution expense of $3.0 million and $2.2 million , respectively. For the nine months ended September 30, 2016 and 2015 , CPG recognized 401(k) match, profit sharing and non-elective contribution expense of $9.2 million and $6.6 million , respectively.

Other Commitments and Contingen

Other Commitments and Contingencies	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [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 September 30, 2016 and the years in which they expire were: (in millions) Total 2016 2017 2018 2019 2020 After Other guarantees $ 45.3 $ — $ 2.4 $ — $ — $ — $ 42.9 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. CPG maintained a $1,500.0 million senior revolving credit facility, of which $250.0 million in letters of credit was available. On July 1, 2016, in connection with the Merger, all existing letters of credit were migrated to a TransCanada credit facility and the CPG revolving credit facility was terminated. CPPL maintained a $500.0 million senior revolving credit facility, of which $50.0 million was available for issuance of letters of credit. On June 29, 2016, in anticipation of the Merger, all outstanding borrowings, facility fees and interest were paid in full and the revolving credit facility was terminated. CPG's commercial paper program had a Program limit of up to $1,000.0 million . CEG, OpCo GP and Columbia OpCo each agreed, jointly and severally, unconditionally and irrevocably to guarantee payment in full of the principal of and interest (if any) on the promissory notes. On June 30, 2016, in anticipation of the Merger, the Program was terminated. CPG had no promissory notes outstanding under the Program at the time of termination. Other Guarantees or Obligations. CPG has purchase and sale agreement guarantees totaling $45.3 million , which guarantee purchaser performance or seller performance under covenants, obligations, liabilities, representations or warranties under the agreements. No amounts related to the purchase and sale agreement guarantees are reflected in the Condensed Consolidated Balance Sheets (unaudited). Management believes that the likelihood CPG would be required to perform or otherwise incur any significant losses associated with any of the aforementioned guarantees is remote. 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 financial statements. Please see Item 1 of Part II, Legal Proceedings, for more information. Litigation Relating to the Merger. On March 30, 2016, two purported stockholders of CPG filed an action challenging the Merger on behalf of a putative class of CPG stockholders in the Court of Chancery of the State of Delaware, captioned Vann v. Columbia Pipeline Group, Inc. , et al . The action names as defendants CPG, the members of the Board, Parent, US Parent, Merger Sub and TransCanada. On April 7, 2016, a second, substantially identical action was filed in the same court on behalf of the same putative class, captioned Baldino v. Skaggs, Jr., et al. , and naming as defendants only the members of the Board. On May 25, 2016, the Delaware Court of Chancery entered an order that, among other things, consolidated the actions into a single action, captioned as In re Columbia Pipeline Group, Inc. Stockholder Litigation , and appointed the Vann plaintiffs as lead plaintiffs and the Vann plaintiffs’ counsel as lead counsel. The Vann plaintiffs’ amended complaint, filed May 12, 2016, alleges that members of the CPG Board breached their fiduciary duties by, among other things, agreeing to the Merger following an inadequate sale process and at an unfair price, and because the sale process purportedly was affected by conflicts of interest on the part of the Board, the management of CPG and/or CPG’s largest stockholder as a result of their substantial stockholdings in CPG, and on the part of one of CPG’s financial advisors as a result of its alleged holdings in TransCanada stock. The amended complaint also alleges that the preliminary proxy filed in respect of the Merger omits or misstates various facts concerning, among other things, the sale process and the financial analyses performed by CPG’s financial advisors. The amended complaint purports to seek injunctive and other equitable relief regarding the Merger. On July 5, 2016, the defendants filed a motion to dismiss the action and a motion to stay discovery pending resolution of the motion to dismiss. Both motions remain pending. On July 18, 2016, Vice Chancellor Laster entered the briefing schedule deferring briefing on the motion to dismiss until the motion to stay is resolved. On September 6, 2016, Vice Chancellor Laster granted TransCanada and CPG’s motion to stay discovery while the motion to dismiss was pending. On October 6, 2016, the Vann plaintiffs filed an amended claim which removed all TransCanada parties, limiting the action to the CPG Board and CFO. Its revised claim alleges that the Board and officers entered into a secret scheme to benefit directors and insiders via change in control benefits and payments originating when NiSource first spun off the Columbia assets. They continue their allegations that conflict of interest tainted the acquisition, the acquisition undervalued CPG and that the proxy statement was materially deficient. The new claim seeks rescissory damages in an amount to be proven at trial and disgorgement of profits from the sale. At this early stage of the litigation, no outcome or possible loss or range of losses, if any, arising from the litigation is able to be estimated. 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 material 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 September 30, 2016 and December 31, 2015 , CPG had liabilities recorded of approximately $8.0 million and $8.3 million , respectively, to cover environmental remediation at various sites. The current portion of these liabilities is included in "Other accruals" 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 The CAA and comparable state laws regulate emissions of air pollutants from various industrial sources, including compressor stations, and also impose various monitoring and reporting requirements. Such laws and regulations may require pre-approval for the construction or modification of certain projects or facilities expected to produce air emissions or result in an increase of existing air emissions; application for, and strict compliance with, air permits containing various emissions and operational limitations; or the utilization of specific emission control technologies to limit emissions. The actions listed below could require further reductions in emissions from various emission sources. CPG will continue to closely monitor developments in these matters. 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 gas transmission operations. The following NAAQS were recently added or modified: Ozone : On October 1, 2015, the EPA issued a final rule lowering the NAAQS for ground-level ozone to 70 ppb under both the primary and secondary standards to provide requisite protection of public health and welfare, respectively. The EPA is required to include an adequate margin of safety in establishing the primary ozone standard for protection of public health, whereas the secondary ozone standard is intended to improve protection for trees, plants and ecosystems. The final rule becomes effective sixty days after the rule is published in the Federal Register. The EPA is required to make attainment and non-attainment designations for specific geographic locations under the revised standards by October 1, 2017 and, depending on the severity of the ozone present, non-attainment areas will have until between 2020 and 2037 to meet the health standard. With the EPA lowering the ground-level ozone standard, states may be required to implement more stringent regulations. Based on the current version of the rule, CPG does not expect a material impact on its operations. 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. Climate Change. Future legislative and regulatory programs could significantly restrict emissions of greenhouse gases including methane. New Source Performance Standards : On May 12, 2016, the EPA finalized the rule to regulate fugitive methane emissions for compressor stations in the natural gas transmission and storage sector. The final rule was subsequently published in the Federal Register on June 3, 2016. CPG is working with industry groups to litigate and clarify ambiguities within the rule. CPG does not have any existing sites that will be impacted by this rule. However, the EPA has announced that it intends to propose additional regulations related to the emission of methane from existing sources in the oil and natural gas sector. Pipeline Safety On March 17, 2016, the federal Pipeline and Hazardous Materials Safety Administration ("PHMSA") announced a proposed rulemaking that would, if adopted, impose more stringent requirements for certain gas lines and gathering lines under varying circumstances. Among other things, the proposed rulemaking would extend certain of PHMSA's current regulatory safety programs for gas pipelines beyond "high consequence areas" to cover gas pipelines found in newly defined "moderate consequence areas" that contain as few as 5 dwellings within the potential impact area; require gas pipelines installed before 1970 that are currently exempted from certain pressure testing obligations to be tested to determine their maximum allowable operating pressures ("MAOP"); and require gathering lines in Class I areas, both onshore and offshore, to comply with standards regarding damage prevention, corrosion control (for metallic pipe), public education, MAOP limits, line markers and emergency planning if such gathering lines' nominal design is 8 inches or more. In order to provide clarity and greater certainty on what may constitute a "gathering line," PHMSA is proposing a new definition of that term under the rulemaking, which term would now encompass "a pipeline, or a connected series of pipelines, and equipment used to collect gas from the endpoint of a production facility/operation and transport it to the furthermost point downstream of the following endpoints" including the "inlet of 1 st gas processing plant;" the "outlet of" a gas treatment facility (not associated with a processing plant or compressor station); the "[o]utlet of the furthermost downstream compressor" leading to a pipeline, or the "point where separate production fields are commingled." Other new requirements proposed by PHMSA under the rulemaking would require pipeline operators to: report to PHMSA in the event of certain MAOP exceedances; strengthen PHMSA integrity management requirements; consider seismicity in evaluating threats to a pipeline; conduct hydrostatic testing for all pipeline segments manufactured using longitudinal seam welds; and use more detailed guidance from PHMSA in the selection of assessment methods to inspect pipelines. CPG will continue to monitor this matter and cannot estimate the impact of these rules at this time. On June 22, 2016, President Obama signed new pipeline safety legislation, the “Protecting our Infrastructure of Pipelines and Enhancing Safety Act of 2016" (the “PIPES Act”). Extending PHMSA’s statutory mandate through 2019, the PIPES Act establishes or continues the development of stringent requirements affecting pipeline safety including: (i) providing PHMSA with additional authority to address imminent hazards by imposing emergency restrictions, prohibitions and safety measures on owners and operators of gas or hazardous liquid pipeline facilities without prior notice or an opportunity for a hearing; (ii) having pipeline operators that experience a spill from a liquids pipeline provide safety data sheets for the spilled liquid to the on-scene coordinator predesignated by the EPA and state and local officials within six hours of a telephonic notice; (iii) obligating PHMSA to develop safety standards for natural gas storage facilities by June 22, 2018; (iv) obligating PHMSA to provide feedback to pipeline operators after an inspection, including a briefing within thirty days and a written report with written preliminary findings within ninety days to the extent practicable; (v) requiring annual internal inspection of certain underwater hazardous liquid pipeline facilities in high consequence areas located at depths greater than 150 feet under the surface of the water; and (vi) requiring PHMSA to complete certain of the outstanding mandates under existing legislation and to report to Congress on the status of overdue rulemakings. CPG will continue to monitor this matter and cannot estimate the impact of these rules at this time. On October 3, 2016, PHMSA announced a temporary rule authorizing the agency to issue Emergency Orders to address what it deems imminent safety hazards for both liquid and gas pipes. The new rule allows PHMSA to impose restrictions, prohibitions, and require safety measures without giving operators prior notice or an opportunity for a hearing. In contrast to PHMSA’s past practice of issuing Corrective Action Orders to an individual owner, operator, or facility, under the new rule PHMSA can issue an Emergency Order for numerous entities. PHMSA has until March 19, 2017 to issue a permanent final rule, when this temporary rule expires. CPG will continue to monitor this matter and cannot estimate the impact of these rules at this time. Waste CPG has liabilities associated with the cleanup of various 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 $6.3 million and $6.5 million at September 30, 2016 and December 31, 2015 , respectively. The liability represents CPG's best estimate of the cost to remediate the facilities. CPG has liabilities associated with the remaining PCB remediation of its existing facilities. The total liability related to these sites was $1.7 million and $1.8 million at September 30, 2016 and December 31, 2015 , respectively. The liability represents CPG's best estimate of the cost to remediate the facilities.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 30, 2016
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 nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, 2016 (in millions) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of July 1, 2016 $ (13.7 ) $ (12.5 ) $ (26.2 ) Other comprehensive income before reclassifications — 0.4 0.4 Amounts reclassified from accumulated other comprehensive income 0.3 (0.8 ) (0.5 ) Net current-period other comprehensive income 0.3 (0.4 ) (0.1 ) Balance as of September 30, 2016 $ (13.4 ) $ (12.9 ) $ (26.3 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits. Nine Months Ended September 30, 2016 (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, 2016 $ (14.3 ) $ (12.7 ) $ (27.0 ) Other comprehensive income before reclassifications — 0.6 0.6 Amounts reclassified from accumulated other comprehensive income (2) 1.0 (0.8 ) 0.2 Net current-period other comprehensive income 1.0 (0.2 ) 0.8 Allocation of accumulated other comprehensive loss to noncontrolling interest 0.1 — 0.1 Balance as of September 30, 2016 $ (13.4 ) $ (12.9 ) $ (26.3 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits. (2) Includes amounts allocated to noncontrolling interest. Three Months Ended September 30, 2015 (in millions) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated (1) Balance as of July 1, 2015 $ (13.9 ) $ (10.6 ) $ (24.5 ) Other comprehensive income before reclassifications (0.9 ) (1.4 ) (2.3 ) Amounts reclassified from accumulated other comprehensive income 0.2 1.3 1.5 Net current-period other comprehensive income (0.7 ) (0.1 ) (0.8 ) Balance as of September 30, 2015 $ (14.6 ) $ (10.7 ) $ (25.3 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits. Nine Months Ended September 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 (0.9 ) 5.8 4.9 Amounts reclassified from accumulated other comprehensive income (2) 0.7 1.4 2.1 Net current-period other comprehensive income (0.2 ) 7.2 7.0 Allocation of accumulated other comprehensive loss to noncontrolling interest 2.2 — 2.2 Balance as of September 30, 2015 $ (14.6 ) $ (10.7 ) $ (25.3 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits. (2) Includes amounts allocated to noncontrolling interest. 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 September 30, 2016 of $13.4 million , after tax, related to terminated interest rate swaps is being amortized over a 15 year 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 $13.4 million and $14.3 million , after tax, at September 30, 2016 and December 31, 2015 , respectively, is included in gains and losses on cash flow hedges above.

Other, Net

Other, Net	9 Months Ended
	Sep. 30, 2016
Other Income and Expenses [Abstract]
Other, Net	Other, Net Three Months Ended Nine Months Ended (in millions) 2016 2015 2016 2015 AFUDC Equity $ 13.8 $ 6.5 $ 29.7 $ 15.0 Miscellaneous (0.1 ) 0.2 0.8 1.6 Total Other, net $ 13.7 $ 6.7 $ 30.5 $ 16.6

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	9 Months Ended
	Sep. 30, 2016
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 Cash Flows (unaudited) for the nine months ended September 30, 2016 and 2015 : (in millions) 2016 2015 Supplemental Disclosures of Cash Flow Information Non-cash transactions: Capital expenditures included in current liabilities (1) $ 212.2 $ 219.9 Schedule of interest and income taxes paid: Cash paid for interest, net of interest capitalized amounts $ 54.9 $ 41.9 Cash paid for income taxes (2) 3.6 30.8 (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 Sheets (unaudited). (2) Cash paid for income taxes for the nine months ended September 30, 2015 includes $20.9 million paid to NiSource under the Tax Allocation Agreement.

Concentration of Credit Risk

Concentration of Credit Risk	9 Months Ended
	Sep. 30, 2016
Risks and Uncertainties [Abstract]
Concentration Risk Disclosure	Concentration of Credit Risk Columbia Gas of Ohio, an affiliated party prior to the Separation, accounted for greater than 10% of total operating revenues for the three and nine months ended September 30, 2016 and 2015 . The following tables provide this customer's operating revenues and percentage of total operating revenues for the three and nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, 2016 2015 (in millions) Total Operating Revenues Percentage of Total Operating Revenues Total Operating Revenues Percentage of Total Operating Revenues Columbia Gas of Ohio (1) $ 35.6 10.9 % $ 35.3 11.0 % Nine Months Ended September 30, 2016 2015 (in millions) Total Operating Revenues Percentage of Total Operating Revenues Total Operating Revenues Percentage of Total Operating Revenues Columbia Gas of Ohio (1) $ 121.1 12.0 % $ 120.4 12.3 % (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 CPG receives from Columbia Gas of Ohio in any given period. The loss of a significant portion of operating revenues from this customer could have a material adverse effect on the business of CPG.

Condensed Consolidating Financi

Condensed Consolidating Financial Statements	9 Months Ended
	Sep. 30, 2016
Guarantees [Abstract]
Condensed Consolidating Financial Statements	Condensed Consolidating Financial Information On May 22, 2015, CPG closed its private placement of $2,750.0 million in aggregated principal amount of its senior notes (the "Notes"). Please see Note 7, "Long-Term Debt" for further discussion of the Notes. The Notes are fully and unconditionally guaranteed, jointly and severally, on a senior unsecured basis by three of CPG's subsidiaries, CEG, Columbia OpCo and OpCo GP. CEG is a 100% owned subsidiary of CPG. In lieu of providing separate financial statements for CEG, the accompanying condensed consolidating financial statements based on Rule 3-10 of the SEC's Regulation S-X have been included. The following supplemental condensed consolidating financial information reflects CPG's separate accounts, the combined accounts of CEG and Other Subsidiaries of CEG and CPG, including guarantors Columbia OpCo and OpCo GP, the consolidating adjustments and eliminations and the Issuer's consolidated accounts for the dates and periods indicated. Separate financial statements have been provided for Columbia OpCo and OpCo GP based on Rule 3-10 of the SEC's Regulation S-X. For purposes of the following consolidating information, CPG's and CEG's investment in its subsidiaries is accounted for under the equity method of accounting. CONDENSED CONSOLIDATING BALANCE SHEETS As of September 30, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated ASSETS Current Assets Cash and cash equivalents $ 99.9 $ 23.1 $ — $ — $ 9.6 $ — $ 132.6 Accounts receivable, net — 1.0 — — 158.5 — 159.5 Accounts receivable-affiliated 577.5 487.4 — — 181.0 (1,205.2 ) 40.7 Materials and supplies, at average cost — — — — 26.4 — 26.4 Exchange gas receivable — — — — 14.3 — 14.3 Deferred property taxes — — — — 17.7 — 17.7 Prepayments and other 54.4 44.9 — — 43.0 (98.8 ) 43.5 Total Current Assets 731.8 556.4 — — 450.5 (1,304.0 ) 434.7 Investments Unconsolidated affiliates — — — — 441.4 — 441.4 Consolidated affiliates 5,347.7 7,474.6 5,948.0 — — (18,770.3 ) — Other investments — 0.3 — — 1.5 — 1.8 Total Investments 5,347.7 7,474.9 5,948.0 — 442.9 (18,770.3 ) 443.2 Property, Plant and Equipment Property, plant and equipment — — — — 10,200.5 — 10,200.5 Accumulated depreciation and amortization — — — — (3,092.8 ) — (3,092.8 ) Net Property, Plant and Equipment — — — — 7,107.7 — 7,107.7 Other Noncurrent Assets Regulatory assets — 53.9 — — 143.8 — 197.7 Goodwill — — 1,975.5 — — — 1,975.5 Notes receivable-affiliated 1,848.2 — — — — (1,848.2 ) — Postretirement and postemployment benefits assets — — — — 112.1 (0.3 ) 111.8 Deferred income taxes — — — — 70.1 (70.1 ) — Deferred charges and other 1.4 — — — 9.8 — 11.2 Total Other Noncurrent Assets 1,849.6 53.9 1,975.5 — 335.8 (1,918.6 ) 2,296.2 Total Assets $ 7,929.1 $ 8,085.2 $ 7,923.5 $ — $ 8,336.9 $ (21,992.9 ) $ 10,281.8 CONDENSED CONSOLIDATING BALANCE SHEETS (continued) As of September 30, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated LIABILITIES AND EQUITY Current Liabilities Short-term borrowings-affiliated $ 250.0 $ — $ 439.2 $ — $ 739.3 $ (1,178.5 ) $ 250.0 Accounts payable 0.1 0.1 — — 83.9 — 84.1 Accounts payable-affiliated 7.5 15.2 0.7 — 12.9 (26.7 ) 9.6 Customer deposits — — — — 16.7 — 16.7 Taxes accrued — — — — 165.9 (98.8 ) 67.1 Interest accrued 37.0 — — — 0.1 — 37.1 Exchange gas payable — — — — 14.2 — 14.2 Deferred revenue — — — — 5.6 — 5.6 Accrued capital expenditures — — — — 171.6 — 171.6 Accrued compensation and related costs — — — — 45.1 — 45.1 Other accruals 0.3 0.3 — — 100.8 — 101.4 Total Current Liabilities 294.9 15.6 439.9 — 1,356.1 (1,304.0 ) 802.5 Noncurrent Liabilities Long-term debt 2,727.7 — — — — — 2,727.7 Long-term debt-affiliated — 1,217.3 — — 630.9 (1,848.2 ) — Deferred income taxes 22.1 1,494.6 — — — (70.1 ) 1,446.6 Accrued liability for postretirement and postemployment benefits 0.2 8.7 — — 34.9 (0.3 ) 43.5 Regulatory liabilities — 10.3 — — 273.9 — 284.2 Asset retirement obligations — — — — 23.0 — 23.0 Other noncurrent liabilities — 1.3 — — 68.8 — 70.1 Total Noncurrent Liabilities 2,750.0 2,732.2 — — 1,031.5 (1,918.6 ) 4,595.1 Total Liabilities 3,044.9 2,747.8 439.9 — 2,387.6 (3,222.6 ) 5,397.6 Equity Common stock 0.1 — — — — — 0.1 Additional paid-in capital 4,013.8 — — — — — 4,013.8 Accumulated deficit (56.7 ) — — — — — (56.7 ) Net parent investment — 4,410.2 7,507.4 — 5,977.0 (17,894.6 ) — Accumulated other comprehensive loss (26.3 ) (26.1 ) (23.8 ) — (27.7 ) 77.6 (26.3 ) Total CPG Equity 3,930.9 4,384.1 7,483.6 — 5,949.3 (17,817.0 ) 3,930.9 Noncontrolling Interest 953.3 953.3 — — — (953.3 ) 953.3 Total Equity 4,884.2 5,337.4 7,483.6 — 5,949.3 (18,770.3 ) 4,884.2 Total Liabilities and Equity $ 7,929.1 $ 8,085.2 $ 7,923.5 $ — $ 8,336.9 $ (21,992.9 ) $ 10,281.8 CONDENSED CONSOLIDATING BALANCE SHEETS (continued) As of December 31, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated ASSETS Current Assets Cash and cash equivalents $ 800.0 $ 46.7 $ 1.9 $ — $ 82.3 $ — $ 930.9 Accounts receivable, net — 5.6 — — 146.8 — 152.4 Accounts receivable-affiliated 14.6 85.6 3.4 — 156.4 (260.0 ) — Materials and supplies, at average cost — — — — 32.8 — 32.8 Exchange gas receivable — — — — 19.0 — 19.0 Deferred property taxes — — — — 52.0 — 52.0 Prepayments and other 0.3 10.1 — — 43.8 (5.7 ) 48.5 Total Current Assets 814.9 148.0 5.3 — 533.1 (265.7 ) 1,235.6 Investments Unconsolidated affiliates — — — — 438.1 — 438.1 Consolidated affiliates 5,174.6 7,569.8 5,608.9 — — (18,353.3 ) — Other investments 12.0 0.3 — — 1.5 — 13.8 Total Investments 5,186.6 7,570.1 5,608.9 — 439.6 (18,353.3 ) 451.9 Property, Plant and Equipment Property, plant and equipment — — — — 9,052.3 — 9,052.3 Accumulated depreciation and amortization — — — — (2,988.6 ) — (2,988.6 ) Net Property, Plant and Equipment — — — — 6,063.7 — 6,063.7 Other Noncurrent Assets Regulatory assets — 35.1 — — 142.6 — 177.7 Goodwill — — 1,975.5 — — — 1,975.5 Notes receivable-affiliated 1,848.2 — — — — (1,848.2 ) — Postretirement and postemployment benefits assets — 0.5 — — 115.6 (0.4 ) 115.7 Deferred income taxes 18.9 — — — — (18.9 ) — Deferred charges and other 4.9 — — — 10.6 — 15.5 Total Other Noncurrent Assets 1,872.0 35.6 1,975.5 — 268.8 (1,867.5 ) 2,284.4 Total Assets $ 7,873.5 $ 7,753.7 $ 7,589.7 $ — $ 7,305.2 $ (20,486.5 ) $ 10,035.6 CONDENSED CONSOLIDATING BALANCE SHEETS (continued) As of December 31, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated LIABILITIES AND EQUITY Current Liabilities Short-term borrowings $ — $ — $ — $ — $ 15.0 $ — $ 15.0 Short-term borrowings-affiliated 99.0 — — — 134.3 (233.3 ) — Accounts payable 0.1 — — — 56.7 — 56.8 Accounts payable-affiliated 10.8 4.8 — — 11.1 (26.7 ) — Customer deposits — — — — 17.9 — 17.9 Taxes accrued — — — — 111.7 (5.7 ) 106.0 Interest accrued 9.4 — — — 0.1 — 9.5 Exchange gas payable — — — — 18.6 — 18.6 Deferred revenue — — — — 15.0 — 15.0 Accrued capital expenditures — — — — 100.1 — 100.1 Accrued compensation and related costs — — — — 51.9 — 51.9 Other accruals — 0.3 — — 69.7 — 70.0 Total Current Liabilities 119.3 5.1 — — 602.1 (265.7 ) 460.8 Noncurrent Liabilities Long-term debt 2,725.6 — — — — — 2,725.6 Long-term debt-affiliated — 1,217.3 — — 630.9 (1,848.2 ) — Deferred income taxes — 1,350.4 — — 16.6 (18.9 ) 1,348.1 Accrued liability for postretirement and postemployment benefits 0.3 8.3 — — 41.2 (0.4 ) 49.4 Regulatory liabilities — 10.5 — — 311.1 — 321.6 Asset retirement obligations — — — — 25.7 — 25.7 Other noncurrent liabilities 15.3 0.2 — — 75.9 — 91.4 Total Noncurrent Liabilities 2,741.2 2,586.7 — — 1,101.4 (1,867.5 ) 4,561.8 Total Liabilities 2,860.5 2,591.8 — — 1,703.5 (2,133.2 ) 5,022.6 Equity Common stock 4.0 — — — — — 4.0 Additional paid-in capital 4,032.7 — — — — — 4,032.7 Retained earnings 46.9 — — — — — 46.9 Net parent investment — 4,232.3 7,615.4 — 5,631.3 (17,479.0 ) — Accumulated other comprehensive loss (27.0 ) (26.8 ) (25.7 ) — (29.6 ) 82.1 (27.0 ) Total CPG Equity 4,056.6 4,205.5 7,589.7 — 5,601.7 (17,396.9 ) 4,056.6 Noncontrolling Interest 956.4 956.4 — — — (956.4 ) 956.4 Total Equity 5,013.0 5,161.9 7,589.7 — 5,601.7 (18,353.3 ) 5,013.0 Total Liabilities and Equity $ 7,873.5 $ 7,753.7 $ 7,589.7 $ — $ 7,305.2 $ (20,486.5 ) $ 10,035.6 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Three Months Ended September 30, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 270.3 $ — $ 270.3 Storage revenues — — — — 48.9 — 48.9 Other revenues — — — — 7.9 — 7.9 Total Operating Revenues — — — — 327.1 — 327.1 Operating Expenses Operation and maintenance 67.2 — — — 255.7 — 322.9 Operation and maintenance-affiliated 1.1 — — — — (1.1 ) — Depreciation and amortization — 0.2 — — 43.4 — 43.6 Gain on sale of assets — — — — (9.3 ) — (9.3 ) Impairment of long-lived assets — — — — 19.1 — 19.1 Property and other taxes — — 0.1 — 19.7 — 19.8 Total Operating Expenses 68.3 0.2 0.1 — 328.6 (1.1 ) 396.1 Equity Earnings in Unconsolidated Affiliates — — — — 16.0 — 16.0 Equity Earnings in Consolidated Affiliates 9.8 21.0 22.6 — — (53.4 ) — Operating Loss (58.5 ) 20.8 22.5 — 14.5 (52.3 ) (53.0 ) Other Income (Deductions) Interest expense (33.0 ) — — — (0.2 ) 1.8 (31.4 ) Interest expense-affiliated (0.5 ) (11.3 ) (1.1 ) — (7.6 ) 20.0 (0.5 ) Other, net 20.3 1.4 — — 13.8 (21.8 ) 13.7 Total Other Deductions, net (13.2 ) (9.9 ) (1.1 ) — 6.0 — (18.2 ) Loss before Income Taxes (71.7 ) 10.9 21.4 — 20.5 (52.3 ) (71.2 ) Income Taxes (22.1 ) (1.2 ) — — (0.3 ) 2.0 (21.6 ) Net Loss (49.6 ) 12.1 21.4 — 20.8 (54.3 ) (49.6 ) Less: Net income attributable to noncontrolling interest 2.9 2.9 — — — (2.9 ) 2.9 Net Loss Attributable to CPG $ (52.5 ) $ 9.2 $ 21.4 $ — $ 20.8 $ (51.4 ) $ (52.5 ) CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (continued) Three Months Ended September 30, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 266.2 $ — $ 266.2 Storage revenues — — — — 49.5 — 49.5 Other revenues — — — — 5.2 — 5.2 Total Operating Revenues — — — — 320.9 — 320.9 Operating Expenses Operation and maintenance 6.3 (0.4 ) — — 180.6 — 186.5 Operation and maintenance-affiliated 1.5 — — — — (1.5 ) — Depreciation and amortization — — — — 35.0 — 35.0 Gain on sale of assets — — — — (39.0 ) — (39.0 ) Impairment of long-lived assets — — — — 0.6 — 0.6 Property and other taxes — — — — 17.3 — 17.3 Total Operating Expenses 7.8 (0.4 ) — — 194.5 (1.5 ) 200.4 Equity Earnings in Unconsolidated Affiliates — — — — 15.4 — 15.4 Equity Earnings in Consolidated Affiliates 87.7 144.9 143.6 — — (376.2 ) — Operating Income 79.9 145.3 143.6 — 141.8 (374.7 ) 135.9 Other Income (Deductions) Interest expense (29.9 ) — — — (1.1 ) 1.6 (29.4 ) Interest expense-affiliated (1.6 ) (11.4 ) — — (6.6 ) 19.6 — Other, net 19.0 0.1 1.8 — 7.0 (21.2 ) 6.7 Total Other Deductions, net (12.5 ) (11.3 ) 1.8 — (0.7 ) — (22.7 ) Income from Continuing Operations before Income Taxes 67.4 134.0 145.4 — 141.1 (374.7 ) 113.2 Income Taxes (7.5 ) 45.8 — — — — 38.3 Income from Continuing Operations 74.9 88.2 145.4 — 141.1 (374.7 ) 74.9 Loss from Discontinued Operations-net of taxes (0.1 ) (0.1 ) — — — 0.1 (0.1 ) Net Income 74.8 88.1 145.4 — 141.1 (374.6 ) 74.8 Less: Net income attributable to noncontrolling interest 11.8 11.8 — — — (11.8 ) 11.8 Net Income Attributable to CPG $ 63.0 $ 76.3 $ 145.4 $ — $ 141.1 $ (362.8 ) $ 63.0 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (continued) Nine Months Ended September 30, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 838.2 $ — $ 838.2 Storage revenues — — — — 147.7 — 147.7 Other revenues — — — — 19.6 — 19.6 Total Operating Revenues — — — — 1,005.5 — 1,005.5 Operating Expenses Operation and maintenance 135.4 (0.2 ) — — 536.9 (0.2 ) 671.9 Operation and maintenance-affiliated 1.6 — — — — (1.6 ) — Depreciation and amortization — 0.6 — — 124.6 — 125.2 Gain on sale of assets — — — — (15.3 ) — (15.3 ) Impairment of long-lived assets — — — — 19.1 — 19.1 Property and other taxes 0.1 — 0.1 — 62.4 — 62.6 Total Operating Expenses 137.1 0.4 0.1 — 727.7 (1.8 ) 863.5 Equity Earnings in Unconsolidated Affiliates — — — — 48.2 — 48.2 Equity Earnings in Consolidated Affiliates 202.4 330.6 337.4 — — (870.4 ) — Operating Income 65.3 330.2 337.3 — 326.0 (868.6 ) 190.2 Other Income (Deductions) Interest expense (92.2 ) — — — (2.9 ) 3.7 (91.4 ) Interest expense-affiliated (0.5 ) (33.7 ) (1.5 ) — (21.5 ) 56.7 (0.5 ) Other, net 59.3 2.2 — — 29.4 (60.4 ) 30.5 Total Other Deductions, net (33.4 ) (31.5 ) (1.5 ) — 5.0 — (61.4 ) Income from Continuing Operations before Income Taxes 31.9 298.7 335.8 — 331.0 (868.6 ) 128.8 Income Taxes (53.7 ) 93.9 — — 1.0 2.0 43.2 Income from Continuing Operations 85.6 204.8 335.8 — 330.0 (870.6 ) 85.6 Income from Discontinued Operations-net of taxes 0.2 0.2 — — — (0.2 ) 0.2 Net Income 85.8 205.0 335.8 — 330.0 (870.8 ) 85.8 Less: Net income attributable to noncontrolling interest 27.2 27.2 — — — (27.2 ) 27.2 Net Income Attributable to CPG $ 58.6 $ 177.8 $ 335.8 $ — $ 330.0 $ (843.6 ) $ 58.6 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (continued) Nine Months Ended September 30, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 752.4 $ — $ 752.4 Transportation revenues-affiliated — — — — 47.5 — 47.5 Storage revenues — — — — 122.3 — 122.3 Storage revenues-affiliated — — — — 26.2 — 26.2 Other revenues — — — — 28.6 — 28.6 Total Operating Revenues — — — — 977.0 — 977.0 Operating Expenses Operation and maintenance 6.6 (1.2 ) — — 450.6 — 456.0 Operation and maintenance-affiliated 1.5 0.3 — — 52.6 (1.5 ) 52.9 Depreciation and amortization — — — — 101.4 — 101.4 Gain on sale of assets — — — — (52.6 ) — (52.6 ) Impairment of long-lived assets — 1.8 — — 0.6 — 2.4 Property and other taxes — — — — 55.5 — 55.5 Total Operating Expenses 8.1 0.9 — — 608.1 (1.5 ) 615.6 Equity Earnings in Unconsolidated Affiliates — — — — 44.5 — 44.5 Equity Earnings in Consolidated Affiliates 249.4 383.2 382.5 — — (1,015.1 ) — Operating Income 241.3 382.3 382.5 — 413.4 (1,013.6 ) 405.9 Other Income (Deductions) Interest expense (42.8 ) — — — (1.1 ) 1.6 (42.3 ) Interest expense-affiliated (1.9 ) (29.5 ) — — (24.3 ) 26.4 (29.3 ) Other, net 26.1 0.3 3.3 — 14.9 (28.0 ) 16.6 Total Other Deductions, net (18.6 ) (29.2 ) 3.3 — (10.5 ) — (55.0 ) Income from Continuing Operations before Income Taxes 222.7 353.1 385.8 — 402.9 (1,013.6 ) 350.9 Income Taxes (9.4 ) 103.6 — — 26.2 (1.6 ) 118.8 Income from Continuing Operations 232.1 249.5 385.8 — 376.7 (1,012.0 ) 232.1 Loss from Discontinued Operations-net of taxes (0.4 ) (0.4 ) — — — 0.4 (0.4 ) Net Income 231.7 249.1 385.8 — 376.7 (1,011.6 ) 231.7 Less: Net income attributable to noncontrolling interest 27.9 27.9 — — — (27.9 ) 27.9 Net Income Attributable to CPG $ 203.8 $ 221.2 $ 385.8 $ — $ 376.7 $ (983.7 ) $ 203.8 CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Three Months Ended September 30, 2016 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Loss $ (49.6 ) $ 12.1 $ 21.4 $ — $ 20.8 $ (54.3 ) $ (49.6 ) Other comprehensive income Net unrealized gain on cash flow hedges 0.3 (0.3 ) — — 0.6 (0.3 ) 0.3 Unrecognized pension and OPEB cost (0.4 ) (0.5 ) — — 0.1 0.4 (0.4 ) Total other comprehensive income (0.1 ) (0.8 ) — — 0.7 0.1 (0.1 ) Total Comprehensive Loss (49.7 ) 11.3 21.4 — 21.5 (54.2 ) (49.7 ) Less: Comprehensive Income-noncontrolling interest 2.9 2.9 — — — (2.9 ) 2.9 Comprehensive Loss-controlling interests $ (52.6 ) $ 8.4 $ 21.4 $ — $ 21.5 $ (51.3 ) $ (52.6 ) Three Months Ended September 30, 2015 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Income $ 74.8 $ 88.1 $ 145.4 $ — $ 141.1 $ (374.6 ) $ 74.8 Other comprehensive income Net unrealized loss on cash flow hedges (0.7 ) (1.2 ) — — 0.5 0.7 (0.7 ) Unrecognized pension and OPEB cost (0.1 ) 0.1 — — (0.2 ) 0.1 (0.1 ) Total other comprehensive income (0.8 ) (1.1 ) — — 0.3 0.8 (0.8 ) Total Comprehensive Income 74.0 87.0 145.4 — 141.4 (373.8 ) 74.0 Less: Comprehensive Income-noncontrolling interest 11.8 11.8 — — — (11.8 ) 11.8 Comprehensive Income-controlling interests $ 62.2 $ 75.2 $ 145.4 $ — $ 141.4 $ (362.0 ) $ 62.2 CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (continued) Nine Months Ended September 30, 2016 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Income $ 85.8 $ 205.0 $ 335.8 $ — $ 330.0 $ (870.8 ) $ 85.8 Other comprehensive income Net unrealized gain on cash flow hedges 1.0 (0.6 ) — — 1.6 (1.0 ) 1.0 Unrecognized pension and OPEB cost (0.2 ) (0.3 ) — — 0.1 0.2 (0.2 ) Total other comprehensive income 0.8 (0.9 ) — — 1.7 (0.8 ) 0.8 Total Comprehensive Income 86.6 204.1 335.8 — 331.7 (871.6 ) 86.6 Less: Comprehensive Income-noncontrolling interest 27.3 27.3 — — — (27.3 ) 27.3 Comprehensive Income-controlling interests $ 59.3 $ 176.8 $ 335.8 $ — $ 331.7 $ (844.3 ) $ 59.3 Nine Months Ended September 30, 2015 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Income $ 231.7 $ 249.1 $ 385.8 $ — $ 376.7 $ (1,011.6 ) $ 231.7 Other comprehensive income Net unrealized loss on cash flow hedges (0.2 ) (1.5 ) — — 1.3 0.2 (0.2 ) Unrecognized pension and OPEB benefit 7.2 7.4 — — (0.2 ) (7.2 ) 7.2 Total other comprehensive income 7.0 5.9 — — 1.1 (7.0 ) 7.0 Total Comprehensive Income 238.7 255.0 385.8 — 377.8 (1,018.6 ) 238.7 Less: Comprehensive Income-noncontrolling interest 27.9 27.9 — — — (27.9 ) 27.9 Comprehensive Income-controlling interests $ 210.8 $ 227.1 $ 385.8 $ — $ 377.8 $ (990.7 ) $ 210.8 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Nine Months Ended September 30, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Cash Flows from Operating Activities $ (174.7 ) $ 376.9 $ (0.8 ) $ — $ 521.7 $ (470.1 ) $ 253.0 Investing Activities Capital expenditures — — — — (1,095.8 ) — (1,095.8 ) Change in short-term lendings-affiliated (519.4 ) (400.5 ) 3.3 — (28.7 ) 945.3 — Proceeds from disposition of assets — — — — 9.9 — 9.9 Contributions to equity investees — — — — (6.2 ) — (6.2 ) Distributions from equity investees — — — — 1.6 — 1.6 Other investing activities 10.3 — — — (6.5 ) — 3.8 Net Cash Flows used for Investing Activities (509.1 ) (400.5 ) 3.3 — (1,125.7 ) 945.3 (1,086.7 ) Financing Activities Change in short-term borrowings — — — — (15.0 ) — (15.0 ) Change in short-term borrowings-affiliated 151.0 — 439.2 — 605.1 (945.3 ) 250.0 Payments of capital lease obligations and other debt related costs (0.6 ) — — — (1.9 ) — (2.5 ) Common stock issuances associated with the Merger 0.1 — — — — — 0.1 Quarterly distributions to unitholders — — — — (56.9 ) 56.9 — Distribution to noncontrolling interest in Columbia OpCo — — (443.6 ) — — 443.6 — Distribution to noncontrolling interest — — — — — (30.4 ) (30.4 ) Acquisition of treasury stock (6.2 ) — — — — — (6.2 ) Dividends paid - common stock (105.1 ) — — — — — (105.1 ) Dividends paid to TransCanada (55.5 ) — — — — — (55.5 ) Net Cash Flows used for Financing Activities (16.3 ) — (4.4 ) — 531.3 (475.2 ) 35.4 Change in cash and cash equivalents (700.1 ) (23.6 ) (1.9 ) — (72.7 ) — (798.3 ) Cash and cash equivalents at beginning of period 800.0 46.7 1.9 — 82.3 — 930.9 Cash and Cash Equivalents at End of Period $ 99.9 $ 23.1 $ — $ — $ 9.6 $ — $ 132.6 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (continued) Nine Months Ended September 30, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Cash Flows from Operating Activities $ 6.2 $ (24.5 ) $ 4.1 $ — $ 440.5 $ (12.1 ) $ 414.2 Investing Activities Capital expenditures — (3.8 ) — — (833.0 ) 3.8 (833.0 ) Insurance recoveries — — — — 2.1 — 2.1 Change in short-term lendings-affiliated — (33.2 ) (126.8 ) — (119.0 ) 424.5 145.5 Proceeds from disposition of assets — 2.1 — — 55.0 (3.8 ) 53.3 Contributions to equity investees — (1,217.3 ) (446.2 ) — (1.4 ) 1,663.5 (1.4 ) Distributions from equity investees — — — — 15.1 — 15.1 Other investing activities (5.2 ) — — — (19.0 ) — (24.2 ) Net Cash Flows used for Investing Activities (5.2 ) (1,252.2 ) (573.0 ) — (900.2 ) 2,088.0 (642.6 ) Financing Activities Change in short-term borrowings 225.0 — — — 20.0 — 245.0 Change in short-term borrowings-affiliated 388.8 (5.1 ) — — (211.7 ) (424.5 ) (252.5 ) Issuance of long-term debt 2,745.9 — — — — — 2,745.9 Debt related costs (23.6 ) — — — — — (23.6 ) Issuance of long-term debt-affiliated — 1,217.3 — — — — 1,217.3 Payments of long-term debt-affiliated, including current portion (1,848.2 ) — — — (957.8 ) — (2,806.0 ) Proceeds from the issuance of common units, net of offering costs — — 1,170.0 — (1.6 ) — 1,168.4 Contribution of capital from CEG — — — — 1,663.5 (1,663.5 ) — Distribution of IPO proceeds to NiSource — — (500.0 ) — — — (500.0 ) Distribution to NiSource (1,450.0 ) — — — — — (1,450.0 ) Quarterly distributions to unitholders — — — — (26.0 ) 26.0 — Distribution to noncontrolling interest in Columbia OpCo — — (69.9 ) — — 69.9 — Distribution received from Columbia OpCo — 69.9 — — — (69.9 ) — Distribution to noncontrolling interest — — — — — (13.9 ) (13.9 ) Dividends paid - common stock (39.7 ) — — — — — (39.7 ) Transfer from NiSource 0.8 (0.6 ) (13.0 ) — 13.6 — 0.8 Net Cash Flows from Financing Activities (1.0 ) 1,281.5 587.1 — 500.0 (2,075.9 ) 291.7 Change in cash and cash equivalents — 4.8 18.2 — 40.3 — 63.3 Cash and cash equivalents at beginning of period — — — — 0.5 — 0.5 Cash and Cash Equivalents at End of Period $ — $ 4.8 $ 18.2 $ — $ 40.8 $ — $ 63.8

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2016
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event Proposed Acquisition. On November 1, 2016 , CPPL announced that it had entered into an agreement and plan of merger with CPG, Pony Merger Sub LLC, a Delaware limited liability company and wholly owned subsidiary of CPG (“Pony Merger Sub”) and MLP GP. The conflicts committee of the board of directors of MLP GP (the “GP Conflicts Committee”) and the board of directors of the MLP GP (the "GP Board") approved the merger agreement and transactions contemplated by the merger agreement and determined that the merger agreement and the merger transactions are fair and reasonable to and in the best interests of CPPL and to the holders of CPPL common units unaffiliated with CPG, CEG and MLP GP (collectively, the “CPPL unaffiliated unitholders”). The GP Conflicts Committee recommended the GP Board approve the merger agreement and the merger transactions. The GP Board resolved that the merger agreement and the merger transactions be submitted to the unitholders of CPPL at a special meeting of the unitholders for approval. The GP Board recommended that the unitholders of CPPL vote in favor of the proposal to approve the merger agreement and the merger transactions at the special meeting of the unitholders. CPG indirectly owns, through its ownership of CEG, 100.0% of the membership interests in MLP GP. CEG owns all of the subordinated units (“CPPL subordinated units”) representing a 46.5% limited partner interest in CPPL. Pursuant to the merger agreement, Pony Merger Sub will merge with and into CPPL at the effective time of the merger, with CPPL surviving, such that following the merger, MLP GP will remain a wholly owned subsidiary of CPG and the sole general partner of CPPL, and CPG and CEG will be the only limited partners of CPPL. Each CPPL common unit issued and outstanding as of immediately prior to the effective time of the merger will be converted into the right to receive (i) $ 17.00 per CPPL common unit in cash without any interest thereon plus (ii) an additional amount of cash per CPPL common unit without any interest thereon equal to the product of (x) the number of days from and including the first day of the quarter in which the closing occurs through and including the closing date multiplied by (y) $ 0.00217 per CPPL common Unit (a daily distribution rate equal to the quotient of $ 0.1975 divided by ninety-one ( 91 )), plus (iii) an amount equal to $ 0.1975 per CPPL common unit in cash without any interest thereon if the record date for the CPPL’s quarterly cash distribution with respect to the quarter immediately preceding the quarter in which the closing occurs shall not have occurred prior to the effective time of the merger (the "Merger Consideration"). Incentive distribution rights of CPPL, which are owned by CEG, will be unchanged and remain outstanding as incentive distribution rights of the surviving entity, and no consideration will be delivered in respect thereof. CPPL subordinated units, which are owned by CEG, will also be unchanged and remain outstanding as CPPL subordinated units of the surviving entity, and no consideration will be delivered in respect thereof. CPG will be issued CPPL common units at the effective time of the merger equal to the number of public common units being converted into the right to receive the Merger Consideration. The parties anticipate that the merger will close in the first quarter of 2017 and that CPPL will pay the regular quarterly cash distributions to unitholders at the quarterly per unit distribution rate of $0.1975 , with the declaration date and record date for each quarterly distribution to occur no later than 30 days and 42 days, respectively, after the end of each fiscal quarter. Completion of the merger is conditioned upon, among other things: (1) approval of the merger agreement and the transactions contemplated by the merger agreement, including the merger, by the affirmative vote or consent of holders, as of the record date of the special meeting of CPPL’s unitholders (including CEG), of (a) a majority of the outstanding CPPL common units, voting as a class, (b) a majority of the CPPL common units held by the CPPL unaffiliated unitholders, and (c) a majority of the outstanding CPPL subordinated units, voting as a class; (2) all required filings, consents, approvals, permits and authorizations in connection with the merger having been made or obtained; and (3) the absence of legal injunctions or impediments prohibiting the merger transactions. Pursuant to the merger agreement, CEG delivered a consent to voting the CPPL subordinated units owned beneficially or of record by it or any of its subsidiaries in favor of the merger proposal, including the 46,811,398 CPPL subordinated units currently held by CEG, which units represent 100.0% of the outstanding CPPL subordinated units. The merger agreement contains provisions granting both CPPL and CPG the right to terminate the merger Agreement for certain reasons, including, among others, if: (1) the merger is not completed on or before August 1, 2017; (2) any governmental authority has issued a final and nonappealable statute, rule, order, decree or regulation enjoining or prohibiting consummation of the merger; (3) under certain conditions, there has been a material breach of any of the representations, warranties, covenants or agreements set forth in the merger agreement by a party to the merger agreement which is not cured within 30 days following receipt by the breaching party of written notice from the non-breaching party (a “terminable breach”); (4) CPPL does not obtain the requisite unitholder approval of the merger agreement and the merger transactions at a special meeting of unitholders; or (5) either the GP Board, in accordance with the merger agreement, withdraws, modifies or qualifies, or proposes to publicly withdraw, modify or qualify, in a manner adverse to CPG its recommendation to the unitholders of CPPL (the “CPPL Board Recommendation”) or fails to include the CPPL Board Recommendation in the proxy statement to be filed by CPPL in connection with the merger (that taking of any such action being referred to as a “CPPL Change in Recommendation”). All costs and expenses incurred in connection with the merger agreement and the merger transactions will be paid by the party incurring such costs and expenses, except that (1) CPG and CPPL shall each bear and pay one half of the expenses incurred in connection with the proxy statement and Schedule 13E-3 filings, (2) if (a) CPG terminates the merger agreement due to a CPPL Change in Recommendation, (b) either party terminates the merger agreement due to the failure to obtain the requisite unitholder approval of the merger agreement and the merger transactions at a special meeting of unitholders of CPPL and prior to such special meeting, a CPPL Change in Recommendation has occurred, or if CPG terminates the merger agreement due to a terminable breach by CPPL, CPPL will pay the expenses incurred by CPG up to a maximum of $10.0 million , and (3) if CPPL terminates the merger agreement due to a terminable breach by CPG, CPG will pay the expenses incurred by CPPL.

CPPL Initial Public Offering (T

CPPL Initial Public Offering (Tables)	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Change From Net Income Attributable to the Partnership and Transfers to Noncontrolling Interest	Three Months Ended Nine Months Ended (in millions) 2016 2015 2016 2015 Net (loss) income attributable to CPG $ (52.5 ) $ 63.0 $ 58.6 $ 203.8 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 $ (52.5 ) $ 63.0 $ 58.6 $ 430.9

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	9 Months Ended
	Sep. 30, 2016
Asset Retirement Obligation [Abstract]
Changes In Company's Liability for Asset Retirement Obligations	(in millions) 2016 2015 Balance as of January 1, $ 25.7 $ 23.2 Accretion expense 0.8 0.9 Additions — 0.4 Settlements — — Change in estimated cash flows (3.5 ) (1.6 ) Balance as of September 30, $ 23.0 $ 22.9

Equity Method Investments (Tabl

Equity Method Investments (Tables)	9 Months Ended
	Sep. 30, 2016
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	The following table contains contribution and distribution data representing CPG's portion based on CPG's ownership percentage of each investment: Three Months Ended Nine Months Ended (in millions) 2016 2015 2016 2015 Millennium Pipeline Contributions to Millennium Pipeline $ 4.3 $ 1.4 $ 6.2 $ 1.4 Distributions of earnings from Millennium Pipeline 17.5 13.3 41.3 37.5 Hardy Storage Contributions to Hardy Storage — — — — Distributions of earnings from Hardy Storage — — 1.4 1.0 Pennant Contributions to Pennant — — — — Distributions of earnings from Pennant 2.3 2.9 8.3 5.6 Return of capital from Pennant 0.8 0.2 1.6 2.4

Pension and Other Postretirem35

Pension and Other Postretirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2016
Pension and Other Postretirement Benefit Expense [Abstract]
Components Of The Plans' Net Periodic Benefits Cost	Pension Benefits Other Postretirement Three Months Ended September 30, (in millions) 2016 2015 2016 2015 Components of Net Periodic Benefit Cost (Income) Service cost $ 1.6 $ 1.6 $ 0.2 $ 0.2 Interest cost 3.7 4.0 1.1 1.2 Expected return on assets (5.9 ) (7.0 ) (3.5 ) (4.6 ) Amortization of prior service credit (0.3 ) (0.3 ) (0.2 ) (0.2 ) Recognized actuarial loss (gain) 3.0 2.6 0.1 (0.1 ) Net Periodic Benefit Cost (Income) 2.1 0.9 (2.3 ) (3.5 ) Additional loss recognized due to: Settlement loss 2.6 — — — Total Net Periodic Benefit Cost (Income) $ 4.7 $ 0.9 $ (2.3 ) $ (3.5 ) Pension Benefits Other Postretirement Nine Months Ended September 30, (in millions) 2016 2015 2016 2015 Components of Net Periodic Benefit Cost (Income) Service cost $ 4.8 $ 4.3 $ 0.7 $ 0.8 Interest cost 11.5 11.0 3.4 3.5 Expected return on assets (19.2 ) (21.0 ) (11.6 ) (13.8 ) Amortization of prior service credit (0.9 ) (0.9 ) (0.5 ) (0.5 ) Recognized actuarial loss (gain) 9.2 7.3 0.2 (0.1 ) Net Periodic Benefit Cost (Income) 5.4 0.7 (7.8 ) (10.1 ) Additional loss recognized due to: Settlement loss 2.6 — — — Total Net Periodic Benefit Cost (Income) $ 8.0 $ 0.7 $ (7.8 ) $ (10.1 )
Schedule of Significant Actuarial Assumptions in Determining Funded Status Plan	The following table provides the key assumptions that were used to calculate the pension and other postretirement benefit obligation and the net periodic benefit cost at the measurement dates of July 1, 2016 and December 31, 2015. Pension Benefits Other Postretirement July 1, 2016 December 31, 2015 July 1, 2016 December 31, 2015 Actuarial Assumptions Discount Rate 3.75 % 4.05 % 3.95 % 4.29 % Expected return on assets 6.75 % 8.20 % 6.36 % 8.05 % Health Care Trend Rates Trend for 2016 8.81 % 8.39 % Ultimate Trend 4.50 % 4.50 % Year Ultimate Trend Reached 2023 2022

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Carrying Amount And Estimated Fair Values Of Financial Instruments	(in millions) Carrying Amount as of September 30, 2016 (1) Estimated Fair Value as of September 30, 2016 Carrying Amount as of December 31, 2015 (1) Estimated Fair Value as of December 31, 2015 Long-term debt $ 2,750.0 $ 2,987.8 $ 2,750.0 $ 2,592.1 (1) The carrying amount of the Notes differs from the Long-term debt balance on the Condensed Consolidated Balance Sheets (unaudited) due to the related unamortized discount and unamortized debt issuance costs, both of which are being amortized over the weighted average life of the Notes.

Other Commitments and Conting37

Other Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Contractual Obligation, Fiscal Year Maturity Schedule	The total guarantees and indemnities in existence at September 30, 2016 and the years in which they expire were: (in millions) Total 2016 2017 2018 2019 2020 After Other guarantees $ 45.3 $ — $ 2.4 $ — $ — $ — $ 42.9

Accumulated Other Comprehensi38

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 30, 2016
Other Comprehensive Income (Loss), Tax [Abstract]
Components Of Accumulated Other Comprehensive Loss	Three Months Ended September 30, 2016 (in millions) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of July 1, 2016 $ (13.7 ) $ (12.5 ) $ (26.2 ) Other comprehensive income before reclassifications — 0.4 0.4 Amounts reclassified from accumulated other comprehensive income 0.3 (0.8 ) (0.5 ) Net current-period other comprehensive income 0.3 (0.4 ) (0.1 ) Balance as of September 30, 2016 $ (13.4 ) $ (12.9 ) $ (26.3 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits. Nine Months Ended September 30, 2016 (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, 2016 $ (14.3 ) $ (12.7 ) $ (27.0 ) Other comprehensive income before reclassifications — 0.6 0.6 Amounts reclassified from accumulated other comprehensive income (2) 1.0 (0.8 ) 0.2 Net current-period other comprehensive income 1.0 (0.2 ) 0.8 Allocation of accumulated other comprehensive loss to noncontrolling interest 0.1 — 0.1 Balance as of September 30, 2016 $ (13.4 ) $ (12.9 ) $ (26.3 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits. (2) Includes amounts allocated to noncontrolling interest. Three Months Ended September 30, 2015 (in millions) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated (1) Balance as of July 1, 2015 $ (13.9 ) $ (10.6 ) $ (24.5 ) Other comprehensive income before reclassifications (0.9 ) (1.4 ) (2.3 ) Amounts reclassified from accumulated other comprehensive income 0.2 1.3 1.5 Net current-period other comprehensive income (0.7 ) (0.1 ) (0.8 ) Balance as of September 30, 2015 $ (14.6 ) $ (10.7 ) $ (25.3 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits. Nine Months Ended September 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 (0.9 ) 5.8 4.9 Amounts reclassified from accumulated other comprehensive income (2) 0.7 1.4 2.1 Net current-period other comprehensive income (0.2 ) 7.2 7.0 Allocation of accumulated other comprehensive loss to noncontrolling interest 2.2 — 2.2 Balance as of September 30, 2015 $ (14.6 ) $ (10.7 ) $ (25.3 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits. (2) Includes amounts allocated to noncontrolling interest.

Other, Net (Tables)

Other, Net (Tables)	9 Months Ended
	Sep. 30, 2016
Other Income and Expenses [Abstract]
Schedule Of Other, Net	Three Months Ended Nine Months Ended (in millions) 2016 2015 2016 2015 AFUDC Equity $ 13.8 $ 6.5 $ 29.7 $ 15.0 Miscellaneous (0.1 ) 0.2 0.8 1.6 Total Other, net $ 13.7 $ 6.7 $ 30.5 $ 16.6

Supplemental Cash Flow Inform40

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2016
Supplemental Cash Flow Information [Abstract]
Additional Information Regarding Condensed Statements of Consolidated Cash Flows	(in millions) 2016 2015 Supplemental Disclosures of Cash Flow Information Non-cash transactions: Capital expenditures included in current liabilities (1) $ 212.2 $ 219.9 Schedule of interest and income taxes paid: Cash paid for interest, net of interest capitalized amounts $ 54.9 $ 41.9 Cash paid for income taxes (2) 3.6 30.8 (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 Sheets (unaudited). (2) Cash paid for income taxes for the nine months ended September 30, 2015 includes $20.9 million paid to NiSource under the Tax Allocation Agreement.

Concentration of Credit Risk (T

Concentration of Credit Risk (Tables)	9 Months Ended
	Sep. 30, 2016
Risks and Uncertainties [Abstract]
Schedule of Concentration Of Credit Risk	The following tables provide this customer's operating revenues and percentage of total operating revenues for the three and nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, 2016 2015 (in millions) Total Operating Revenues Percentage of Total Operating Revenues Total Operating Revenues Percentage of Total Operating Revenues Columbia Gas of Ohio (1) $ 35.6 10.9 % $ 35.3 11.0 % Nine Months Ended September 30, 2016 2015 (in millions) Total Operating Revenues Percentage of Total Operating Revenues Total Operating Revenues Percentage of Total Operating Revenues Columbia Gas of Ohio (1) $ 121.1 12.0 % $ 120.4 12.3 % (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 CPG receives from Columbia Gas of Ohio in any given period.

Condensed Consolidating Finan42

Condensed Consolidating Financial Statements (Tables)	9 Months Ended
	Sep. 30, 2016
Guarantees [Abstract]
Guarantor - Condensed Consolidating Balance Sheets	CONDENSED CONSOLIDATING BALANCE SHEETS As of September 30, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated ASSETS Current Assets Cash and cash equivalents $ 99.9 $ 23.1 $ — $ — $ 9.6 $ — $ 132.6 Accounts receivable, net — 1.0 — — 158.5 — 159.5 Accounts receivable-affiliated 577.5 487.4 — — 181.0 (1,205.2 ) 40.7 Materials and supplies, at average cost — — — — 26.4 — 26.4 Exchange gas receivable — — — — 14.3 — 14.3 Deferred property taxes — — — — 17.7 — 17.7 Prepayments and other 54.4 44.9 — — 43.0 (98.8 ) 43.5 Total Current Assets 731.8 556.4 — — 450.5 (1,304.0 ) 434.7 Investments Unconsolidated affiliates — — — — 441.4 — 441.4 Consolidated affiliates 5,347.7 7,474.6 5,948.0 — — (18,770.3 ) — Other investments — 0.3 — — 1.5 — 1.8 Total Investments 5,347.7 7,474.9 5,948.0 — 442.9 (18,770.3 ) 443.2 Property, Plant and Equipment Property, plant and equipment — — — — 10,200.5 — 10,200.5 Accumulated depreciation and amortization — — — — (3,092.8 ) — (3,092.8 ) Net Property, Plant and Equipment — — — — 7,107.7 — 7,107.7 Other Noncurrent Assets Regulatory assets — 53.9 — — 143.8 — 197.7 Goodwill — — 1,975.5 — — — 1,975.5 Notes receivable-affiliated 1,848.2 — — — — (1,848.2 ) — Postretirement and postemployment benefits assets — — — — 112.1 (0.3 ) 111.8 Deferred income taxes — — — — 70.1 (70.1 ) — Deferred charges and other 1.4 — — — 9.8 — 11.2 Total Other Noncurrent Assets 1,849.6 53.9 1,975.5 — 335.8 (1,918.6 ) 2,296.2 Total Assets $ 7,929.1 $ 8,085.2 $ 7,923.5 $ — $ 8,336.9 $ (21,992.9 ) $ 10,281.8 CONDENSED CONSOLIDATING BALANCE SHEETS (continued) As of September 30, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated LIABILITIES AND EQUITY Current Liabilities Short-term borrowings-affiliated $ 250.0 $ — $ 439.2 $ — $ 739.3 $ (1,178.5 ) $ 250.0 Accounts payable 0.1 0.1 — — 83.9 — 84.1 Accounts payable-affiliated 7.5 15.2 0.7 — 12.9 (26.7 ) 9.6 Customer deposits — — — — 16.7 — 16.7 Taxes accrued — — — — 165.9 (98.8 ) 67.1 Interest accrued 37.0 — — — 0.1 — 37.1 Exchange gas payable — — — — 14.2 — 14.2 Deferred revenue — — — — 5.6 — 5.6 Accrued capital expenditures — — — — 171.6 — 171.6 Accrued compensation and related costs — — — — 45.1 — 45.1 Other accruals 0.3 0.3 — — 100.8 — 101.4 Total Current Liabilities 294.9 15.6 439.9 — 1,356.1 (1,304.0 ) 802.5 Noncurrent Liabilities Long-term debt 2,727.7 — — — — — 2,727.7 Long-term debt-affiliated — 1,217.3 — — 630.9 (1,848.2 ) — Deferred income taxes 22.1 1,494.6 — — — (70.1 ) 1,446.6 Accrued liability for postretirement and postemployment benefits 0.2 8.7 — — 34.9 (0.3 ) 43.5 Regulatory liabilities — 10.3 — — 273.9 — 284.2 Asset retirement obligations — — — — 23.0 — 23.0 Other noncurrent liabilities — 1.3 — — 68.8 — 70.1 Total Noncurrent Liabilities 2,750.0 2,732.2 — — 1,031.5 (1,918.6 ) 4,595.1 Total Liabilities 3,044.9 2,747.8 439.9 — 2,387.6 (3,222.6 ) 5,397.6 Equity Common stock 0.1 — — — — — 0.1 Additional paid-in capital 4,013.8 — — — — — 4,013.8 Accumulated deficit (56.7 ) — — — — — (56.7 ) Net parent investment — 4,410.2 7,507.4 — 5,977.0 (17,894.6 ) — Accumulated other comprehensive loss (26.3 ) (26.1 ) (23.8 ) — (27.7 ) 77.6 (26.3 ) Total CPG Equity 3,930.9 4,384.1 7,483.6 — 5,949.3 (17,817.0 ) 3,930.9 Noncontrolling Interest 953.3 953.3 — — — (953.3 ) 953.3 Total Equity 4,884.2 5,337.4 7,483.6 — 5,949.3 (18,770.3 ) 4,884.2 Total Liabilities and Equity $ 7,929.1 $ 8,085.2 $ 7,923.5 $ — $ 8,336.9 $ (21,992.9 ) $ 10,281.8 CONDENSED CONSOLIDATING BALANCE SHEETS (continued) As of December 31, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated ASSETS Current Assets Cash and cash equivalents $ 800.0 $ 46.7 $ 1.9 $ — $ 82.3 $ — $ 930.9 Accounts receivable, net — 5.6 — — 146.8 — 152.4 Accounts receivable-affiliated 14.6 85.6 3.4 — 156.4 (260.0 ) — Materials and supplies, at average cost — — — — 32.8 — 32.8 Exchange gas receivable — — — — 19.0 — 19.0 Deferred property taxes — — — — 52.0 — 52.0 Prepayments and other 0.3 10.1 — — 43.8 (5.7 ) 48.5 Total Current Assets 814.9 148.0 5.3 — 533.1 (265.7 ) 1,235.6 Investments Unconsolidated affiliates — — — — 438.1 — 438.1 Consolidated affiliates 5,174.6 7,569.8 5,608.9 — — (18,353.3 ) — Other investments 12.0 0.3 — — 1.5 — 13.8 Total Investments 5,186.6 7,570.1 5,608.9 — 439.6 (18,353.3 ) 451.9 Property, Plant and Equipment Property, plant and equipment — — — — 9,052.3 — 9,052.3 Accumulated depreciation and amortization — — — — (2,988.6 ) — (2,988.6 ) Net Property, Plant and Equipment — — — — 6,063.7 — 6,063.7 Other Noncurrent Assets Regulatory assets — 35.1 — — 142.6 — 177.7 Goodwill — — 1,975.5 — — — 1,975.5 Notes receivable-affiliated 1,848.2 — — — — (1,848.2 ) — Postretirement and postemployment benefits assets — 0.5 — — 115.6 (0.4 ) 115.7 Deferred income taxes 18.9 — — — — (18.9 ) — Deferred charges and other 4.9 — — — 10.6 — 15.5 Total Other Noncurrent Assets 1,872.0 35.6 1,975.5 — 268.8 (1,867.5 ) 2,284.4 Total Assets $ 7,873.5 $ 7,753.7 $ 7,589.7 $ — $ 7,305.2 $ (20,486.5 ) $ 10,035.6 CONDENSED CONSOLIDATING BALANCE SHEETS (continued) As of December 31, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated LIABILITIES AND EQUITY Current Liabilities Short-term borrowings $ — $ — $ — $ — $ 15.0 $ — $ 15.0 Short-term borrowings-affiliated 99.0 — — — 134.3 (233.3 ) — Accounts payable 0.1 — — — 56.7 — 56.8 Accounts payable-affiliated 10.8 4.8 — — 11.1 (26.7 ) — Customer deposits — — — — 17.9 — 17.9 Taxes accrued — — — — 111.7 (5.7 ) 106.0 Interest accrued 9.4 — — — 0.1 — 9.5 Exchange gas payable — — — — 18.6 — 18.6 Deferred revenue — — — — 15.0 — 15.0 Accrued capital expenditures — — — — 100.1 — 100.1 Accrued compensation and related costs — — — — 51.9 — 51.9 Other accruals — 0.3 — — 69.7 — 70.0 Total Current Liabilities 119.3 5.1 — — 602.1 (265.7 ) 460.8 Noncurrent Liabilities Long-term debt 2,725.6 — — — — — 2,725.6 Long-term debt-affiliated — 1,217.3 — — 630.9 (1,848.2 ) — Deferred income taxes — 1,350.4 — — 16.6 (18.9 ) 1,348.1 Accrued liability for postretirement and postemployment benefits 0.3 8.3 — — 41.2 (0.4 ) 49.4 Regulatory liabilities — 10.5 — — 311.1 — 321.6 Asset retirement obligations — — — — 25.7 — 25.7 Other noncurrent liabilities 15.3 0.2 — — 75.9 — 91.4 Total Noncurrent Liabilities 2,741.2 2,586.7 — — 1,101.4 (1,867.5 ) 4,561.8 Total Liabilities 2,860.5 2,591.8 — — 1,703.5 (2,133.2 ) 5,022.6 Equity Common stock 4.0 — — — — — 4.0 Additional paid-in capital 4,032.7 — — — — — 4,032.7 Retained earnings 46.9 — — — — — 46.9 Net parent investment — 4,232.3 7,615.4 — 5,631.3 (17,479.0 ) — Accumulated other comprehensive loss (27.0 ) (26.8 ) (25.7 ) — (29.6 ) 82.1 (27.0 ) Total CPG Equity 4,056.6 4,205.5 7,589.7 — 5,601.7 (17,396.9 ) 4,056.6 Noncontrolling Interest 956.4 956.4 — — — (956.4 ) 956.4 Total Equity 5,013.0 5,161.9 7,589.7 — 5,601.7 (18,353.3 ) 5,013.0 Total Liabilities and Equity $ 7,873.5 $ 7,753.7 $ 7,589.7 $ — $ 7,305.2 $ (20,486.5 ) $ 10,035.6
Guarantor - Condensed Consolidating Statements of Operations	CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Three Months Ended September 30, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 270.3 $ — $ 270.3 Storage revenues — — — — 48.9 — 48.9 Other revenues — — — — 7.9 — 7.9 Total Operating Revenues — — — — 327.1 — 327.1 Operating Expenses Operation and maintenance 67.2 — — — 255.7 — 322.9 Operation and maintenance-affiliated 1.1 — — — — (1.1 ) — Depreciation and amortization — 0.2 — — 43.4 — 43.6 Gain on sale of assets — — — — (9.3 ) — (9.3 ) Impairment of long-lived assets — — — — 19.1 — 19.1 Property and other taxes — — 0.1 — 19.7 — 19.8 Total Operating Expenses 68.3 0.2 0.1 — 328.6 (1.1 ) 396.1 Equity Earnings in Unconsolidated Affiliates — — — — 16.0 — 16.0 Equity Earnings in Consolidated Affiliates 9.8 21.0 22.6 — — (53.4 ) — Operating Loss (58.5 ) 20.8 22.5 — 14.5 (52.3 ) (53.0 ) Other Income (Deductions) Interest expense (33.0 ) — — — (0.2 ) 1.8 (31.4 ) Interest expense-affiliated (0.5 ) (11.3 ) (1.1 ) — (7.6 ) 20.0 (0.5 ) Other, net 20.3 1.4 — — 13.8 (21.8 ) 13.7 Total Other Deductions, net (13.2 ) (9.9 ) (1.1 ) — 6.0 — (18.2 ) Loss before Income Taxes (71.7 ) 10.9 21.4 — 20.5 (52.3 ) (71.2 ) Income Taxes (22.1 ) (1.2 ) — — (0.3 ) 2.0 (21.6 ) Net Loss (49.6 ) 12.1 21.4 — 20.8 (54.3 ) (49.6 ) Less: Net income attributable to noncontrolling interest 2.9 2.9 — — — (2.9 ) 2.9 Net Loss Attributable to CPG $ (52.5 ) $ 9.2 $ 21.4 $ — $ 20.8 $ (51.4 ) $ (52.5 ) CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (continued) Three Months Ended September 30, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 266.2 $ — $ 266.2 Storage revenues — — — — 49.5 — 49.5 Other revenues — — — — 5.2 — 5.2 Total Operating Revenues — — — — 320.9 — 320.9 Operating Expenses Operation and maintenance 6.3 (0.4 ) — — 180.6 — 186.5 Operation and maintenance-affiliated 1.5 — — — — (1.5 ) — Depreciation and amortization — — — — 35.0 — 35.0 Gain on sale of assets — — — — (39.0 ) — (39.0 ) Impairment of long-lived assets — — — — 0.6 — 0.6 Property and other taxes — — — — 17.3 — 17.3 Total Operating Expenses 7.8 (0.4 ) — — 194.5 (1.5 ) 200.4 Equity Earnings in Unconsolidated Affiliates — — — — 15.4 — 15.4 Equity Earnings in Consolidated Affiliates 87.7 144.9 143.6 — — (376.2 ) — Operating Income 79.9 145.3 143.6 — 141.8 (374.7 ) 135.9 Other Income (Deductions) Interest expense (29.9 ) — — — (1.1 ) 1.6 (29.4 ) Interest expense-affiliated (1.6 ) (11.4 ) — — (6.6 ) 19.6 — Other, net 19.0 0.1 1.8 — 7.0 (21.2 ) 6.7 Total Other Deductions, net (12.5 ) (11.3 ) 1.8 — (0.7 ) — (22.7 ) Income from Continuing Operations before Income Taxes 67.4 134.0 145.4 — 141.1 (374.7 ) 113.2 Income Taxes (7.5 ) 45.8 — — — — 38.3 Income from Continuing Operations 74.9 88.2 145.4 — 141.1 (374.7 ) 74.9 Loss from Discontinued Operations-net of taxes (0.1 ) (0.1 ) — — — 0.1 (0.1 ) Net Income 74.8 88.1 145.4 — 141.1 (374.6 ) 74.8 Less: Net income attributable to noncontrolling interest 11.8 11.8 — — — (11.8 ) 11.8 Net Income Attributable to CPG $ 63.0 $ 76.3 $ 145.4 $ — $ 141.1 $ (362.8 ) $ 63.0 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (continued) Nine Months Ended September 30, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 838.2 $ — $ 838.2 Storage revenues — — — — 147.7 — 147.7 Other revenues — — — — 19.6 — 19.6 Total Operating Revenues — — — — 1,005.5 — 1,005.5 Operating Expenses Operation and maintenance 135.4 (0.2 ) — — 536.9 (0.2 ) 671.9 Operation and maintenance-affiliated 1.6 — — — — (1.6 ) — Depreciation and amortization — 0.6 — — 124.6 — 125.2 Gain on sale of assets — — — — (15.3 ) — (15.3 ) Impairment of long-lived assets — — — — 19.1 — 19.1 Property and other taxes 0.1 — 0.1 — 62.4 — 62.6 Total Operating Expenses 137.1 0.4 0.1 — 727.7 (1.8 ) 863.5 Equity Earnings in Unconsolidated Affiliates — — — — 48.2 — 48.2 Equity Earnings in Consolidated Affiliates 202.4 330.6 337.4 — — (870.4 ) — Operating Income 65.3 330.2 337.3 — 326.0 (868.6 ) 190.2 Other Income (Deductions) Interest expense (92.2 ) — — — (2.9 ) 3.7 (91.4 ) Interest expense-affiliated (0.5 ) (33.7 ) (1.5 ) — (21.5 ) 56.7 (0.5 ) Other, net 59.3 2.2 — — 29.4 (60.4 ) 30.5 Total Other Deductions, net (33.4 ) (31.5 ) (1.5 ) — 5.0 — (61.4 ) Income from Continuing Operations before Income Taxes 31.9 298.7 335.8 — 331.0 (868.6 ) 128.8 Income Taxes (53.7 ) 93.9 — — 1.0 2.0 43.2 Income from Continuing Operations 85.6 204.8 335.8 — 330.0 (870.6 ) 85.6 Income from Discontinued Operations-net of taxes 0.2 0.2 — — — (0.2 ) 0.2 Net Income 85.8 205.0 335.8 — 330.0 (870.8 ) 85.8 Less: Net income attributable to noncontrolling interest 27.2 27.2 — — — (27.2 ) 27.2 Net Income Attributable to CPG $ 58.6 $ 177.8 $ 335.8 $ — $ 330.0 $ (843.6 ) $ 58.6 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (continued) Nine Months Ended September 30, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 752.4 $ — $ 752.4 Transportation revenues-affiliated — — — — 47.5 — 47.5 Storage revenues — — — — 122.3 — 122.3 Storage revenues-affiliated — — — — 26.2 — 26.2 Other revenues — — — — 28.6 — 28.6 Total Operating Revenues — — — — 977.0 — 977.0 Operating Expenses Operation and maintenance 6.6 (1.2 ) — — 450.6 — 456.0 Operation and maintenance-affiliated 1.5 0.3 — — 52.6 (1.5 ) 52.9 Depreciation and amortization — — — — 101.4 — 101.4 Gain on sale of assets — — — — (52.6 ) — (52.6 ) Impairment of long-lived assets — 1.8 — — 0.6 — 2.4 Property and other taxes — — — — 55.5 — 55.5 Total Operating Expenses 8.1 0.9 — — 608.1 (1.5 ) 615.6 Equity Earnings in Unconsolidated Affiliates — — — — 44.5 — 44.5 Equity Earnings in Consolidated Affiliates 249.4 383.2 382.5 — — (1,015.1 ) — Operating Income 241.3 382.3 382.5 — 413.4 (1,013.6 ) 405.9 Other Income (Deductions) Interest expense (42.8 ) — — — (1.1 ) 1.6 (42.3 ) Interest expense-affiliated (1.9 ) (29.5 ) — — (24.3 ) 26.4 (29.3 ) Other, net 26.1 0.3 3.3 — 14.9 (28.0 ) 16.6 Total Other Deductions, net (18.6 ) (29.2 ) 3.3 — (10.5 ) — (55.0 ) Income from Continuing Operations before Income Taxes 222.7 353.1 385.8 — 402.9 (1,013.6 ) 350.9 Income Taxes (9.4 ) 103.6 — — 26.2 (1.6 ) 118.8 Income from Continuing Operations 232.1 249.5 385.8 — 376.7 (1,012.0 ) 232.1 Loss from Discontinued Operations-net of taxes (0.4 ) (0.4 ) — — — 0.4 (0.4 ) Net Income 231.7 249.1 385.8 — 376.7 (1,011.6 ) 231.7 Less: Net income attributable to noncontrolling interest 27.9 27.9 — — — (27.9 ) 27.9 Net Income Attributable to CPG $ 203.8 $ 221.2 $ 385.8 $ — $ 376.7 $ (983.7 ) $ 203.8
Guarantor - Condensed Consolidating Statements of Comprehensive Income	CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Three Months Ended September 30, 2016 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Loss $ (49.6 ) $ 12.1 $ 21.4 $ — $ 20.8 $ (54.3 ) $ (49.6 ) Other comprehensive income Net unrealized gain on cash flow hedges 0.3 (0.3 ) — — 0.6 (0.3 ) 0.3 Unrecognized pension and OPEB cost (0.4 ) (0.5 ) — — 0.1 0.4 (0.4 ) Total other comprehensive income (0.1 ) (0.8 ) — — 0.7 0.1 (0.1 ) Total Comprehensive Loss (49.7 ) 11.3 21.4 — 21.5 (54.2 ) (49.7 ) Less: Comprehensive Income-noncontrolling interest 2.9 2.9 — — — (2.9 ) 2.9 Comprehensive Loss-controlling interests $ (52.6 ) $ 8.4 $ 21.4 $ — $ 21.5 $ (51.3 ) $ (52.6 ) Three Months Ended September 30, 2015 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Income $ 74.8 $ 88.1 $ 145.4 $ — $ 141.1 $ (374.6 ) $ 74.8 Other comprehensive income Net unrealized loss on cash flow hedges (0.7 ) (1.2 ) — — 0.5 0.7 (0.7 ) Unrecognized pension and OPEB cost (0.1 ) 0.1 — — (0.2 ) 0.1 (0.1 ) Total other comprehensive income (0.8 ) (1.1 ) — — 0.3 0.8 (0.8 ) Total Comprehensive Income 74.0 87.0 145.4 — 141.4 (373.8 ) 74.0 Less: Comprehensive Income-noncontrolling interest 11.8 11.8 — — — (11.8 ) 11.8 Comprehensive Income-controlling interests $ 62.2 $ 75.2 $ 145.4 $ — $ 141.4 $ (362.0 ) $ 62.2 CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (continued) Nine Months Ended September 30, 2016 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Income $ 85.8 $ 205.0 $ 335.8 $ — $ 330.0 $ (870.8 ) $ 85.8 Other comprehensive income Net unrealized gain on cash flow hedges 1.0 (0.6 ) — — 1.6 (1.0 ) 1.0 Unrecognized pension and OPEB cost (0.2 ) (0.3 ) — — 0.1 0.2 (0.2 ) Total other comprehensive income 0.8 (0.9 ) — — 1.7 (0.8 ) 0.8 Total Comprehensive Income 86.6 204.1 335.8 — 331.7 (871.6 ) 86.6 Less: Comprehensive Income-noncontrolling interest 27.3 27.3 — — — (27.3 ) 27.3 Comprehensive Income-controlling interests $ 59.3 $ 176.8 $ 335.8 $ — $ 331.7 $ (844.3 ) $ 59.3 Nine Months Ended September 30, 2015 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Income $ 231.7 $ 249.1 $ 385.8 $ — $ 376.7 $ (1,011.6 ) $ 231.7 Other comprehensive income Net unrealized loss on cash flow hedges (0.2 ) (1.5 ) — — 1.3 0.2 (0.2 ) Unrecognized pension and OPEB benefit 7.2 7.4 — — (0.2 ) (7.2 ) 7.2 Total other comprehensive income 7.0 5.9 — — 1.1 (7.0 ) 7.0 Total Comprehensive Income 238.7 255.0 385.8 — 377.8 (1,018.6 ) 238.7 Less: Comprehensive Income-noncontrolling interest 27.9 27.9 — — — (27.9 ) 27.9 Comprehensive Income-controlling interests $ 210.8 $ 227.1 $ 385.8 $ — $ 377.8 $ (990.7 ) $ 210.8
Guarantor - Condensed Consolidating Statements of Cash Flows	CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Nine Months Ended September 30, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Cash Flows from Operating Activities $ (174.7 ) $ 376.9 $ (0.8 ) $ — $ 521.7 $ (470.1 ) $ 253.0 Investing Activities Capital expenditures — — — — (1,095.8 ) — (1,095.8 ) Change in short-term lendings-affiliated (519.4 ) (400.5 ) 3.3 — (28.7 ) 945.3 — Proceeds from disposition of assets — — — — 9.9 — 9.9 Contributions to equity investees — — — — (6.2 ) — (6.2 ) Distributions from equity investees — — — — 1.6 — 1.6 Other investing activities 10.3 — — — (6.5 ) — 3.8 Net Cash Flows used for Investing Activities (509.1 ) (400.5 ) 3.3 — (1,125.7 ) 945.3 (1,086.7 ) Financing Activities Change in short-term borrowings — — — — (15.0 ) — (15.0 ) Change in short-term borrowings-affiliated 151.0 — 439.2 — 605.1 (945.3 ) 250.0 Payments of capital lease obligations and other debt related costs (0.6 ) — — — (1.9 ) — (2.5 ) Common stock issuances associated with the Merger 0.1 — — — — — 0.1 Quarterly distributions to unitholders — — — — (56.9 ) 56.9 — Distribution to noncontrolling interest in Columbia OpCo — — (443.6 ) — — 443.6 — Distribution to noncontrolling interest — — — — — (30.4 ) (30.4 ) Acquisition of treasury stock (6.2 ) — — — — — (6.2 ) Dividends paid - common stock (105.1 ) — — — — — (105.1 ) Dividends paid to TransCanada (55.5 ) — — — — — (55.5 ) Net Cash Flows used for Financing Activities (16.3 ) — (4.4 ) — 531.3 (475.2 ) 35.4 Change in cash and cash equivalents (700.1 ) (23.6 ) (1.9 ) — (72.7 ) — (798.3 ) Cash and cash equivalents at beginning of period 800.0 46.7 1.9 — 82.3 — 930.9 Cash and Cash Equivalents at End of Period $ 99.9 $ 23.1 $ — $ — $ 9.6 $ — $ 132.6 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (continued) Nine Months Ended September 30, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Cash Flows from Operating Activities $ 6.2 $ (24.5 ) $ 4.1 $ — $ 440.5 $ (12.1 ) $ 414.2 Investing Activities Capital expenditures — (3.8 ) — — (833.0 ) 3.8 (833.0 ) Insurance recoveries — — — — 2.1 — 2.1 Change in short-term lendings-affiliated — (33.2 ) (126.8 ) — (119.0 ) 424.5 145.5 Proceeds from disposition of assets — 2.1 — — 55.0 (3.8 ) 53.3 Contributions to equity investees — (1,217.3 ) (446.2 ) — (1.4 ) 1,663.5 (1.4 ) Distributions from equity investees — — — — 15.1 — 15.1 Other investing activities (5.2 ) — — — (19.0 ) — (24.2 ) Net Cash Flows used for Investing Activities (5.2 ) (1,252.2 ) (573.0 ) — (900.2 ) 2,088.0 (642.6 ) Financing Activities Change in short-term borrowings 225.0 — — — 20.0 — 245.0 Change in short-term borrowings-affiliated 388.8 (5.1 ) — — (211.7 ) (424.5 ) (252.5 ) Issuance of long-term debt 2,745.9 — — — — — 2,745.9 Debt related costs (23.6 ) — — — — — (23.6 ) Issuance of long-term debt-affiliated — 1,217.3 — — — — 1,217.3 Payments of long-term debt-affiliated, including current portion (1,848.2 ) — — — (957.8 ) — (2,806.0 ) Proceeds from the issuance of common units, net of offering costs — — 1,170.0 — (1.6 ) — 1,168.4 Contribution of capital from CEG — — — — 1,663.5 (1,663.5 ) — Distribution of IPO proceeds to NiSource — — (500.0 ) — — — (500.0 ) Distribution to NiSource (1,450.0 ) — — — — — (1,450.0 ) Quarterly distributions to unitholders — — — — (26.0 ) 26.0 — Distribution to noncontrolling interest in Columbia OpCo — — (69.9 ) — — 69.9 — Distribution received from Columbia OpCo — 69.9 — — — (69.9 ) — Distribution to noncontrolling interest — — — — — (13.9 ) (13.9 ) Dividends paid - common stock (39.7 ) — — — — — (39.7 ) Transfer from NiSource 0.8 (0.6 ) (13.0 ) — 13.6 — 0.8 Net Cash Flows from Financing Activities (1.0 ) 1,281.5 587.1 — 500.0 (2,075.9 ) 291.7 Change in cash and cash equivalents — 4.8 18.2 — 40.3 — 63.3 Cash and cash equivalents at beginning of period — — — — 0.5 — 0.5 Cash and Cash Equivalents at End of Period $ — $ 4.8 $ 18.2 $ — $ 40.8 $ — $ 63.8

Basis of Accounting Presentat43

Basis of Accounting Presentation (Narrative) (Details) $ / shares in Units, shares in Millions, $ in Millions	Jul. 01, 2016USD ($)$ / shares	Sep. 30, 2016USD ($)mi$ / shares	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)mi$ / shares	Sep. 30, 2015USD ($)	Dec. 31, 2015$ / shares	Jul. 01, 2015shares	May 22, 2015USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Pipeline Miles | mi		15,000		15,000
Common Stock, Shares, Issued | shares							317.6
Senior notes proceeds								$ 2,722.3
Repayments of Related Party Debt					$ 1,087.3
Distribution to NiSource				$ 0	1,450
Business Acquisition, Effective Date of Acquisition	Jul. 1, 2016
Business Combination, Consideration Transferred	$ 13,000
Purchase Price	10,300
Debt Assumed	$ 2,700
Common Stock, Par or Stated Value Per Share | $ / shares	$ 0.01	$ 0.01		$ 0.01		$ 0.01
Business Acquisition, Share Price | $ / shares	$ 25.50
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	46.50%
Merger related transaction costs		$ 43.1		$ 66.3
Employee related Merger transaction costs				101.5
Impairment of long-lived assets		$ 19.1	$ 0.6	$ 19.1	$ 2.4

CPPL Initial Public Offering (N

CPPL Initial Public Offering (Narrative) (Details) - USD ($) shares in Millions, $ in Millions	Jul. 01, 2016	Sep. 30, 2015
Initial Public Offering [Line Items]
Issuance of common units of CPPL		$ 1,168.4
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	46.50%
Columbia Pipeline Partners LP
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		15.70%
Noncontrolling Interest
Initial Public Offering [Line Items]
Issuance of common units of CPPL		$ 1,168.4
Common Units | Noncontrolling Interest
Initial Public Offering [Line Items]
Partners' Capital Account, Units, Sold in Public Offering		53.8

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) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Initial Public Offering [Line Items]
Net (loss) income attributable to CPG	$ (52.5)	$ 63	$ 58.6	$ 203.8
Increase for sale of limited partner interest	0	0	0	227.1
Change from net income attributable to parent and transfers to noncontrolling interest	$ (52.5)	$ 63	$ 58.6	$ 430.9

Recent Accounting Pronounceme46

Recent Accounting Pronouncements (Narrative) (Details) $ in Millions	Dec. 31, 2015USD ($)
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Unamortized debt issuance costs	$ 20.6
New Accounting Pronouncement, Cumulative Effect of Change on Net Assets	$ 20.6

Transactions with Affiliates (N

Transactions with Affiliates (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	May 10, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 05, 2014
Related Party Transaction [Line Items]
Interest Expense, Short-term Borrowings				$ 0.5
Accounts receivable-affiliated		$ 40.7		40.7		$ 0
Accounts payable-affiliated		9.6		9.6		0
Dividend to TransCanada				55.5
Common Stock, Dividends, Per Share, Declared	$ 0.13875
Transportation revenues-affiliated		0	$ 0	0	$ 47.5
Storage revenues-affiliated		0	0	0	26.2
Other revenues					0.2
Operation and maintenance-affiliated		0	$ 0	0	52.9
Interest Expense, Long-term Debt					31
Allowance for Funds Used During Construction, Capitalized Interest					2.4
Distribution to NiSource				$ 0	1,450
Columbia OpCo
Related Party Transaction [Line Items]
Reimbursement of preformation capital					500
Federal Funds Effective Swap Rate
Related Party Transaction [Line Items]
Debt Instrument, Basis Spread on Variable Rate				0.50%
London Interbank Offered Rate (LIBOR)
Related Party Transaction [Line Items]
Debt Instrument, Basis Spread on Variable Rate				1.00%
Margin Rate				0.25%
Eurodollar
Related Party Transaction [Line Items]
Margin Rate				1.25%
Revolving Credit Facility
Related Party Transaction [Line Items]
Revolving credit facility, Maximum Borrowing Capacity							$ 1,500
Long-term Line of Credit						$ 0
Money Pool
Related Party Transaction [Line Items]
Interest Expense, Short-term Borrowings					$ 0.7
Short-Term Borrowings, Weighted Average Interest Rate			1.21%		1.21%
Interest income					$ 2.5
TransCanada PipeLine USA Ltd. | Revolving Credit Facility
Related Party Transaction [Line Items]
Revolving credit facility, Maximum Borrowing Capacity		2,000		$ 2,000
Long-term Line of Credit		$ 250		$ 250
Short-Term Borrowings, Weighted Average Interest Rate		1.87%		1.87%

Short-Term Borrowings (Narrativ

Short-Term Borrowings (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Dec. 05, 2014
Revolving Credit Facility
Short-term Debt [Line Items]
Revolving credit facility, Maximum Borrowing Capacity				$ 1,500
Line of Credit			$ 0
Accelerated amortization of deferred costs	$ 4.3
Letter of Credit
Short-term Debt [Line Items]
Revolving credit facility, Maximum Borrowing Capacity				250
Letters of Credit Outstanding, Amount			18.1
Commercial Paper
Short-term Debt [Line Items]
Revolving credit facility, Maximum Borrowing Capacity		$ 1,000
Commercial Paper		$ 0	0
Columbia Pipeline Partners LP | Revolving Credit Facility
Short-term Debt [Line Items]
Revolving credit facility, Maximum Borrowing Capacity				500
Line of Credit			$ 15
Short-Term Borrowings, Weighted Average Interest Rate			1.28%
Accelerated amortization of deferred costs	$ 1.4
Columbia Pipeline Partners LP | Letter of Credit
Short-term Debt [Line Items]
Revolving credit facility, Maximum Borrowing Capacity				$ 50
Letters of Credit Outstanding, Amount			$ 0

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - Senior Notes - USD ($) $ in Millions	May 22, 2015	Sep. 30, 2016
Debt Instrument [Line Items]
Debt Instrument, Issuance Date	May 22, 2015
Face amount of notes		$ 2,750
Notes Due 2018
Debt Instrument [Line Items]
Face amount of notes	$ 500
Debt Instrument, Interest Rate, Stated Percentage	2.45%
Debt Instrument, Maturity Date	Jun. 1, 2018
Notes Due 2020
Debt Instrument [Line Items]
Face amount of notes	$ 750
Debt Instrument, Interest Rate, Stated Percentage	3.30%
Debt Instrument, Maturity Date	Jun. 1, 2020
Notes Due 2025
Debt Instrument [Line Items]
Face amount of notes	$ 1,000
Debt Instrument, Interest Rate, Stated Percentage	4.50%
Debt Instrument, Maturity Date	Jun. 1, 2025
Notes Due 2045
Debt Instrument [Line Items]
Face amount of notes	$ 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		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Gain On Sale of Assets [Abstract]
Gain on Conveyances	$ 9.7	$ 36	$ 15.7	$ 49.6
Gain on Conveyances Cash Received			9	$ 35.8
Deferred Gains On Conveyances	$ 1.3		$ 1.3		$ 8.1

Goodwill (Narrative) (Details)

Goodwill (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
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	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning Balance	$ 25.7	$ 23.2
Accretion expense	0.8	0.9
Additions	0	0.4
Settlements	0	0
Change in estimated cash flows	(3.5)	(1.6)
Ending Balance	$ 23	$ 22.9

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions	Jan. 01, 2016	Sep. 30, 2016	Feb. 01, 2016
Regulatory Assets and Liabilities Disclosure [Abstract]
Expected Modernization Investment	$ 300
Modernization Program Recovery			$ 320
Annual Capital Cost Recovery Mechanism Extension Limit		$ 1,100

Equity Method Investments (Narr

Equity Method Investments (Narrative) (Details) - Pennant $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Initial Ownership Percentage	5.00%
Equity Method Investment, Ownership Percentage	47.50%
Cash Received from Buy-In	$ 12.7
Gain on Buy-In	$ 2.9
Maximum
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	33.33%
Previous
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%

Equity Method Investments (Sche

Equity Method Investments (Schedule of Equity Method Investments) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Millennium Pipeline
Schedule of Equity Method Investments [Line Items]
Contributions to equity investees	$ 4.3	$ 1.4	$ 6.2	$ 1.4
Distributions of earnings from equity investees	17.5	13.3	41.3	37.5
Hardy Storage
Schedule of Equity Method Investments [Line Items]
Contributions to equity investees	0	0	0	0
Distributions of earnings from equity investees	0	0	1.4	1
Pennant
Schedule of Equity Method Investments [Line Items]
Contributions to equity investees	0	0	0	0
Distributions of earnings from equity investees	2.3	2.9	8.3	5.6
Return of capital from equity investees	$ 0.8	$ 0.2	$ 1.6	$ 2.4

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Effective income tax rates	30.30%	33.80%	33.50%	33.90%
Federal statutory income tax rate			35.00%	35.00%

Pension and Other Postretirem57

Pension and Other Postretirement Benefits (Narrative) (Details) - USD ($) $ in Millions	Jul. 01, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Contributions by Employer				$ 0
Change in Projected Benefit Obligation, Net of Plan Assets, Due to Interim Measurement	$ (4.9)
Decrease in regulatory assets due to interim measurement	1.2
Change in Accumulated Other Comprehensive Income Due to Interim Measurement	(0.3)
Change in Net Periodic Benefit Cost due to Interim Measurement	0.9
Settlement loss		$ (2.6)	$ 0	(2.6)	$ 0
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Contributions by Employer				1.6
Change in Projected Benefit Obligation, Net of Plan Assets, Due to Interim Measurement	(11.2)
Increase in regulatory assets due to interim measurement	8.6
Decrease in regulatory liabilities due to interim measurement	1.8
Change in Accumulated Other Comprehensive Income Due to Interim Measurement	(0.5)
Change in Net Periodic Benefit Cost due to Interim Measurement	$ 1.1
Settlement loss		$ 0	$ 0	$ 0	$ 0

Pension and Other Postretirem58

Pension and Other Postretirement Benefits (Components Of The Plans' Net Periodic Benefits Cost) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1.6	$ 1.6	$ 4.8	$ 4.3
Interest cost	3.7	4	11.5	11
Expected return on assets	(5.9)	(7)	(19.2)	(21)
Amortization of prior service credit	(0.3)	(0.3)	(0.9)	(0.9)
Recognized actuarial loss (gain)	3	2.6	9.2	7.3
Net Periodic Benefit Cost	2.1	0.9	5.4	0.7
Settlement loss	2.6	0	2.6	0
Total Net Periodic Benefit Cost (Income)	4.7	0.9	8	0.7
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.2	0.2	0.7	0.8
Interest cost	1.1	1.2	3.4	3.5
Expected return on assets	(3.5)	(4.6)	(11.6)	(13.8)
Amortization of prior service credit	(0.2)	(0.2)	(0.5)	(0.5)
Recognized actuarial loss (gain)	0.1	(0.1)	0.2	(0.1)
Net Periodic Benefit Cost	(2.3)	(3.5)	(7.8)	(10.1)
Settlement loss	0	0	0	0
Total Net Periodic Benefit Cost (Income)	$ (2.3)	$ (3.5)	$ (7.8)	$ (10.1)

Pension and Other Postretirem59

Pension and Other Postretirement Benefits (Schedule of Significant Actuarial Assumptions in Determining Funded Status Plan) (Details)	Jul. 01, 2016	Dec. 31, 2015
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	3.75%	4.05%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	6.75%	8.20%
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	3.95%	4.29%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	6.36%	8.05%
Trend Rate for Next Year	8.81%	8.39%
Ultimate Trend	4.50%	4.50%
Year Ultimate Trend Reached	2,023	2,022

Fair Value (Carrying Amount And

Fair Value (Carrying Amount And Estimated Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Long-term debt, carrying amount	[1]	$ 2,750	$ 2,750
Long-term debt, estimated fair value		$ 2,987.8	$ 2,592.1
[1]	The carrying amount of the Notes differs from the Long-term debt balance on the Condensed Consolidated Balance Sheets (unaudited) due to the related unamortized discount and unamortized debt issuance costs, both of which are being amortized over the weighted average life of the Notes.

Share-Based Compensation (Narra

Share-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Jul. 01, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Business Acquisition, Share Price					$ 25.50
Stock-based compensation expense	$ 56.3	$ 0.1	$ 63.9	$ 3.2
Tax benefit from stock-based compensation expense	18.8	0	21.5	1.2
Defined Contribution Plan, Cost Recognized	$ 3	$ 2.2	$ 9.2	$ 6.6
CPG Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted			12,144
Grant date fair-value			$ 0.2
Nonvested	0		0
CPG Plan | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted			955,848
Grant date fair-value			$ 17
Nonvested	0		0
Omnibus Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-employee director units outstanding			0
Director Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-employee director units outstanding			0

Other Commitments and Conting62

Other Commitments and Contingencies (Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 05, 2014USD ($)
Other Commitments [Line Items]
Accrual for Environmental Loss Contingencies	$ 8		$ 8.3
Ozone Level Maximum	70 ppb
Dwellings within the potential impact area	5
Gathering line nominal design inches	8
Feet under the surface water	150
Senior Notes
Other Commitments [Line Items]
Face amount of notes	$ 2,750
Revolving Credit Facility
Other Commitments [Line Items]
Revolving credit facility, Maximum Borrowing Capacity				$ 1,500
Line of Credit			0
Revolving Credit Facility | Columbia Pipeline Partners LP
Other Commitments [Line Items]
Revolving credit facility, Maximum Borrowing Capacity				500
Line of Credit			15
Letter of Credit
Other Commitments [Line Items]
Revolving credit facility, Maximum Borrowing Capacity				250
Letters of Credit Outstanding, Amount			18.1
Letter of Credit | Columbia Pipeline Partners LP
Other Commitments [Line Items]
Revolving credit facility, Maximum Borrowing Capacity				$ 50
Letters of Credit Outstanding, Amount			0
Commercial Paper
Other Commitments [Line Items]
Revolving credit facility, Maximum Borrowing Capacity		$ 1,000
Commercial Paper		$ 0	0
Guarantee Type, Other
Other Commitments [Line Items]
Guarantor Obligations, Maximum Exposure	45.3
Former Propane and Petroleum Operations
Other Commitments [Line Items]
Liability for Estimated Remediation Costs	6.3		6.5
PCB
Other Commitments [Line Items]
Liability for Estimated Remediation Costs	$ 1.7		$ 1.8

Other Commitments and Conting63

Other Commitments and Contingencies (Existence and Expiration of Commercial Commitments) (Details) - Guarantee Type, Other $ in Millions	Sep. 30, 2016USD ($)
Other Commitments and Contingencies [Line Items]
2,016	$ 0
2,017	2.4
2,018	0
2,019	0
2,020	0
Thereafter	42.9
Total	$ 45.3

Accumulated Other Comprehensi64

Accumulated Other Comprehensive Loss (Narrative) (Details) - Millennium Pipeline - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Loss [Line Items]
Other Comprehensive Income Unrecognized Gain Loss On Derivatives Arising During Period Net Of Tax	$ 13.4	$ 14.3
Unrealized loss, amortization period	15 years
Debt Instrument, Maturity Date	Jun. 1, 2025

Accumulated Other Comprehensi65

Accumulated Other Comprehensive Loss (Components Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	$ (26.2)	$ (24.5)	$ (27)	$ (34.5)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]	0.4	(2.3)	0.6	4.9
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]	(0.5)	1.5	0.2	2.1
Other Comprehensive Income (Loss), Net of Tax	[1]	(0.1)	(0.8)	0.8	7
Ending Balance	[1]	(26.3)	(25.3)	(26.3)	(25.3)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(13.7)	(13.9)	(14.3)	(16.6)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]	0	(0.9)	0	(0.9)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]	0.3	0.2	1	0.7
Other Comprehensive Income (Loss), Net of Tax	[1]	0.3	(0.7)	1	(0.2)
Ending Balance	[1]	(13.4)	(14.6)	(13.4)	(14.6)
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(12.5)	(10.6)	(12.7)	(17.9)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]	0.4	(1.4)	0.6	5.8
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1],[2]	(0.8)	1.3	(0.8)	1.4
Other Comprehensive Income (Loss), Net of Tax	[1]	(0.4)	(0.1)	(0.2)	7.2
Ending Balance	[1]	$ (12.9)	$ (10.7)	(12.9)	(10.7)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Net of Tax	[1]			0.1	2.2
Accumulated Defined Benefit Plans Adjustment Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Net of Tax	[1]			0	0
AOCI Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Net of Tax	[1]			$ 0.1	$ 2.2
[1]	All amounts are net of tax. Amounts in parentheses indicate debits.
[2]	Includes amounts allocated to noncontrolling interest.

Other, Net (Schedule of Other,

Other, Net (Schedule of Other, Net) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Other Income and Expenses [Abstract]
AFUDC Equity	$ 13.8	$ 6.5	$ 29.7	$ 15
Miscellaneous	(0.1)	0.2	0.8	1.6
Total Other, net	$ 13.7	$ 6.7	$ 30.5	$ 16.6

Supplemental Cash Flow Inform67

Supplemental Cash Flow Information (Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2015USD ($)
Supplemental Cash Flow Elements [Abstract]
Cash Paid for Taxes Under Tax Allocation Agreement	$ 20.9

Supplemental Cash Flow Inform68

Supplemental Cash Flow Information (Schedule of Supplemental Cash Flow Information) (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015
Supplemental Cash Flow Information [Abstract]
Capital expenditures included in current liabilities	[1]	$ 212.2	$ 219.9
Cash paid for interest, net of interest capitalized amounts		54.9	41.9
Cash paid for income taxes		$ 3.6	$ 30.8	[2]
[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 Sheets (unaudited).
[2]	Cash paid for income taxes for the nine months ended September 30, 2015 includes $20.9 million paid to NiSource under the Tax Allocation Agreement.

Concentration of Credit Risk (N

Concentration of Credit Risk (Narrative) (Details)	9 Months Ended
	Sep. 30, 2016
Risks and Uncertainties [Abstract]
Concentration Risk, Benchmark Description	10% of total operating revenues

Concentration of Credit Risk (S

Concentration of Credit Risk (Schedule of Concentration Of Credit Risk) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Concentration Risk [Line Items]
Revenues		$ 327.1	$ 320.9	$ 1,005.5	$ 977
Credit Concentration Risk
Concentration Risk [Line Items]
Revenues	[1]	$ 35.6	$ 35.3	$ 121.1	$ 120.4
Concentration Risk, Percentage	[1]	10.90%	11.00%	12.00%	12.30%
[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 CPG receives from Columbia Gas of Ohio in any given period.

Condensed Consolidating Finan71

Condensed Consolidating Financial Statements (Narrative) (Details) $ in Millions	Sep. 30, 2016USD ($)
Senior Notes
Guarantor Obligations [Line Items]
Face amount of notes	$ 2,750

Condensed Consolidating Finan72

Condensed Consolidating Financial Statements (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Millions		Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Current Assets
Cash and cash equivalents		$ 132.6		$ 930.9	$ 63.8		$ 0.5
Accounts receivable, net		159.5		152.4
Accounts receivable-affiliated		40.7		0
Materials and supplies, at average cost		26.4		32.8
Exchange gas receivable		14.3		19
Deferred property taxes		17.7		52
Prepayments and other		43.5		48.5
Total Current Assets		434.7		1,235.6
Investments
Unconsolidated affiliates		441.4		438.1
Consolidated affiliates		0		0
Other investments		1.8		13.8
Total Investments		443.2		451.9
Property, Plant and Equipment
Property, plant and equipment		10,200.5		9,052.3
Accumulated depreciation and amortization		(3,092.8)		(2,988.6)
Net Property, Plant and Equipment		7,107.7		6,063.7
Other Noncurrent Assets
Regulatory assets		197.7		177.7
Goodwill		1,975.5		1,975.5
Notes receivable-affiliated		0		0
Postretirement and postemployment benefits assets		111.8		115.7
Deferred income taxes		0		0
Deferred charges and other		11.2		15.5
Total Other Noncurrent Assets		2,296.2		2,284.4
Total Assets		10,281.8		10,035.6
Current Liabilities
Short-term borrowings		0		15
Short-term borrowings-affiliated		250		0
Accounts payable		84.1		56.8
Accounts payable-affiliated		9.6		0
Customer deposits		16.7		17.9
Taxes accrued		67.1		106
Interest accrued		37.1		9.5
Exchange gas payable		14.2		18.6
Deferred revenue		5.6		15
Accrued capital expenditures		171.6		100.1
Accrued compensation and related costs		45.1		51.9
Other accruals		101.4		70
Total Current Liabilities		802.5		460.8
Noncurrent Liabilities
Long-term debt		2,727.7		2,725.6
Long-term debt-affiliated		0		0
Deferred income taxes		1,446.6		1,348.1
Accrued liability for postretirement and postemployment benefits		43.5		49.4
Regulatory liabilities		284.2		321.6
Asset retirement obligations		23		25.7	22.9		23.2
Other noncurrent liabilities		70.1		91.4
Total Noncurrent Liabilities		4,595.1		4,561.8
Total Liabilities		5,397.6		5,022.6
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,000 and 399,841,350 shares outstanding, respectively		0.1		4
Additional paid-in capital		4,013.8		4,032.7
(Accumulated deficit) Retained earnings		(56.7)		46.9
Net parent investment		0		0
Accumulated other comprehensive loss	[1]	(26.3)	$ (26.2)	(27)	(25.3)	$ (24.5)	(34.5)
Total CPG Equity		3,930.9		4,056.6
Noncontrolling Interest		953.3		956.4
Total Equity		4,884.2		5,013	3,549.6		4,176.3
Total Liabilities and Equity		10,281.8		10,035.6
Consolidating adjustments and eliminations
Current Assets
Cash and cash equivalents		0		0	0		0
Accounts receivable, net		0		0
Accounts receivable-affiliated		(1,205.2)		(260)
Materials and supplies, at average cost		0		0
Exchange gas receivable		0		0
Deferred property taxes		0		0
Prepayments and other		(98.8)		(5.7)
Total Current Assets		(1,304)		(265.7)
Investments
Unconsolidated affiliates		0		0
Consolidated affiliates		(18,770.3)		(18,353.3)
Other investments		0		0
Total Investments		(18,770.3)		(18,353.3)
Property, Plant and Equipment
Property, plant and equipment		0		0
Accumulated depreciation and amortization		0		0
Net Property, Plant and Equipment		0		0
Other Noncurrent Assets
Regulatory assets		0		0
Goodwill		0		0
Notes receivable-affiliated		(1,848.2)		(1,848.2)
Postretirement and postemployment benefits assets		(0.3)		(0.4)
Deferred income taxes		(70.1)		(18.9)
Deferred charges and other		0		0
Total Other Noncurrent Assets		(1,918.6)		(1,867.5)
Total Assets		(21,992.9)		(20,486.5)
Current Liabilities
Short-term borrowings				0
Short-term borrowings-affiliated		(1,178.5)		(233.3)
Accounts payable		0		0
Accounts payable-affiliated		(26.7)		(26.7)
Customer deposits		0		0
Taxes accrued		(98.8)		(5.7)
Interest accrued		0		0
Exchange gas payable		0		0
Deferred revenue		0		0
Accrued capital expenditures		0		0
Accrued compensation and related costs		0		0
Other accruals		0		0
Total Current Liabilities		(1,304)		(265.7)
Noncurrent Liabilities
Long-term debt		0		0
Long-term debt-affiliated		(1,848.2)		(1,848.2)
Deferred income taxes		(70.1)		(18.9)
Accrued liability for postretirement and postemployment benefits		(0.3)		(0.4)
Regulatory liabilities		0		0
Asset retirement obligations		0		0
Other noncurrent liabilities		0		0
Total Noncurrent Liabilities		(1,918.6)		(1,867.5)
Total Liabilities		(3,222.6)		(2,133.2)
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,000 and 399,841,350 shares outstanding, respectively		0		0
Additional paid-in capital		0		0
(Accumulated deficit) Retained earnings		0		0
Net parent investment		(17,894.6)		(17,479)
Accumulated other comprehensive loss		77.6		82.1
Total CPG Equity		(17,817)		(17,396.9)
Noncontrolling Interest		(953.3)		(956.4)
Total Equity		(18,770.3)		(18,353.3)
Total Liabilities and Equity		(21,992.9)		(20,486.5)
Columbia Pipeline Group
Current Assets
Cash and cash equivalents		99.9		800	0		0
Accounts receivable, net		0		0
Accounts receivable-affiliated		577.5		14.6
Materials and supplies, at average cost		0		0
Exchange gas receivable		0		0
Deferred property taxes		0		0
Prepayments and other		54.4		0.3
Total Current Assets		731.8		814.9
Investments
Unconsolidated affiliates		0		0
Consolidated affiliates		5,347.7		5,174.6
Other investments		0		12
Total Investments		5,347.7		5,186.6
Property, Plant and Equipment
Property, plant and equipment		0		0
Accumulated depreciation and amortization		0		0
Net Property, Plant and Equipment		0		0
Other Noncurrent Assets
Regulatory assets		0		0
Goodwill		0		0
Notes receivable-affiliated		1,848.2		1,848.2
Postretirement and postemployment benefits assets		0		0
Deferred income taxes		0		18.9
Deferred charges and other		1.4		4.9
Total Other Noncurrent Assets		1,849.6		1,872
Total Assets		7,929.1		7,873.5
Current Liabilities
Short-term borrowings				0
Short-term borrowings-affiliated		250		99
Accounts payable		0.1		0.1
Accounts payable-affiliated		7.5		10.8
Customer deposits		0		0
Taxes accrued		0		0
Interest accrued		37		9.4
Exchange gas payable		0		0
Deferred revenue		0		0
Accrued capital expenditures		0		0
Accrued compensation and related costs		0		0
Other accruals		0.3		0
Total Current Liabilities		294.9		119.3
Noncurrent Liabilities
Long-term debt		2,727.7		2,725.6
Long-term debt-affiliated		0		0
Deferred income taxes		22.1		0
Accrued liability for postretirement and postemployment benefits		0.2		0.3
Regulatory liabilities		0		0
Asset retirement obligations		0		0
Other noncurrent liabilities		0		15.3
Total Noncurrent Liabilities		2,750		2,741.2
Total Liabilities		3,044.9		2,860.5
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,000 and 399,841,350 shares outstanding, respectively		0.1		4
Additional paid-in capital		4,013.8		4,032.7
(Accumulated deficit) Retained earnings		(56.7)		46.9
Net parent investment		0		0
Accumulated other comprehensive loss		(26.3)		(27)
Total CPG Equity		3,930.9		4,056.6
Noncontrolling Interest		953.3		956.4
Total Equity		4,884.2		5,013
Total Liabilities and Equity		7,929.1		7,873.5
Columbia Energy Group
Current Assets
Cash and cash equivalents		23.1		46.7	4.8		0
Accounts receivable, net		1		5.6
Accounts receivable-affiliated		487.4		85.6
Materials and supplies, at average cost		0		0
Exchange gas receivable		0		0
Deferred property taxes		0		0
Prepayments and other		44.9		10.1
Total Current Assets		556.4		148
Investments
Unconsolidated affiliates		0		0
Consolidated affiliates		7,474.6		7,569.8
Other investments		0.3		0.3
Total Investments		7,474.9		7,570.1
Property, Plant and Equipment
Property, plant and equipment		0		0
Accumulated depreciation and amortization		0		0
Net Property, Plant and Equipment		0		0
Other Noncurrent Assets
Regulatory assets		53.9		35.1
Goodwill		0		0
Notes receivable-affiliated		0		0
Postretirement and postemployment benefits assets		0		0.5
Deferred income taxes		0		0
Deferred charges and other		0		0
Total Other Noncurrent Assets		53.9		35.6
Total Assets		8,085.2		7,753.7
Current Liabilities
Short-term borrowings				0
Short-term borrowings-affiliated		0		0
Accounts payable		0.1		0
Accounts payable-affiliated		15.2		4.8
Customer deposits		0		0
Taxes accrued		0		0
Interest accrued		0		0
Exchange gas payable		0		0
Deferred revenue		0		0
Accrued capital expenditures		0		0
Accrued compensation and related costs		0		0
Other accruals		0.3		0.3
Total Current Liabilities		15.6		5.1
Noncurrent Liabilities
Long-term debt		0		0
Long-term debt-affiliated		1,217.3		1,217.3
Deferred income taxes		1,494.6		1,350.4
Accrued liability for postretirement and postemployment benefits		8.7		8.3
Regulatory liabilities		10.3		10.5
Asset retirement obligations		0		0
Other noncurrent liabilities		1.3		0.2
Total Noncurrent Liabilities		2,732.2		2,586.7
Total Liabilities		2,747.8		2,591.8
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,000 and 399,841,350 shares outstanding, respectively		0		0
Additional paid-in capital		0		0
(Accumulated deficit) Retained earnings		0		0
Net parent investment		4,410.2		4,232.3
Accumulated other comprehensive loss		(26.1)		(26.8)
Total CPG Equity		4,384.1		4,205.5
Noncontrolling Interest		953.3		956.4
Total Equity		5,337.4		5,161.9
Total Liabilities and Equity		8,085.2		7,753.7
Columbia OpCo
Current Assets
Cash and cash equivalents		0		1.9	18.2		0
Accounts receivable, net		0		0
Accounts receivable-affiliated		0		3.4
Materials and supplies, at average cost		0		0
Exchange gas receivable		0		0
Deferred property taxes		0		0
Prepayments and other		0		0
Total Current Assets		0		5.3
Investments
Unconsolidated affiliates		0		0
Consolidated affiliates		5,948		5,608.9
Other investments		0		0
Total Investments		5,948		5,608.9
Property, Plant and Equipment
Property, plant and equipment		0		0
Accumulated depreciation and amortization		0		0
Net Property, Plant and Equipment		0		0
Other Noncurrent Assets
Regulatory assets		0		0
Goodwill		1,975.5		1,975.5
Notes receivable-affiliated		0		0
Postretirement and postemployment benefits assets		0		0
Deferred income taxes		0		0
Deferred charges and other		0		0
Total Other Noncurrent Assets		1,975.5		1,975.5
Total Assets		7,923.5		7,589.7
Current Liabilities
Short-term borrowings				0
Short-term borrowings-affiliated		439.2		0
Accounts payable		0		0
Accounts payable-affiliated		0.7		0
Customer deposits		0		0
Taxes accrued		0		0
Interest accrued		0		0
Exchange gas payable		0		0
Deferred revenue		0		0
Accrued capital expenditures		0		0
Accrued compensation and related costs		0		0
Other accruals		0		0
Total Current Liabilities		439.9		0
Noncurrent Liabilities
Long-term debt		0		0
Long-term debt-affiliated		0		0
Deferred income taxes		0		0
Accrued liability for postretirement and postemployment benefits		0		0
Regulatory liabilities		0		0
Asset retirement obligations		0		0
Other noncurrent liabilities		0		0
Total Noncurrent Liabilities		0		0
Total Liabilities		439.9		0
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,000 and 399,841,350 shares outstanding, respectively		0		0
Additional paid-in capital		0		0
(Accumulated deficit) Retained earnings		0		0
Net parent investment		7,507.4		7,615.4
Accumulated other comprehensive loss		(23.8)		(25.7)
Total CPG Equity		7,483.6		7,589.7
Noncontrolling Interest		0		0
Total Equity		7,483.6		7,589.7
Total Liabilities and Equity		7,923.5		7,589.7
CPG OpCo GP
Current Assets
Cash and cash equivalents		0		0	0		0
Accounts receivable, net		0		0
Accounts receivable-affiliated		0		0
Materials and supplies, at average cost		0		0
Exchange gas receivable		0		0
Deferred property taxes		0		0
Prepayments and other		0		0
Total Current Assets		0		0
Investments
Unconsolidated affiliates		0		0
Consolidated affiliates		0		0
Other investments		0		0
Total Investments		0		0
Property, Plant and Equipment
Property, plant and equipment		0		0
Accumulated depreciation and amortization		0		0
Net Property, Plant and Equipment		0		0
Other Noncurrent Assets
Regulatory assets		0		0
Goodwill		0		0
Notes receivable-affiliated		0		0
Postretirement and postemployment benefits assets		0		0
Deferred income taxes		0		0
Deferred charges and other		0		0
Total Other Noncurrent Assets		0		0
Total Assets		0		0
Current Liabilities
Short-term borrowings				0
Short-term borrowings-affiliated		0		0
Accounts payable		0		0
Accounts payable-affiliated		0		0
Customer deposits		0		0
Taxes accrued		0		0
Interest accrued		0		0
Exchange gas payable		0		0
Deferred revenue		0		0
Accrued capital expenditures		0		0
Accrued compensation and related costs		0		0
Other accruals		0		0
Total Current Liabilities		0		0
Noncurrent Liabilities
Long-term debt		0		0
Long-term debt-affiliated		0		0
Deferred income taxes		0		0
Accrued liability for postretirement and postemployment benefits		0		0
Regulatory liabilities		0		0
Asset retirement obligations		0		0
Other noncurrent liabilities		0		0
Total Noncurrent Liabilities		0		0
Total Liabilities		0		0
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,000 and 399,841,350 shares outstanding, respectively		0		0
Additional paid-in capital		0		0
(Accumulated deficit) Retained earnings		0		0
Net parent investment		0		0
Accumulated other comprehensive loss		0		0
Total CPG Equity		0		0
Noncontrolling Interest		0		0
Total Equity		0		0
Total Liabilities and Equity		0		0
Non-Guarantor Subsidiaries
Current Assets
Cash and cash equivalents		9.6		82.3	$ 40.8		$ 0.5
Accounts receivable, net		158.5		146.8
Accounts receivable-affiliated		181		156.4
Materials and supplies, at average cost		26.4		32.8
Exchange gas receivable		14.3		19
Deferred property taxes		17.7		52
Prepayments and other		43		43.8
Total Current Assets		450.5		533.1
Investments
Unconsolidated affiliates		441.4		438.1
Consolidated affiliates		0		0
Other investments		1.5		1.5
Total Investments		442.9		439.6
Property, Plant and Equipment
Property, plant and equipment		10,200.5		9,052.3
Accumulated depreciation and amortization		(3,092.8)		(2,988.6)
Net Property, Plant and Equipment		7,107.7		6,063.7
Other Noncurrent Assets
Regulatory assets		143.8		142.6
Goodwill		0		0
Notes receivable-affiliated		0		0
Postretirement and postemployment benefits assets		112.1		115.6
Deferred income taxes		70.1		0
Deferred charges and other		9.8		10.6
Total Other Noncurrent Assets		335.8		268.8
Total Assets		8,336.9		7,305.2
Current Liabilities
Short-term borrowings				15
Short-term borrowings-affiliated		739.3		134.3
Accounts payable		83.9		56.7
Accounts payable-affiliated		12.9		11.1
Customer deposits		16.7		17.9
Taxes accrued		165.9		111.7
Interest accrued		0.1		0.1
Exchange gas payable		14.2		18.6
Deferred revenue		5.6		15
Accrued capital expenditures		171.6		100.1
Accrued compensation and related costs		45.1		51.9
Other accruals		100.8		69.7
Total Current Liabilities		1,356.1		602.1
Noncurrent Liabilities
Long-term debt		0		0
Long-term debt-affiliated		630.9		630.9
Deferred income taxes		0		16.6
Accrued liability for postretirement and postemployment benefits		34.9		41.2
Regulatory liabilities		273.9		311.1
Asset retirement obligations		23		25.7
Other noncurrent liabilities		68.8		75.9
Total Noncurrent Liabilities		1,031.5		1,101.4
Total Liabilities		2,387.6		1,703.5
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,000 and 399,841,350 shares outstanding, respectively		0		0
Additional paid-in capital		0		0
(Accumulated deficit) Retained earnings		0		0
Net parent investment		5,977		5,631.3
Accumulated other comprehensive loss		(27.7)		(29.6)
Total CPG Equity		5,949.3		5,601.7
Noncontrolling Interest		0		0
Total Equity		5,949.3		5,601.7
Total Liabilities and Equity		$ 8,336.9		$ 7,305.2
[1]	All amounts are net of tax. Amounts in parentheses indicate debits.

Condensed Consolidating Finan73

Condensed Consolidating Financial Statements (Condensed Consolidating Statements of Operations) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating Revenues
Transportation revenues	$ 270.3	$ 266.2	$ 838.2	$ 752.4
Transportation revenues-affiliated	0	0	0	47.5
Storage revenues	48.9	49.5	147.7	122.3
Storage revenues-affiliated	0	0	0	26.2
Other revenues	7.9	5.2	19.6	28.6
Total Operating Revenues	327.1	320.9	1,005.5	977
Operating Expenses
Operation and maintenance	322.9	186.5	671.9	456
Operation and maintenance-affiliated	0	0	0	52.9
Depreciation and amortization	43.6	35	125.2	101.4
Gain on sale of assets	(9.3)	(39)	(15.3)	(52.6)
Impairment of long-lived assets	19.1	0.6	19.1	2.4
Property and other taxes	19.8	17.3	62.6	55.5
Total Operating Expenses	396.1	200.4	863.5	615.6
Equity Earnings in Unconsolidated Affiliates	16	15.4	48.2	44.5
Equity Earnings in Consolidated Affiliates	0	0	0	0
Operating (Loss) Income	(53)	135.9	190.2	405.9
Other Income (Deductions)
Interest expense	(31.4)	(29.4)	(91.4)	(42.3)
Interest expense-affiliated	(0.5)	0	(0.5)	(29.3)
Other, net	13.7	6.7	30.5	16.6
Total Other Deductions, net	(18.2)	(22.7)	(61.4)	(55)
Income from Continuing Operations before Income Taxes	(71.2)	113.2	128.8	350.9
Income Taxes	(21.6)	38.3	43.2	118.8
(Loss) Income from Continuing Operations	(49.6)	74.9	85.6	232.1
(Loss) Income from Discontinued Operations-net of taxes	0	(0.1)	0.2	(0.4)
Net (Loss) Income	(49.6)	74.8	85.8	231.7
Less: Net income attributable to noncontrolling interest	2.9	11.8	27.2	27.9
Net income attributable to CPG	(52.5)	63	58.6	203.8
Consolidating adjustments and eliminations
Operating Revenues
Transportation revenues	0	0	0	0
Transportation revenues-affiliated				0
Storage revenues	0	0	0	0
Storage revenues-affiliated				0
Other revenues	0	0	0	0
Total Operating Revenues	0	0	0	0
Operating Expenses
Operation and maintenance	0	0	(0.2)	0
Operation and maintenance-affiliated	(1.1)	(1.5)	(1.6)	(1.5)
Depreciation and amortization	0	0	0	0
Gain on sale of assets	0	0	0	0
Impairment of long-lived assets	0	0	0	0
Property and other taxes	0	0	0	0
Total Operating Expenses	(1.1)	(1.5)	(1.8)	(1.5)
Equity Earnings in Unconsolidated Affiliates	0	0	0	0
Equity Earnings in Consolidated Affiliates	(53.4)	(376.2)	(870.4)	(1,015.1)
Operating (Loss) Income	(52.3)	(374.7)	(868.6)	(1,013.6)
Other Income (Deductions)
Interest expense	1.8	1.6	3.7	1.6
Interest expense-affiliated	20	19.6	56.7	26.4
Other, net	(21.8)	(21.2)	(60.4)	(28)
Total Other Deductions, net	0	0	0	0
Income from Continuing Operations before Income Taxes	(52.3)	(374.7)	(868.6)	(1,013.6)
Income Taxes	2	0	2	(1.6)
(Loss) Income from Continuing Operations		(374.7)	(870.6)	(1,012)
(Loss) Income from Discontinued Operations-net of taxes		0.1	(0.2)	0.4
Net (Loss) Income	(54.3)	(374.6)	(870.8)	(1,011.6)
Less: Net income attributable to noncontrolling interest	(2.9)	(11.8)	(27.2)	(27.9)
Net income attributable to CPG	(51.4)	(362.8)	(843.6)	(983.7)
Columbia Pipeline Group
Operating Revenues
Transportation revenues	0	0	0	0
Transportation revenues-affiliated				0
Storage revenues	0	0	0	0
Storage revenues-affiliated				0
Other revenues	0	0	0	0
Total Operating Revenues	0	0	0	0
Operating Expenses
Operation and maintenance	67.2	6.3	135.4	6.6
Operation and maintenance-affiliated	1.1	1.5	1.6	1.5
Depreciation and amortization	0	0	0	0
Gain on sale of assets	0	0	0	0
Impairment of long-lived assets	0	0	0	0
Property and other taxes	0	0	0.1	0
Total Operating Expenses	68.3	7.8	137.1	8.1
Equity Earnings in Unconsolidated Affiliates	0	0	0	0
Equity Earnings in Consolidated Affiliates	9.8	87.7	202.4	249.4
Operating (Loss) Income	(58.5)	79.9	65.3	241.3
Other Income (Deductions)
Interest expense	(33)	(29.9)	(92.2)	(42.8)
Interest expense-affiliated	(0.5)	(1.6)	(0.5)	(1.9)
Other, net	20.3	19	59.3	26.1
Total Other Deductions, net	(13.2)	(12.5)	(33.4)	(18.6)
Income from Continuing Operations before Income Taxes	(71.7)	67.4	31.9	222.7
Income Taxes	(22.1)	(7.5)	(53.7)	(9.4)
(Loss) Income from Continuing Operations		74.9	85.6	232.1
(Loss) Income from Discontinued Operations-net of taxes		(0.1)	0.2	(0.4)
Net (Loss) Income	(49.6)	74.8	85.8	231.7
Less: Net income attributable to noncontrolling interest	2.9	11.8	27.2	27.9
Net income attributable to CPG	(52.5)	63	58.6	203.8
Columbia Energy Group
Operating Revenues
Transportation revenues	0	0	0	0
Transportation revenues-affiliated				0
Storage revenues	0	0	0	0
Storage revenues-affiliated				0
Other revenues	0	0	0	0
Total Operating Revenues	0	0	0	0
Operating Expenses
Operation and maintenance	0	(0.4)	(0.2)	(1.2)
Operation and maintenance-affiliated	0	0	0	0.3
Depreciation and amortization	0.2	0	0.6	0
Gain on sale of assets	0	0	0	0
Impairment of long-lived assets	0	0	0	1.8
Property and other taxes	0	0	0	0
Total Operating Expenses	0.2	(0.4)	0.4	0.9
Equity Earnings in Unconsolidated Affiliates	0	0	0	0
Equity Earnings in Consolidated Affiliates	21	144.9	330.6	383.2
Operating (Loss) Income	20.8	145.3	330.2	382.3
Other Income (Deductions)
Interest expense	0	0	0	0
Interest expense-affiliated	(11.3)	(11.4)	(33.7)	(29.5)
Other, net	1.4	0.1	2.2	0.3
Total Other Deductions, net	(9.9)	(11.3)	(31.5)	(29.2)
Income from Continuing Operations before Income Taxes	10.9	134	298.7	353.1
Income Taxes	(1.2)	45.8	93.9	103.6
(Loss) Income from Continuing Operations		88.2	204.8	249.5
(Loss) Income from Discontinued Operations-net of taxes		(0.1)	0.2	(0.4)
Net (Loss) Income	12.1	88.1	205	249.1
Less: Net income attributable to noncontrolling interest	2.9	11.8	27.2	27.9
Net income attributable to CPG	9.2	76.3	177.8	221.2
Columbia OpCo
Operating Revenues
Transportation revenues	0	0	0	0
Transportation revenues-affiliated				0
Storage revenues	0	0	0	0
Storage revenues-affiliated				0
Other revenues	0	0	0	0
Total Operating Revenues	0	0	0	0
Operating Expenses
Operation and maintenance	0	0	0	0
Operation and maintenance-affiliated	0	0	0	0
Depreciation and amortization	0	0	0	0
Gain on sale of assets	0	0	0	0
Impairment of long-lived assets	0	0	0	0
Property and other taxes	0.1	0	0.1	0
Total Operating Expenses	0.1	0	0.1	0
Equity Earnings in Unconsolidated Affiliates	0	0	0	0
Equity Earnings in Consolidated Affiliates	22.6	143.6	337.4	382.5
Operating (Loss) Income	22.5	143.6	337.3	382.5
Other Income (Deductions)
Interest expense	0	0	0	0
Interest expense-affiliated	(1.1)	0	(1.5)	0
Other, net	0	1.8	0	3.3
Total Other Deductions, net	(1.1)	1.8	(1.5)	3.3
Income from Continuing Operations before Income Taxes	21.4	145.4	335.8	385.8
Income Taxes	0	0	0	0
(Loss) Income from Continuing Operations		145.4	335.8	385.8
(Loss) Income from Discontinued Operations-net of taxes		0	0	0
Net (Loss) Income	21.4	145.4	335.8	385.8
Less: Net income attributable to noncontrolling interest	0	0	0	0
Net income attributable to CPG	21.4	145.4	335.8	385.8
CPG OpCo GP
Operating Revenues
Transportation revenues	0	0	0	0
Transportation revenues-affiliated				0
Storage revenues	0	0	0	0
Storage revenues-affiliated				0
Other revenues	0	0	0	0
Total Operating Revenues	0	0	0	0
Operating Expenses
Operation and maintenance	0	0	0	0
Operation and maintenance-affiliated	0	0	0	0
Depreciation and amortization	0	0	0	0
Gain on sale of assets	0	0	0	0
Impairment of long-lived assets	0	0	0	0
Property and other taxes	0	0	0	0
Total Operating Expenses	0	0	0	0
Equity Earnings in Unconsolidated Affiliates	0	0	0	0
Equity Earnings in Consolidated Affiliates	0	0	0	0
Operating (Loss) Income	0	0	0	0
Other Income (Deductions)
Interest expense	0	0	0	0
Interest expense-affiliated	0	0	0	0
Other, net	0	0	0	0
Total Other Deductions, net	0	0	0	0
Income from Continuing Operations before Income Taxes	0	0	0	0
Income Taxes	0	0	0	0
(Loss) Income from Continuing Operations		0	0	0
(Loss) Income from Discontinued Operations-net of taxes		0	0	0
Net (Loss) Income	0	0	0	0
Less: Net income attributable to noncontrolling interest	0	0	0	0
Net income attributable to CPG	0	0	0	0
Non-Guarantor Subsidiaries
Operating Revenues
Transportation revenues	270.3	266.2	838.2	752.4
Transportation revenues-affiliated				47.5
Storage revenues	48.9	49.5	147.7	122.3
Storage revenues-affiliated				26.2
Other revenues	7.9	5.2	19.6	28.6
Total Operating Revenues	327.1	320.9	1,005.5	977
Operating Expenses
Operation and maintenance	255.7	180.6	536.9	450.6
Operation and maintenance-affiliated	0	0	0	52.6
Depreciation and amortization	43.4	35	124.6	101.4
Gain on sale of assets	(9.3)	(39)	(15.3)	(52.6)
Impairment of long-lived assets	19.1	0.6	19.1	0.6
Property and other taxes	19.7	17.3	62.4	55.5
Total Operating Expenses	328.6	194.5	727.7	608.1
Equity Earnings in Unconsolidated Affiliates	16	15.4	48.2	44.5
Equity Earnings in Consolidated Affiliates	0	0	0	0
Operating (Loss) Income	14.5	141.8	326	413.4
Other Income (Deductions)
Interest expense	(0.2)	(1.1)	(2.9)	(1.1)
Interest expense-affiliated	(7.6)	(6.6)	(21.5)	(24.3)
Other, net	13.8	7	29.4	14.9
Total Other Deductions, net	6	(0.7)	5	(10.5)
Income from Continuing Operations before Income Taxes	20.5	141.1	331	402.9
Income Taxes	(0.3)	0	1	26.2
(Loss) Income from Continuing Operations		141.1	330	376.7
(Loss) Income from Discontinued Operations-net of taxes		0	0	0
Net (Loss) Income	20.8	141.1	330	376.7
Less: Net income attributable to noncontrolling interest	0	0	0	0
Net income attributable to CPG	$ 20.8	$ 141.1	$ 330	$ 376.7

Condensed Consolidating Finan74

Condensed Consolidating Financial Statements (Condensed Statements of Comprehensive Income) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Condensed Statement of Income Captions [Line Items]
Net Income		$ (49.6)	$ 74.8	$ 85.8	$ 231.7
Net unrealized gain (loss) on cash flow hedges	[1]	0.3	(0.7)	1	(0.2)
Unrecognized pension and OPEB benefit (cost)	[2],[3]	(0.4)	(0.1)	(0.2)	7.2
Total other comprehensive (loss) income	[4]	(0.1)	(0.8)	0.8	7
Total comprehensive (loss) income		(49.7)	74	86.6	238.7
Less: Comprehensive Income-noncontrolling interest		2.9	11.8	27.3	27.9
Comprehensive (Loss) Income-controlling interests		(52.6)	62.2	59.3	210.8
Consolidating adjustments and eliminations
Condensed Statement of Income Captions [Line Items]
Net Income		(54.3)	(374.6)	(870.8)	(1,011.6)
Net unrealized gain (loss) on cash flow hedges		(0.3)	0.7	(1)	0.2
Unrecognized pension and OPEB benefit (cost)		0.4	0.1	0.2	(7.2)
Total other comprehensive (loss) income		0.1	0.8	(0.8)	(7)
Total comprehensive (loss) income		(54.2)	(373.8)	(871.6)	(1,018.6)
Less: Comprehensive Income-noncontrolling interest		(2.9)	(11.8)	(27.3)	(27.9)
Comprehensive (Loss) Income-controlling interests		(51.3)	(362)	(844.3)	(990.7)
Columbia Pipeline Group
Condensed Statement of Income Captions [Line Items]
Net Income		(49.6)	74.8	85.8	231.7
Net unrealized gain (loss) on cash flow hedges		0.3	(0.7)	1	(0.2)
Unrecognized pension and OPEB benefit (cost)		(0.4)	(0.1)	(0.2)	7.2
Total other comprehensive (loss) income		(0.1)	(0.8)	0.8	7
Total comprehensive (loss) income		(49.7)	74	86.6	238.7
Less: Comprehensive Income-noncontrolling interest		2.9	11.8	27.3	27.9
Comprehensive (Loss) Income-controlling interests		(52.6)	62.2	59.3	210.8
Columbia Energy Group
Condensed Statement of Income Captions [Line Items]
Net Income		12.1	88.1	205	249.1
Net unrealized gain (loss) on cash flow hedges		(0.3)	(1.2)	(0.6)	(1.5)
Unrecognized pension and OPEB benefit (cost)		(0.5)	0.1	(0.3)	7.4
Total other comprehensive (loss) income		(0.8)	(1.1)	(0.9)	5.9
Total comprehensive (loss) income		11.3	87	204.1	255
Less: Comprehensive Income-noncontrolling interest		2.9	11.8	27.3	27.9
Comprehensive (Loss) Income-controlling interests		8.4	75.2	176.8	227.1
Columbia OpCo
Condensed Statement of Income Captions [Line Items]
Net Income		21.4	145.4	335.8	385.8
Net unrealized gain (loss) on cash flow hedges		0	0	0	0
Unrecognized pension and OPEB benefit (cost)		0	0	0	0
Total other comprehensive (loss) income		0	0	0	0
Total comprehensive (loss) income		21.4	145.4	335.8	385.8
Less: Comprehensive Income-noncontrolling interest		0	0	0	0
Comprehensive (Loss) Income-controlling interests		21.4	145.4	335.8	385.8
CPG OpCo GP
Condensed Statement of Income Captions [Line Items]
Net Income		0	0	0	0
Net unrealized gain (loss) on cash flow hedges		0	0	0	0
Unrecognized pension and OPEB benefit (cost)		0	0	0	0
Total other comprehensive (loss) income		0	0	0	0
Total comprehensive (loss) income		0	0	0	0
Less: Comprehensive Income-noncontrolling interest		0	0	0	0
Comprehensive (Loss) Income-controlling interests		0	0	0	0
Non-Guarantor Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net Income		20.8	141.1	330	376.7
Net unrealized gain (loss) on cash flow hedges		0.6	0.5	1.6	1.3
Unrecognized pension and OPEB benefit (cost)		0.1	(0.2)	0.1	(0.2)
Total other comprehensive (loss) income		0.7	0.3	1.7	1.1
Total comprehensive (loss) income		21.5	141.4	331.7	377.8
Less: Comprehensive Income-noncontrolling interest		0	0	0	0
Comprehensive (Loss) Income-controlling interests		$ 21.5	$ 141.4	$ 331.7	$ 377.8
[1]	Net unrealized gain (loss) on derivatives qualifying as cash flow hedges, net of $0.3 million and $1.1 million tax expense for the three months ended September 30, 2016 and 2015, respectively, and $0.6 million and $1.4 million tax expense for the nine months ended September 30, 2016 and 2015, respectively.
[2]	Unrecognized pension and OPEB benefit (cost), net of $0.2 million and $0.1 million tax benefit for the three months ended September 30, 2016 and 2015, respectively, and $0.1 million tax benefit for the nine months ended September 30, 2016 and 2015.
[3]	Unrecognized pension and OPEB benefits are primarily related to pension and OPEB remeasurements recorded during 2016 and 2015.
[4]	All amounts are net of tax. Amounts in parentheses indicate debits.

Condensed Consolidating Finan75

Condensed Consolidating Financial Statements (Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	$ 253	$ 414.2
Investing Activities
Capital expenditures	(1,095.8)	(833)
Insurance recoveries	0	2.1
Change in short-term lendings-affiliated	0	145.5
Proceeds from disposition of assets	9.9	53.3
Contributions to equity investees	(6.2)	(1.4)
Distributions from equity investees	1.6	15.1
Other investing activities	3.8	(24.2)
Net Cash Flows used for Investing Activities	(1,086.7)	(642.6)
Financing Activities
Change in short-term borrowings	(15)	245
Change in short-term borrowings-affiliated	250	(252.5)
Issuance of long-term debt	0	2,745.9
Payments of capital lease obligations and other debt related costs	(2.5)	(23.6)
Issuance of long-term debt-affiliated	0	1,217.3
Payments of long-term debt-affiliated, including current portion	0	(2,806)
Proceeds from the issuance of common units, net of offering costs	0	1,168.4
Contribution of capital from parent	0.1	0
Distribution of IPO proceeds to NiSource	0	(500)
Distribution to NiSource	0	1,450
Quarterly distributions to unitholders	0	0
Distribution to noncontrolling interest in Columbia OpCo	0	0
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries		0
Distribution to noncontrolling interest	(30.4)	(13.9)
Acquisition of treasury stock	(6.2)	0
Dividends paid - common stock	(105.1)	(39.7)
Dividends paid to TransCanada	(55.5)	0
Transfer from parent	0	0.8
Net Cash Flows from Financing Activities	35.4	291.7
Change in cash and cash equivalents	(798.3)	63.3
Cash and cash equivalents at beginning of period	930.9	0.5
Cash and Cash Equivalents at End of Period	132.6	63.8
Consolidating adjustments and eliminations
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	(470.1)	(12.1)
Investing Activities
Capital expenditures	0	3.8
Insurance recoveries		0
Change in short-term lendings-affiliated	945.3	424.5
Proceeds from disposition of assets	0	(3.8)
Contributions to equity investees	0	1,663.5
Distributions from equity investees	0	0
Other investing activities	0	0
Net Cash Flows used for Investing Activities	945.3	2,088
Financing Activities
Change in short-term borrowings	0	0
Change in short-term borrowings-affiliated	(945.3)	(424.5)
Issuance of long-term debt		0
Payments of capital lease obligations and other debt related costs	0	0
Issuance of long-term debt-affiliated		0
Payments of long-term debt-affiliated, including current portion		0
Proceeds from the issuance of common units, net of offering costs		0
Contribution of capital from parent	0	(1,663.5)
Distribution of IPO proceeds to NiSource		0
Distribution to NiSource		0
Quarterly distributions to unitholders	56.9	26
Distribution to noncontrolling interest in Columbia OpCo	443.6	69.9
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries		(69.9)
Distribution to noncontrolling interest	(30.4)	(13.9)
Acquisition of treasury stock	0
Dividends paid - common stock	0	0
Dividends paid to TransCanada	0
Transfer from parent		0
Net Cash Flows from Financing Activities	(475.2)	(2,075.9)
Change in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and Cash Equivalents at End of Period	0	0
Columbia Pipeline Group
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	(174.7)	6.2
Investing Activities
Capital expenditures	0	0
Insurance recoveries		0
Change in short-term lendings-affiliated	(519.4)	0
Proceeds from disposition of assets	0	0
Contributions to equity investees	0	0
Distributions from equity investees	0	0
Other investing activities	10.3	(5.2)
Net Cash Flows used for Investing Activities	(509.1)	(5.2)
Financing Activities
Change in short-term borrowings	0	225
Change in short-term borrowings-affiliated	151	388.8
Issuance of long-term debt		2,745.9
Payments of capital lease obligations and other debt related costs	(0.6)	(23.6)
Issuance of long-term debt-affiliated		0
Payments of long-term debt-affiliated, including current portion		(1,848.2)
Proceeds from the issuance of common units, net of offering costs		0
Contribution of capital from parent	0.1	0
Distribution of IPO proceeds to NiSource		0
Distribution to NiSource		1,450
Quarterly distributions to unitholders	0	0
Distribution to noncontrolling interest in Columbia OpCo	0	0
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries		0
Distribution to noncontrolling interest	0	0
Acquisition of treasury stock	(6.2)
Dividends paid - common stock	(105.1)	(39.7)
Dividends paid to TransCanada	(55.5)
Transfer from parent		0.8
Net Cash Flows from Financing Activities	(16.3)	(1)
Change in cash and cash equivalents	(700.1)	0
Cash and cash equivalents at beginning of period	800	0
Cash and Cash Equivalents at End of Period	99.9	0
Columbia Energy Group
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	376.9	(24.5)
Investing Activities
Capital expenditures	0	(3.8)
Insurance recoveries		0
Change in short-term lendings-affiliated	(400.5)	(33.2)
Proceeds from disposition of assets	0	2.1
Contributions to equity investees	0	(1,217.3)
Distributions from equity investees	0	0
Other investing activities	0	0
Net Cash Flows used for Investing Activities	(400.5)	(1,252.2)
Financing Activities
Change in short-term borrowings	0	0
Change in short-term borrowings-affiliated	0	(5.1)
Issuance of long-term debt		0
Payments of capital lease obligations and other debt related costs	0	0
Issuance of long-term debt-affiliated		1,217.3
Payments of long-term debt-affiliated, including current portion		0
Proceeds from the issuance of common units, net of offering costs		0
Contribution of capital from parent	0	0
Distribution of IPO proceeds to NiSource		0
Distribution to NiSource		0
Quarterly distributions to unitholders	0	0
Distribution to noncontrolling interest in Columbia OpCo	0	0
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries		69.9
Distribution to noncontrolling interest	0	0
Acquisition of treasury stock	0
Dividends paid - common stock	0	0
Dividends paid to TransCanada	0
Transfer from parent		(0.6)
Net Cash Flows from Financing Activities	0	1,281.5
Change in cash and cash equivalents	(23.6)	4.8
Cash and cash equivalents at beginning of period	46.7	0
Cash and Cash Equivalents at End of Period	23.1	4.8
Columbia OpCo
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	(0.8)	4.1
Investing Activities
Capital expenditures	0	0
Insurance recoveries		0
Change in short-term lendings-affiliated	3.3	(126.8)
Proceeds from disposition of assets	0	0
Contributions to equity investees	0	(446.2)
Distributions from equity investees	0	0
Other investing activities	0	0
Net Cash Flows used for Investing Activities	3.3	(573)
Financing Activities
Change in short-term borrowings	0	0
Change in short-term borrowings-affiliated	439.2	0
Issuance of long-term debt		0
Payments of capital lease obligations and other debt related costs	0	0
Issuance of long-term debt-affiliated		0
Payments of long-term debt-affiliated, including current portion		0
Proceeds from the issuance of common units, net of offering costs		1,170
Contribution of capital from parent	0	0
Distribution of IPO proceeds to NiSource		(500)
Distribution to NiSource		0
Quarterly distributions to unitholders	0	0
Distribution to noncontrolling interest in Columbia OpCo	(443.6)	(69.9)
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries		0
Distribution to noncontrolling interest	0	0
Acquisition of treasury stock	0
Dividends paid - common stock	0	0
Dividends paid to TransCanada	0
Transfer from parent		(13)
Net Cash Flows from Financing Activities	(4.4)	587.1
Change in cash and cash equivalents	(1.9)	18.2
Cash and cash equivalents at beginning of period	1.9	0
Cash and Cash Equivalents at End of Period	0	18.2
CPG OpCo GP
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	0	0
Investing Activities
Capital expenditures	0	0
Insurance recoveries		0
Change in short-term lendings-affiliated	0	0
Proceeds from disposition of assets	0	0
Contributions to equity investees	0	0
Distributions from equity investees	0	0
Other investing activities	0	0
Net Cash Flows used for Investing Activities	0	0
Financing Activities
Change in short-term borrowings	0	0
Change in short-term borrowings-affiliated	0	0
Issuance of long-term debt		0
Payments of capital lease obligations and other debt related costs	0	0
Issuance of long-term debt-affiliated		0
Payments of long-term debt-affiliated, including current portion		0
Proceeds from the issuance of common units, net of offering costs		0
Contribution of capital from parent	0	0
Distribution of IPO proceeds to NiSource		0
Distribution to NiSource		0
Quarterly distributions to unitholders	0	0
Distribution to noncontrolling interest in Columbia OpCo	0	0
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries		0
Distribution to noncontrolling interest	0	0
Acquisition of treasury stock	0
Dividends paid - common stock	0	0
Dividends paid to TransCanada	0
Transfer from parent		0
Net Cash Flows from Financing Activities	0	0
Change in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and Cash Equivalents at End of Period	0	0
Non-Guarantor Subsidiaries
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Cash Provided by (Used in) Operating Activities	521.7	440.5
Investing Activities
Capital expenditures	(1,095.8)	(833)
Insurance recoveries		2.1
Change in short-term lendings-affiliated	(28.7)	(119)
Proceeds from disposition of assets	9.9	55
Contributions to equity investees	(6.2)	(1.4)
Distributions from equity investees	1.6	15.1
Other investing activities	(6.5)	(19)
Net Cash Flows used for Investing Activities	(1,125.7)	(900.2)
Financing Activities
Change in short-term borrowings	(15)	20
Change in short-term borrowings-affiliated	605.1	(211.7)
Issuance of long-term debt		0
Payments of capital lease obligations and other debt related costs	(1.9)	0
Issuance of long-term debt-affiliated		0
Payments of long-term debt-affiliated, including current portion		(957.8)
Proceeds from the issuance of common units, net of offering costs		(1.6)
Contribution of capital from parent	0	1,663.5
Distribution of IPO proceeds to NiSource		0
Distribution to NiSource		0
Quarterly distributions to unitholders	(56.9)	(26)
Distribution to noncontrolling interest in Columbia OpCo	0	0
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries		0
Distribution to noncontrolling interest	0	0
Acquisition of treasury stock	0
Dividends paid - common stock	0	0
Dividends paid to TransCanada	0
Transfer from parent		13.6
Net Cash Flows from Financing Activities	531.3	500
Change in cash and cash equivalents	(72.7)	40.3
Cash and cash equivalents at beginning of period	82.3	0.5
Cash and Cash Equivalents at End of Period	$ 9.6	$ 40.8

Subsequent Event (Narrative) (D

Subsequent Event (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	Nov. 01, 2016	Jul. 01, 2016	Sep. 30, 2016
Subsequent Event [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest			100.00%
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest		46.50%
Business Acquisition, Share Price		$ 25.50
Subsequent Event
Subsequent Event [Line Items]
Business Acquisition, Date of Acquisition Agreement	Nov. 1, 2016
Business Acquisition, Share Price	$ 17
Daily Distribution Rate	0.00217
Distribution to Limited Partner, Minimum Quarterly Distribution, Per Unit	$ 0.1975
Number of days in quarter	91
Distribution Made to Limited Partner, Distributions Declared, Per Unit	$ 0.1975
Columbia Energy Group | Subordinated Units
Subsequent Event [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest			100.00%
Limited Partners' Capital Account, Units Outstanding			46,811,398
Columbia Energy Group | Subordinated Units
Subsequent Event [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest			46.50%
Maximum | Subsequent Event
Subsequent Event [Line Items]
Termination Payment	$ 10