Columbia Pipeline (CPGX) 10-K 17 Feb 17 2016 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Feb. 16, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
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 Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 0
Entity Common Stock, Shares Outstanding		0

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current Assets
Cash and cash equivalents		$ 79.9	$ 930.9	$ 0.5	$ 0.4
Accounts receivable (less reserve of $0.3 and $0.6, respectively)		194.2	152.4
Accounts receivable-affiliated		55.8	0
Materials and supplies, at average cost		26	32.8
Exchange gas receivable		27.7	19
Deferred property taxes		61.2	52
Prepayments and other		28.9	48.5
Total Current Assets		473.7	1,235.6
Investments
Unconsolidated affiliates		446.7	438.1
Other investments		0.8	13.8
Total Investments		447.5	451.9
Property, Plant and Equipment
Property, plant and equipment		10,461.2	9,052.3
Accumulated depreciation and amortization		(3,126.2)	(2,988.6)
Net Property, Plant and Equipment		7,335	6,063.7
Other Noncurrent Assets
Regulatory assets		172.9	177.7
Goodwill		1,975.5	1,975.5
Postretirement and postemployment benefits assets		121.8	115.7
Deferred charges and other		11.3	15.5
Total Other Noncurrent Assets		2,281.5	2,284.4
Total Assets		10,537.7	10,035.6
Current Liabilities
Short-term borrowings		0	15
Accounts payable		70.4	56.8
Accounts payable-affiliated		4	0
Customer deposits		17.3	17.9
Taxes accrued		116.9	106
Interest accrued		9.4	9.5
Exchange gas payable		27.2	18.6
Deferred revenue		3.9	15
Accrued capital expenditures		111.4	100.1
Accrued compensation and related costs		62.3	51.9
Other accruals		110.1	70
Total Current Liabilities		532.9	460.8
Noncurrent Liabilities
Long-term debt		2,728.6	2,725.6
Deferred income taxes		1,500.4	1,348.1
Accrued liability for postretirement and postemployment benefits		32.2	49.4
Regulatory liabilities		273.6	321.6
Asset retirement obligations		20.8	25.7	23.2
Other noncurrent liabilities		59.8	91.4
Total Noncurrent Liabilities		4,615.4	4,561.8
Total Liabilities		5,148.3	5,022.6
Temporary Equity
Redeemable noncontrolling interest		952.9	0
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,150 and 399,841,350 shares outstanding, respectively		0.1	4
Additional paid-in capital		4,513.8	4,032.7
(Accumulated deficit) Retained earnings		(53.5)	46.9
Accumulated other comprehensive loss	[1]	(23.9)	(27)	(34.5)
Total CPG Equity		4,436.5	4,056.6	$ 4,176.3
Noncontrolling Interest		0	956.4
Total Equity		4,436.5	5,013
Total Liabilities, Temporary Equity and Equity		$ 10,537.7	$ 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	Dec. 31, 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	10,000,150	399,841,350

Statements of Consolidated and

Statements of Consolidated and Combined Operations - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Revenues
Transportation revenues		$ 1,155.1	$ 1,054.4	$ 990.8
Transportation revenues-affiliated		0	47.5	95.7
Storage revenues		196.5	171.4	144
Storage revenues-affiliated		0	26.2	53.2
Other revenues		30.4	35.4	64.3
Total Operating Revenues		1,382	1,334.9	1,348
Operating Expenses
Operation and maintenance		863.2	652.1	628.4
Operation and maintenance-affiliated		0	52.9	123.2
Depreciation and amortization		172.8	139.9	118.8
Gain on sale of assets		(16.6)	(55.3)	(34.5)
Impairment of long-lived assets		26.1	2.4	0
Property and other taxes		83.2	75.3	67.1
Total Operating Expenses		1,128.7	867.3	903
Equity Earnings in Unconsolidated Affiliates		64.3	60.5	46.6
Operating Income		317.6	528.1	491.6
Other Income (Deductions)
Interest expense	[1]	(119.1)	(67.6)	0
Interest expense-affiliated		(2.1)	(29.3)	(62)
Other, net		35.1	29.3	8.8
Total Other Deductions, net		(86.1)	(67.6)	(53.2)
Income from Continuing Operations before Income Taxes		231.5	460.5	438.4
Income Taxes		77.8	153	169.7
Income from Continuing Operations		153.7	307.5	268.7
Income (Loss) from Discontinued Operations-net of taxes		0.2	(0.4)	(0.6)
Net Income		153.9	307.1	268.1
Less: Net income attributable to noncontrolling interest		37.1	39.9
Net Income Attributable to CPG		116.8	267.2	268.1
Amounts Attributable to CPG
Income from Continuing Operations		116.6	267.6	268.7
Income (Loss) from Discontinued Operations-net of taxes		0.2	(0.4)	(0.6)
Net Income Attributable to CPG		$ 116.8	$ 267.2	$ 268.1
[1]	Refer to Note 4, "Transactions with Affiliates" for a discussion of interest expense-affiliated for the year ended December 31, 2016, 2015 and 2014.

Statements of Consolidated and5

Statements of Consolidated and Combined Comprehensive Income - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income		$ 153.9		$ 307.1		$ 268.1
Net unrealized gain on cash flow hedges	[1]	1.3		0.2		1
Unrecognized pension and OPEB benefit (cost)	[2]	2	[3]	5.2	[3]	(9.7)
Total other comprehensive income (loss)	[4]	3.3		5.4		(8.7)
Total Comprehensive Income		157.2		312.5		259.4
Less: Comprehensive Income-noncontrolling interest		37.3		40		0
Comprehensive Income-controlling interests		$ 119.9		$ 272.5		$ 259.4
[1]	Net unrealized gain on derivatives qualifying as cash flow hedges, net of $0.7 million, $0.2 million and $0.7 million tax expense in 2016, 2015 and 2014, respectively.
[2]	Unrecognized pension and OPEB benefit (cost), net of $1.3 million tax expense, $1.2 million tax benefit, and $6.1 million tax benefit in 2016, 2015 and 2014, respectively.
[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 and6

Statements of Consolidated and Combined Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	$ 0.7	$ 0.2	$ 0.7
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax	$ 1.3	$ (1.2)	$ (6.1)

Statements of Consolidated and7

Statements of Consolidated and Combined Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Cash Flows [Abstract]
Net Income	$ 153.9	$ 307.1	$ 268.1
Adjustments to Reconcile Net Income to Net Cash from Continuing Operations:
Depreciation and amortization	172.8	139.9	118.8
Deferred income taxes and investment tax credits	129.4	131.9	142.6
Deferred revenue	(3.2)	4.2	1.6
Equity-based compensation expense and profit sharing contribution	1.7	9.4	6.3
Gain on sale of assets	(16.6)	(55.3)	(34.5)
Impairment of long-lived assets	26.1	2.4	0
Equity earnings in unconsolidated affiliates	(64.3)	(60.5)	(46.6)
(Income) loss from discontinued operations-net of taxes	(0.2)	0.4	0.6
Amortization of debt related costs	10.2	3.1	0
AFUDC equity	(34.9)	(28.3)	(11)
Distributions of earnings received from equity investees	61.5	57.2	37.8
Accounts receivable	(39.2)	(17.4)	(20.3)
Accounts receivable-affiliated	(55.8)	34.7	(3.6)
Accounts payable	16	(5)	2.8
Accounts payable-affiliated	3.4	(53.6)	12.4
Customer deposits	(0.6)	(22.9)	77.5
Taxes accrued	8.8	8.2	12
Interest accrued	0.1	9.4	0
Exchange gas receivable/payable	(0.2)	(0.3)	1.1
Other accruals	1.7	50.2	0.9
Prepayments and other current assets	16.2	(27.1)	(4.4)
Regulatory assets/liabilities	11.2	20.2	9
Postretirement and postemployment benefits	(14.5)	(4.4)	(1.3)
Deferred charges and other noncurrent assets	(8)	(16.3)	(4.3)
Other noncurrent liabilities	(15.6)	6.5	0.7
Net Operating Activities from Continuing Operations	359.9	493.7	566.2
Net Operating Activities from (used for) Discontinued Operations	(0.3)	0.2	1.4
Net Cash Provided by (Used in) Operating Activities	360.2	493.5	564.8
Investing Activities
Capital expenditures	(1,438.1)	(1,181)	(747.2)
Insurance recoveries	3	2.1	11.3
Changes in short-term lendings-affiliated	0	145.5	(57.2)
Proceeds from disposition of assets	10.4	77.6	9.3
Contributions to equity investees	(6.2)	(1.4)	(69.2)
Distributions from equity investees	2.2	16	0
Other investing activities	0.6	(27.4)	(7.1)
Net Cash Flows used for Investing Activities	(1,428.1)	(968.6)	(860.1)
Financing Activities
Change in short-term borrowings	(15)	15	0
Change in short-term borrowings-affiliated	500	(252.5)	(467.1)
Repayment of short-term debt to related parties	(500)	0	0
Issuance of long-term debt	0	2,745.9	0
Payment of capital lease obligations and other debt related costs	(5.4)	(23.6)	(6.4)
Issuance of long-term debt-affiliated	0	1,217.3	768.9
Payments of long-term debt-affiliated, including current portion	0	(2,807.8)	0
Proceeds from issuance of common units, net of offering costs	0	1,168.4	0
Issuance of common stock, net of offering costs	0	1,394.7	0
Issuance of common stock, net of offering costs	500.1	0	0
Distribution of IPO proceeds to NiSource	0	(500)	0
Distribution to NiSource	0	(1,450)	0
Distribution to noncontrolling interest	(41)	(23.2)	0
Acquisition of treasury stock	(6.2)	0	0
Dividends paid - common stock	(105.1)	(79.5)	0
Dividends paid to TransCanada	(110.5)	0	0
Transfer from NiSource	0	0.8	0
Net Cash Flows from Financing Activities	216.9	1,405.5	295.4
Change in cash and cash equivalents	(851)	930.4	0.1
Cash and cash equivalents at beginning of period	930.9	0.5	0.4
Cash and cash equivalents at end of period	$ 79.9	$ 930.9	$ 0.5

Statements of Consolidated and8

Statements of Consolidated and Combined Equity - USD ($) shares in Millions, $ in Millions		Total		Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Net Parent Investment	Accumulated Other Comprehensive Loss	Noncontrolling Interest
Beginning Balance (Predecessor) at Dec. 31, 2013		$ 3,915.6		$ 0	$ 0	$ 0	$ 0	$ 3,941.4	$ (25.8)	$ 0
Net Income (Loss) Attributable to Parent		268.1		0	0	0	0	268.1	0
Income (Loss) Attributable to Noncontrolling Interest										0
Other Comprehensive Income, net of tax		(8.7)	[1]	0	0	0	0	0	(8.7)	0
Distribution of IPO proceeds to NiSource		0
Distribution to NiSource | Predecessor		0
Distribution to NiSource		0
Net transfers from NiSource		1.3		0	0	0	0	1.3	0	0
Ending Balance at Dec. 31, 2014										0
Stockholders' Equity		4,176.3		0	0	0	0	4,210.8	(34.5)
Net Income (Loss) Attributable to Parent		267.2		0	0	0	126.4	140.8	0
Income (Loss) Attributable to Noncontrolling Interest		39.9
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		5.3		0	0	0	0	0	5.3
Other Comprehensive Income, net of tax		5.4	[1]							0.1
Allocation of AOCI to noncontrolling interest		2.2		0	0	0	0	0	2.2	(2.2)
Issuance of common units of CPPL		0		0	0	0	0	0	0	1,168.4
Distribution of IPO proceeds to NiSource		(500)		0	0	0	0	(500)	0	0
Distribution to NiSource		(1,450)		0	0	0	0	(1,450)	0	0
Purchase of additional interest in Columbia OpCo		227.1		0	0	0	0	227.1	0	(227.1)
Distribution to noncontrolling interest		0		0	0	0	0	0	0	(23.2)
Net transfers from NiSource		6.3		0	0	0	0	6.3	0	0
Reclassification of net parent investment to additional paid-in capital		0		0	0	2,635	0	(2,635)	0	0
Issuance of common stock at Separation		0		3.2	0	(3.2)	0	0	0	0
Net transfers from NiSource subsequent to Separation		$ 1		$ 0	$ 0	$ 1	$ 0	$ 0	$ 0	$ 0.5
Issuance of common stock, net of offering costs		1,394.7		0.8	0	1,393.9	0	0	0	0
Common stock dividends	[2]	$ (79.5)		$ 0	$ 0	$ 0	$ (79.5)	$ 0	$ 0	$ 0
Long-term incentive plan		6		0	0	6	0	0	0	0
Ending Balance at Dec. 31, 2015		5,013								956.4
Stockholders' Equity		4,056.6		4	0	4,032.7	46.9	0	(27)
Net Income (Loss) Attributable to Parent		116.8		0	0	0	116.8	0	0
Income (Loss) Attributable to Noncontrolling Interest		37.1
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		3.1		0	0	0	0	0	3.1
Other Comprehensive Income, net of tax		3.3	[1]							0.2
Distribution of IPO proceeds to NiSource		0
Distribution to NiSource		0
Distribution to noncontrolling interest		0		0	0	0	0	0	0	(41)
Issuance of common stock at Separation		10,216.8		0.1	0	10,216.7	0	0	0	0
Common stock dividends	[2]	(105.1)		0	0	0	(105.1)	0	0	0
Dividend to TransCanada		(110.5)		0	0	0	(110.5)	0	0	0
Common stock purchased by TransCanada and retired		(10,216.7)		(4)	0	(10,212.7)	0	0	0	0
Treasury stock acquired		(6.2)		0	(6.2)	0	0	0	0	0
Treasury stock retired		0		0	6.2	(4.6)	(1.6)	0	0	0
Issuance of stock to TransCanada	[3]	500		0	0	500	0	0	0	0
Stock subject to accelerated vesting during period, share-based compensation, value		(18.3)		0	0	(18.3)	0	0	0	0.2
Ending Balance at Dec. 31, 2016		4,436.5								$ 952.9	[4]
Stockholders' Equity		$ 4,436.5		$ 0.1	$ 0	$ 4,513.8	$ (53.5)	$ 0	$ (23.9)
[1]	All amounts are net of tax. Amounts in parentheses indicate debits.
[2]	CPG declared and paid common dividends totaling $0.2625 per share and $0.25 per share for the years ended December 31, 2016 and 2015, respectively.
[3]	In December 2016, CPG issued 50 shares of common stock, $0.01 par value at a purchase price of $10.0 million per share, for a total of $500.0 million to US Parent.
[4]	As of December 31, 2016 and as a result of the CPPL Merger Agreement, CPPL's common units now contain a redemption feature within the control of CPPL's unaffiliated unitholders. The existence of the redemption feature causes CPG's noncontrolling interest to be redeemable at an amount other than fair value, thus requiring CPG to present noncontrolling interest as temporary equity on the Consolidated Balance Sheets. Please see Note 1, "Nature of Operations and Summary of Significant Accounting Policies" in the Notes to Consolidated and Combined Financial Statements for further discussion.

Statements of Consolidated and9

Statements of Consolidated and Combined Equity (Parenthetical) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Issuance of common units of CPPL			$ 0
Common Stock, Dividends, Per Share, Declared		$ 0.2625	$ 0.2500
Stock Issued During Period, Shares, Other		50
Common Stock, Par or Stated Value Per Share		$ 0.01	$ 0.01
Stock Issued During Period, Price per Share, Other		$ 10,000,000
Issuance of stock to TransCanada	[1]	$ 500
Columbia OpCo
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Additional Ownership Interest			8.40%
Noncontrolling Interest
Issuance of common units of CPPL			$ 1,168.4
Issuance of stock to TransCanada	[1]	$ 0
[1]	In December 2016, CPG issued 50 shares of common stock, $0.01 par value at a purchase price of $10.0 million per share, for a total of $500.0 million to US Parent.

Nature of Operations and Summar

Nature of Operations and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Significant Accounting Policies	Nature of Operations and Summary of Significant Accounting Policies A. Company Structure and Basis of 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. As a result of this contribution, the financial statements for periods as of and subsequent to September 26, 2014 reflect the consolidated financial position, results of operations and cash flows for CPG. All periods prior to September 26, 2014 reflect the combined financial position, results of operations and cash flows for CPG's Predecessor (the "Predecessor"). 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; • 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 year ended December 31, 2016 , CPG incurred Merger transaction costs of $66.6 million , including legal, advisory and other related fees. These costs are included in "Operation and maintenance" on the Statements of Consolidated and Combined Operations. Approximately $104.9 million of employee related costs were incurred subsequent to the Merger. Additionally as a result of the Merger, CPG recognized an impairment charge of $26.1 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 has also suspended its obligations to file periodic reports with the SEC based on its senior notes and once it has filed its Form 10-K for the year ended December 31, 2016, it will no longer have reporting obligations with respect to its senior notes. Refer to Note 6, "Long-Term Debt" for additional information on CPG's senior notes. CPPL Merger. On November 1, 2016, CPPL announced that it had entered into an agreement and plan of merger ("CPPL Merger Agreement") 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 CPPL Merger Agreement and transactions contemplated by the CPPL Merger Agreement and determined that the CPPL 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 CPPL Merger Agreement and the merger transactions. The GP Board resolved that the CPPL 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 CPPL Merger Agreement and the merger transactions at the special meeting of the unitholders. On February 16, 2017, the CPPL unaffiliated unitholders voted to approve the CPPL Merger. On February 17, 2017, CPG closed the transaction to acquire all outstanding publicly held common units valued at approximately $915 million . CPPL unaffiliated unitholders also received a regular quarterly distribution of $0.1975 per common unit and a pro-rated distribution for the period prior to the closing date. As a result of the CPPL Merger, CPPL became a wholly owned subsidiary of CPG. As of December 31, 2016 and as a result of the CPPL Merger Agreement, CPPL's common units now contain a redemption feature within the control of CPPL's unaffiliated unitholders. The existence of the redemption feature causes CPG's noncontrolling interest to be redeemable at an amount other than fair value, thus requiring CPG to present noncontrolling interest as temporary equity on the Consolidated Balance Sheets. The redeemable noncontrolling interest is recorded at its current book value and will be adjusted each period for net earnings and other comprehensive income attributable to the noncontrolling interest. As of December 31, 2016, CPG did not consider noncontrolling interest to be probable of becoming redeemable given the special meeting of CPPL's unitholders had not yet occurred and there could be no certainty the unaffiliated unitholders will vote to approve the merger. CPG’s accompanying Consolidated and Combined Financial Statements 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 Consolidated and Combined Financial Statements are equity method investments Hardy Storage, Millennium Pipeline and Pennant. B. Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. C. Cash and Cash Equivalents. Cash and cash equivalents are liquid marketable securities with an original maturity date of less than three months. D. Allowance for Uncollectible Accounts. The reserve for uncollectible receivables is CPG's best estimate of the amount of probable credit losses in the existing accounts receivable. Collectability of accounts receivable is reviewed regularly and an allowance is established or adjusted, as necessary, using the specific identification method. Account balances are charged against the allowance when it is anticipated the receivable will not be recovered. E. Basis of Accounting for Rate-Regulated Subsidiaries . Rate-regulated subsidiaries account for and report assets and liabilities consistent with the economic effect of the way in which regulators establish rates, if the rates established are designed to recover the costs of providing the regulated service and it is probable that such rates can be charged and collected. Certain expenses and credits subject to utility regulation or rate determination normally reflected in income are deferred on the Consolidated Balance Sheets and are recognized in income as the related amounts are included in service rates and recovered from or refunded to customers. In the event that regulation significantly changes the opportunity for CPG to recover its costs in the future, all or a portion of CPG’s regulated operations may no longer meet the criteria for regulatory accounting. In such an event, a write-down of all or a portion of CPG’s existing regulatory assets and liabilities could result. If CPG is unable to continue to apply the provisions of regulatory accounting, CPG would be required to apply the provisions of Discontinuation of Rate-Regulated Accounting. In management’s opinion, CPG’s regulated subsidiaries will be subject to regulatory accounting for the foreseeable future. Please see Note 11, "Regulatory Matters," in the Notes to Consolidated and Combined Financial Statements for further discussion. F. Property, Plant and Equipment and Related AFUDC and Maintenance . Property, plant and equipment is stated at cost. CPG's rate-regulated subsidiaries record depreciation using composite rates on a straight-line basis over the remaining service lives of the properties as approved by the appropriate regulators. CPG's non-regulated companies depreciate assets on a component basis on a straight-line basis over the remaining service lives of the properties. CPG capitalizes AFUDC on all classes of property except organization costs, land, autos, office equipment, tools and other general property purchases. The allowance is applied to construction costs for that period of time between the date of the expenditure and the date on which such project is placed in service. A combination of short-term borrowings, long-term debt and equity were used to fund construction efforts for all three years presented. The pre-tax rate for AFUDC debt and ADUFC equity are summarized in the table below: 2016 2015 2014 Debt Equity Debt Equity Debt Equity Columbia Gas Transmission 0.6 % 4.8 % 1.8 % 6.3 % 0.9 % 3.0 % Columbia Gulf 0.6 % 3.7 % 2.9 % 6.3 % 2.1 % 9.4 % CPG follows the practice of charging maintenance and repairs, including the cost of removal of minor items of property, to expense as incurred. When regulated property that represents a retired unit is replaced or removed, the cost of such property is credited to utility plant, and such cost, net of salvage, is charged to the accumulated provision for depreciation in accordance with composite depreciation. G. Gas Stored-Base Gas. Base gas, which is valued at original cost, represents storage volumes that are maintained to ensure that adequate well pressure exists to deliver current gas inventory. There were no purchases of base gas during the years ended December 31, 2016 , 2015 and 2014 . Gas stored-base gas is included in Property, plant and equipment on the Consolidated Balance Sheets. H. Amortization of Software Costs. External and internal costs associated with computer software developed for internal use are capitalized. Capitalization of such costs commences upon the completion of the preliminary stage of each project. Once the installed software is ready for its intended use, such capitalized costs are amortized on a straight-line basis generally over a period of five years. CPG amortized $20.4 million in 2016 , $8.7 million in 2015 and $4.3 million in 2014 related to software costs. CPG’s unamortized software balance was $72.1 million and $59.8 million at December 31, 2016 and 2015 , respectively. The increase in software amortization and unamortized software balance is primarily due to software placed in service subsequent to the Separation. The additional software was necessary for CPG to operate as an independent company. I. Goodwill. CPG has $1,975.5 million in goodwill. All goodwill relates to the excess of cost over the fair value of the net assets acquired in the CEG acquisition on November 1, 2000. Please see Note 9, "Goodwill," in the Notes to Consolidated and Combined Financial Statements for further discussion. J. Impairments. An impairment loss on long-lived assets shall be recognized only if the carrying amount of a long-lived assets is not recoverable and exceeds its fair value. The test for impairment compares the carrying amount of the long-lived asset to the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. CPG recognized an impairment loss of $26.1 million , $2.4 million and zero for the years ended December 31, 2016 , 2015 and 2014 , respectively. As a result of the Merger, CPG recognized an impairment loss for the year ended December 31, 2016 related to the cancellation of IT system upgrades that were in process prior to the Merger. K. Revenue Recognition. Revenue is recorded as services are performed. Revenues are billed to customers monthly at rates established through the FERC's cost-based rate-making process or at rates less than those allowed by the FERC. Revenues are recorded on the accrual basis and include estimates for transportation provided but not billed. The demand and commodity charges for transportation of gas under long-term agreements are recognized separately. Demand revenues are recognized monthly over the term of the agreement with the customer regardless of the volume of natural gas transported. Commodity revenues for both firm and interruptible transportation are recognized in the period the transportation services are provided based on volumes of natural gas physically delivered at the agreed upon delivery point. CPG provides shorter term transportation and storage services for which cash is received at inception of the service period resulting in the recording of deferred revenues that are recognized in revenues over the period the services are provided. Storage capacity revenues are recognized monthly over the term of the agreement with the customer regardless of the volume of storage service actually utilized. Injection and withdrawal revenues are recognized in the period when volumes of natural gas are physically injected into or withdrawn from storage. CPG includes the subsidiary CEVCO, which owns the mineral rights to approximately 460,000 acres in the Marcellus and Utica shale areas. CEVCO leases or contributes the mineral rights to producers in return for royalty interest. Royalties from mineral interests are recognized on an accrual basis when earned and realized. Royalty revenue was $21.5 million , $26.5 million and $43.8 million for the years ended December 31, 2016 , 2015 and 2014 , respectively, and is included in "Other revenues" on the Statements of Consolidated and Combined Operations. CPG periodically recognizes gains on the conveyance of mineral interest related to pooling of assets (production rights) in joint undertakings intended to find, develop, or produce oil or gas from a particular property or group of properties. The gains are initially deferred if CPG has a substantial obligation for future performance. As the obligation for future performance is satisfied, the deferred revenue is relieved and the associated gain is recognized. Gains on conveyances amounted to $16.9 million , $52.3 million and $34.5 million for the years ended December 31, 2016 , 2015 and 2014 , respectively, and are included in "Gain on sale of assets" on the Statements of Consolidated and Combined Operations. L. Estimated Rate Refunds . CPG collects revenue subject to refund pending final determination in rate proceedings. In connection with such revenues, estimated rate refund liabilities are recorded which reflect management’s current judgment of the ultimate outcomes of the proceedings. No provisions are made when, in the opinion of management, the facts and circumstances preclude a reasonable estimate of the outcome. M. Accounting for Exchange and Balancing Arrangements of Natural Gas. CPG enters into balancing and exchange arrangements of natural gas as part of its operations. CPG records a receivable or payable for its respective cumulative gas imbalances. These receivables and payables are recorded as “Exchange gas receivable” or “Exchange gas payable” on CPG’s Consolidated Balance Sheets, as appropriate. N. Income Taxes and Investment Tax Credits. CPG records income taxes to recognize full inter period tax allocations. Under the liability method, deferred income taxes are provided for the tax consequences of temporary differences by applying enacted statutory tax rates applicable to future years to differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities. To the extent certain deferred income taxes of CPG are recoverable or payable through future rates, regulatory assets and liabilities have been established. Subsequent to the Merger, CPG is included in the consolidated Federal income tax return filed by US Parent and is a party to a Federal Tax Allocation Agreement with US Parent. The tax allocation agreement 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. In prior years, and for the period ending July 1, 2015, CPG joined in the filing of consolidated federal and state income tax returns with NiSource. CPG was a party to an agreement (“Tax Allocation Agreement”) that provides for the allocation of consolidated tax liabilities. The Tax Allocation Agreement generally provides that each party is allocated an amount of tax similar to that which would be owed had the party been separately subject to tax. In addition, the Tax Allocation Agreement provides that tax benefits associated with NiSource parent’s tax losses, excluding tax benefits from interest expense on acquisition debt, are allocated to and reduce the income tax liability of all NiSource subsidiaries having a positive separate company tax liability in a particular tax year. The amounts of such tax benefits allocated to CPG that were recorded in equity in 2016 , 2015 and 2014 were zero , $5.8 million and $1.3 million , respectively. O. Environmental Expenditures. CPG accrues for costs associated with environmental remediation obligations when the incurrence of such costs is probable and the amounts can be reasonably estimated, regardless of when the expenditures are actually made. The undiscounted estimated future expenditures are based on currently enacted laws and regulations, existing technology and estimated site-specific costs where assumptions may be made about the nature and extent of site contamination, the extent of cleanup efforts, costs of alternative cleanup methods and other variables. The liability is adjusted as further information is discovered or circumstances change. The reserves for estimated environmental expenditures are recorded on the Consolidated Balance Sheets in “Other Accruals” for short-term portions of these liabilities and “Other noncurrent liabilities” for the respective long-term portions of these liabilities. CPG establishes regulatory assets on the Consolidated Balance Sheets to the extent that future recovery of environmental remediation costs is probable through the regulatory process. Please see Note 17, "Other Commitments and Contingencies" in the Notes to Consolidated and Combined Financial Statements for further discussion. P. Accounting for Investments. CPG accounts for its ownership interests in Millennium Pipeline using the equity method of accounting. Columbia Gas Transmission owns a 47.5% interest in Millennium Pipeline. The equity method of accounting is applied for investments in unconsolidated companies where CPG (or a subsidiary) owns 20 to 50 percent of the voting rights and can exercise significant influence. CPG owns a 50.0% interest in Hardy Storage for the periods presented. CPG reflects the investment in Hardy Storage as an equity method investment. Columbia Midstream entered into a 50:50 joint venture in 2012 with Hilcorp to construct Pennant, a new wet natural gas gathering infrastructure and NGL processing facilities to support natural gas production in the Utica Shale region of northeastern Ohio and western Pennsylvania. During the third quarter of 2015, an additional member, an affiliate of Williams Partners, joined the Pennant joint venture. Williams Partners' initial ownership investment in Pennant is 5.00% , and by funding specified investment amounts for future growth projects, Williams Partners can invest directly in the growth of Pennant. Such funding will potentially increase Williams Partners' 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 50.0% to 47.5% . During 2016, Williams Partners funded additional specified growth projects. As a result Columbia Midstream's ownership interest decreased to 47.0% . CPG accounts for the joint venture under the equity method of accounting. Q. Natural Gas and Oil Properties. CEVCO participates as a working interest partner in the development of a broader acreage dedication. The working interest allows CEVCO to invest in the drilling operations of the partnership in addition to a royalty interest in well production. Please see Note 1K, “Revenue Recognition,” in the Notes to Consolidated and Combined Financial Statements for further discussion regarding the royalty revenue. CEVCO uses the successful efforts method of accounting for natural gas and oil producing activities for their portion of drilling activities. Capitalized well costs are depleted based on the units of production method. CEVCO’s portion of unproved property investment is periodically evaluated for impairment. The majority of these costs generally relate to CEVCO’s portion of the working interest. The costs are capitalized and evaluated as to recoverability, based on changes brought about by economic factors and potential shifts in business strategy employed by management. Impairment of individually significant unproved property is assessed on a field-by-field basis considering a combination of time, geologic and engineering factors. The following table reflects the changes in capitalized exploratory well costs for the years ended December 31, 2016 and 2015 : (in millions) 2016 2015 Beginning Balance $ 1.7 $ 14.9 Additions pending the determination of proved reserves — 1.3 Reclassifications of proved properties (1.3 ) (14.5 ) Ending Balance $ 0.4 $ 1.7 As of December 31, 2016 , there was $0.3 million of capitalized exploratory well costs that have been capitalized for more than one year relating to one project initiated in 2013.

CPPL Initial Public Offering

CPPL Initial Public Offering	12 Months Ended
	Dec. 31, 2016
Initial Public Offering [Abstract]
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 into CPG's results. As of December 31, 2016 , the portion of CPPL owned by the public is reflected as a noncontrolling interest in the Consolidated and Combined Financial Statements. The table below summarizes the effects of the changes in CPG's ownership interest in Columbia OpCo on equity: Year Ended December 31, (in millions) 2016 2015 Net income attributable to CPG $ 116.8 $ 267.2 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 $ 116.8 $ 494.3

Recent Accounting Pronouncement

Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements In January 2017, the FASB issued ASU 2017-04, Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment . ASU 2017-04 simplifies how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. CPG is required to adopt ASU 2017-04 for its annual or any interim goodwill impairment tests for annual periods beginning after December 15, 2019, and the guidance is to be applied on a prospective basis. CPG is currently evaluating the impact the adoption of ASU 2017-04 will have on the Consolidated and Combined Financial Statements and Notes to Consolidated and Combined Financial Statements. In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business , to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill and consolidation. ASU 2017-01 provides a framework that gives entities a basis for making reasonable judgments about whether a transaction involves an asset or a business. CPG is required to adopt ASU 2017-01 for periods beginning after December 15, 2017, including interim periods, and the guidance is to be applied on a prospective basis. CPG is currently evaluating the impact the adoption of ASU 2017-01 will have on the Consolidated and Combined Financial Statements and Notes to Consolidated and Combined Financial Statements. In October 2016, the FASB issued ASU 2016-17, Consolidation (Topic 810): Interests Held through Related Parties that are Under Common Control , which amends the guidance on related parties that are under common control. Specifically, ASU 2016-17 requires that a single decision maker consider indirect interest held by related parties under common control on a proportionate basis in a manner consistent with its evaluation of indirect interests held through other related parties. CPG is required to adopt ASU 2016-17 for periods beginning after December 15, 2016, including interim periods, and the guidance is to be applied on a retrospective basis. CPG is currently evaluating the impact the adoption of ASU 2016-17 will have on the Consolidated and Combined Financial Statements and Notes to Consolidated and Combined Financial Statements but does not anticipate the impact will be material. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Asset Transfers of Assets Other Than Inventory , which removes the prohibition in ASC 740 against the immediate recognition of the current and deferred income tax effects of intra-entity transfers of assets other than inventory. CPG is required to adopt ASU 2016-16 for periods beginning after December 15, 2017, including interim periods, and the guidance is to be applied on a modified retrospective basis, with early adoption permitted. CPG is currently evaluating the impact the adoption of ASU 2016-16 will have on the Consolidated and Combined Financial Statements and Notes to Consolidated and Combined Financial Statements. 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 Consolidated and Combined Financial Statements or Notes to Consolidated and Combined Financial Statements. 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 identifying existing customer contracts or groups of contracts that are within the scope of the new guidance and has begun an assessment in order to determine the impact the adoption of ASU 2014-09, and the related ASUs, will have on the Consolidated and Combined Financial Statements or Notes to Consolidated and Combined Financial Statements. 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. Among other provisions, ASU 2016-09 requires that all income tax effects of awards are recognized in the income statement when the awards vest or are settled and also allows an employer to make a policy election to account for forfeitures as they occur. CPG is required to adopt ASU 2016-09 for periods beginning after December 15, 2016, including interim periods, with early adoption permitted if all of the amendments are adopted in the same period. Each amendment has varying transition requirements. CPG expects to adopt ASU 2016-09 in the first quarter of 2017. Upon adoption, CPG will record a $9.9 million increase to beginning retained earnings with a corresponding increase in deferred tax assets representing the excess tax benefits generated in years prior to adoption of ASU 2016-09. Prior to the adoption of ASU 2016-09, CPG was precluded from recording this increase in deferred tax assets due to having a cumulative net operating loss carryforward for Federal income taxes. 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 identifying existing lease agreements that may have an impact on the Consolidated and Combined Financial Statements or Notes to Consolidated and Combined Financial Statements. 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 Consolidated Balance Sheets and Notes to Consolidated and Combined Financial Statements. 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 Consolidated and Combined Financial Statements or Notes to Consolidated and Combined Financial Statements.

Transactions with Affiliates

Transactions with Affiliates	12 Months Ended
	Dec. 31, 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 $2.1 million for the year ended December 31, 2016. Accounts Receivable . The affiliated accounts receivable balance of $55.8 million due from TransCanada primarily represents amounts allocated to CPG pursuant to TransCanada's tax allocation agreement. Accounts Payable . The affiliated accounts payable balance of $4.0 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 per annum, (b) the reference prime rate per annum as defined by Bloomberg Professional Service or (c) the rate equal to LIBOR for a one month LIBOR period for each day the loan is outstanding, plus 1.000 percent per annum, each of which is subject to a margin of 0.250 percent per annum, or (ii) the LIBOR rate plus a margin of 1.250 percent per annum. As of December 31, 2016 , CPG had no outstanding borrowings under the revolving credit facility, with a weighted average interest rate of 1.98% . Dividends to TransCanada . Subsequent to the completion of the Merger, CPG distributed $110.5 million to TransCanada for the year ended December 31, 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 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 year ended December 31, 2015 , CPG recognized transportation revenues of $47.5 million , storage revenues of $26.2 million and other revenues of $0.2 million . For the year ended December 31, 2014 , CPG recognized transportation revenues of $95.7 million , storage revenues of $53.2 million and other revenues of $0.3 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 years ended December 31, 2015 and 2014 , operation and maintenance expense was $52.9 million and $123.2 million , respectively. 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. CPG was charged interest for long-term debt of $31.0 million and $61.6 million for the years ended December 31, 2015 and 2014 , respectively, offset by associated AFUDC of $2.4 million and $2.7 million for the years ended December 31, 2015 and 2014 , respectively. Columbia OpCo and its subsidiaries entered into an intercompany money pool agreement with NiSource Finance, which became effective on the closing date of CPPL's IPO. 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 June 30, 2015 was 1.21% . The interest expense for short-term borrowings charged for the years ended December 31, 2015 and 2014 was $0.7 million and $3.1 million , respectively. Dividends to NiSource . During the year ended December 31, 2015 , CPG distributed $500.0 million of the proceeds from CPPL's IPO to NiSource as a reimbursement of preformation capital expenditures with respect to the assets contributed to Columbia OpCo and $1,450.0 million of proceeds related to the issuance of senior notes in May 2015. CPG paid no dividends to NiSource in the year ended December 31, 2014 . There were no restrictions on the payment by CPG of dividends to NiSource.

Short-Term Borrowings

Short-Term Borrowings	12 Months Ended
	Dec. 31, 2016
Short-term Debt [Abstract]
Short-Term Borrowings	Short-Term Borrowings New CPG Revolving Credit Facility. On December 16, 2016, CPG entered into a $1,000.0 million senior revolving credit facility. The revolving credit facility is guaranteed by TCPL. The initial maturity date is December 15, 2017, subject to an extension permitted under the revolving credit facility. CPG expects that the revolving credit facility will be utilized for the financing of capital expenditures and for CPG’s general corporate purposes, including working capital. Obligations under the revolving credit facility are unsecured. Loans under the revolving credit facility will bear interest at CPG's option at either (i) LIBOR plus a margin ranging from 0.75% to 1.25% or (ii) a base rate plus a margin ranging from 0.00% to 0.25% , in each case, depending upon the credit rating of the TCPL’s senior, unsecured, long-term debt (the "Index Debt Rating"). In addition, CPG is obligated to pay a quarterly commitment fee equal to a rate per annum ranging from 0.04% to 0.15% , depending upon the Index Debt Rating, and calculated daily based on the unused commitments during such previous quarter. TCPL shall comply, and shall cause CPG and each of TCPL’s subsidiaries to comply, with a number of customary affirmative and negative covenants, including limitations with respect to liens, indebtedness, distributions, mergers, consolidations, and asset sales, among others. TCPL shall not, and shall not permit any of its subsidiaries to, incur additional indebtedness (other than indebtedness maturing 24 months or less after such indebtedness is incurred) if immediately after incurring such indebtedness, the ratio of indebtedness of TCPL and its subsidiaries (on a consolidated basis) to the total capitalization of TCPL and its subsidiaries (on a consolidated basis) would be in excess of 0.75 to 1.00 . A breach of any of these covenants could result in a default in respect of the related debt. If a default occurred, the relevant lenders could elect to declare the debt, together with accrued interest and other fees, to be immediately due and payable (subject to applicable grace periods). As of December 31, 2016 , CPG had no outstanding borrowings under the revolving credit facility. As of December 31, 2015 , CPG had no outstanding borrowings and had $18.1 million in letters of credit under the previous 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 is included in interest expense for the year ended December 31, 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 is included in interest expense for the year ended December 31, 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 Statements of Consolidated and Combined Cash Flows.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2016
Long-term Debt, Current and Noncurrent [Abstract]
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 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. First, if CPG discharges or defeases its obligations with respect to the Notes of any series, then any guarantee will be released with respect to that series. Second, if no event of default has occurred and is continuing under the Indenture, a Guarantor will be automatically and unconditionally released and discharged from its guarantee (i) at any time after June 1, 2018, upon any sale, exchange or transfer, whether by way of merger or otherwise, to any person that is not CPG’s affiliate, of all of CPG’s direct or indirect limited partnership, limited liability or other equity interests in the Guarantor; (ii) upon the merger of a guarantor into CPG or any other Guarantor or the liquidation and dissolution of such Guarantor; or (iii) at any time after June 1, 2018, upon release of all guarantees or other obligations of the Guarantor with respect to any of CPG’s funded debt, except the Notes. The Indenture governing the Notes, dated as of May 22, 2015, contains covenants that, among other things, limit the ability of CPG and certain of its subsidiaries to incur liens, to enter into sale and lease-back transactions and to enter into mergers, consolidations or transfers of all or substantially all of their assets. The Indenture also contains customary events of default. The 2018 Notes will mature on June 1, 2018 , the 2020 Notes will mature on June 1, 2020 , the 2025 Notes will mature on June 1, 2025 and the 2045 Notes will mature on June 1, 2045 . Interest on the Notes of each series will be payable semi-annually in arrears on June 1 and December 1. 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. The exchange offer contemplated by the registration statement expired on May 12, 2016. A post-effective amendment to the registration statement was filed on January 30, 2017 to terminate the registration of any senior notes under the registration statement that remained unexchanged. The following table summarizes the aggregate maturities of long-term debt outstanding as of December 31, 2016 : Year Ending December 31, (in millions) 2017 $ — 2018 500.0 2019 — 2020 750.0 2021 — After 1,500.0 Total (1) $ 2,750.0 (1) This amount excludes unamortized discount and unamortized debt issuance costs of $3.4 million and $18.0 million , respectively. The unamortized discount and unamortized debt issuance costs applicable to the Notes are being amortized over the weighted average life of the Notes.

Gain on Sale of Assets

Gain on Sale of Assets	12 Months Ended
	Dec. 31, 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 years ended December 31, 2016 , 2015 and 2014 , gains on conveyances amounted to $16.9 million , $52.3 million and $34.5 million , respectively, and are included in "Gain on sale of assets" on the Statements of Consolidated and Combined Operations. Included in the gains on conveyances is a cash bonus payment of $9.0 million and $35.8 million received by CEVCO during the years ended December 31, 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 December 31, 2016 and 2015 , deferred gains of approximately $0.3 million and $8.1 million , respectively, were deferred pending performance of future obligations and recorded in "Deferred revenue" on the Consolidated Balance Sheets.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment CPG’s property, plant and equipment on the Consolidated Balance Sheets are classified as follows: At December 31, (in millions) 2016 2015 Property, plant and equipment Pipeline and other transmission assets $ 6,681.2 $ 6,160.4 Storage facilities 1,415.3 1,370.1 Gas stored base gas 299.5 299.5 Gathering and processing facilities 566.9 370.2 Construction work in process 1,097.0 487.6 General plant, software, and other assets 401.3 364.5 Property, plant and equipment 10,461.2 9,052.3 Accumulated depreciation and amortization (3,126.2 ) (2,988.6 ) Net property, plant and equipment $ 7,335.0 $ 6,063.7 The table below lists CPG's applicable annual depreciation rates: Year Ended December 31, 2016 2015 2014 Depreciation rates Pipeline and other transmission assets 1.00% - 2.50% 1.00% - 2.50% 1.00% - 2.50% Storage facilities 2.19% - 3.00% 2.19% - 3.00% 2.19% - 3.30% Gathering and processing facilities 1.67% - 2.50% 1.67% - 2.50% 1.67% - 2.50% General plant, software, and other assets 1.00% - 20.00% 1.00% - 21.00% 1.00% - 10.00%

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 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 December 31, 2016 and December 31, 2015 were $1,975.5 million . The 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. In estimating the fair value of Columbia Gas Transmission Operations for the May 1, 2012 test, the Predecessor used a weighted average of the income and market approaches. The income approach utilized a discounted cash flow model. This model was based on management’s short-term and long-term forecast of operating performance for each reporting unit. The two main assumptions used in the models were the growth rates, which were based on the cash flows from operations for the reporting unit, and the weighted average cost of capital, or discount rate. The starting point for the reporting unit’s cash flow from operations was the detailed five year plan, which takes into consideration a variety of factors such as the current economic environment, industry trends, and specific operating goals set by management. The discount rates were based on trends in overall market as well as industry specific variables and include components such as the risk-free rate, cost of debt, and company volatility at May 1, 2012. Under the market approach, the Predecessor utilized three market-based models to estimate the fair value of the reporting unit: (i) the comparable company multiples method, which estimated fair value of the reporting unit by analyzing EBITDA multiples of a peer group of publicly traded companies and applying that multiple to the reporting unit’s EBITDA, (ii) the comparable transactions method, which valued the reporting unit based on observed EBITDA multiples from completed transactions of peer companies and applying that multiple to the reporting unit’s EBITDA, and (iii) the market capitalization method, which used the NiSource share price and allocated NiSource’s total market capitalization among both the goodwill and non-goodwill reporting units based on the relative EBITDA, revenues, and operating income of each reporting unit. Each of the three market approaches were calculated with the assistance of a third-party valuation firm, using multiples and assumptions inherent in today’s market. The degree of judgment involved and reliability of inputs into each model were considered in weighting the various approaches. The resulting estimate of fair value of the reporting unit, using the weighted average of the income and market approaches, exceeded its carrying value, indicating that no impairment exists under step 1 of the annual impairment test. Certain key assumptions used in determining the fair value of the reporting unit included planned operating results, discount rates and the long-term outlook for growth. In 2012, the Predecessor used the discount rate of 5.60% for Columbia Gas Transmission Operations, resulting in excess fair value of approximately $1,643.0 million . 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 the 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 the 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 goodwill impairment testing subsequent to May 1, 2016.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2016
Asset Retirement Obligation [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations Changes in CPG’s liability for asset retirement obligations for the years 2016 and 2015 are presented in the table below: (in millions) 2016 2015 Beginning Balance $ 25.7 $ 23.2 Accretion expense 1.1 1.2 Additions — 4.1 Change in estimated cash flows (6.0 ) (2.8 ) Ending Balance $ 20.8 $ 25.7 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	12 Months Ended
	Dec. 31, 2016
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Matters	Regulatory Matters Regulatory Assets and Liabilities Current and noncurrent regulatory assets and liabilities were comprised of the following items: At December 31, (in millions) 2016 2015 Assets Unrecognized pension benefit and other postretirement benefit costs $ 111.3 $ 135.2 Other postretirement costs 6.3 9.0 Deferred taxes on AFUDC equity 57.0 35.4 Other 2.3 3.1 Total Regulatory Assets $ 176.9 $ 182.7 At December 31, (in millions) 2016 2015 Liabilities Cost of removal $ 141.5 $ 154.7 Regulatory effects of accounting for income taxes 10.2 10.6 Modernization revenue sharing 7.4 — Other postretirement costs 134.3 155.6 Other — 1.9 Total Regulatory Liabilities $ 293.4 $ 322.8 No regulatory assets are earning a return on investment at December 31, 2016 . Regulatory assets of $58.9 million are covered by specific regulatory orders and are being recovered as components of cost of service over a remaining life of up to 6 years. Assets: Unrecognized pension benefit and other postretirement benefit costs – In 2007, the Predecessor adopted certain updates of ASC 715 which required, among other things, the recognition in other comprehensive income or loss of the actuarial gains or losses and the prior service costs or credits that arise during the period but that are not immediately recognized as components of net periodic benefit costs. Certain subsidiaries defer the costs as a regulatory asset in accordance with regulatory orders to be recovered through base rates. Other postretirement costs – Primarily comprised of costs approved through rate orders to be collected through future base rates, revenue riders or tracking mechanisms. Deferred taxes on AFUDC equity - ASC 740 considers the equity component of AFUDC a temporary difference for which deferred income taxes must be provided. CPG is required to record the deferred tax liability for the equity component of AFUDC offset to this regulatory asset for wholly-owned subsidiaries and equity method investments. The regulatory asset is itself a temporary difference for which deferred incomes taxes are recognized. Liabilities: Cost of removal - Represents anticipated costs of removal that have been, and continue to be, included in depreciation rates and collected in the service rates of some rate-regulated subsidiaries for future costs to be incurred. Regulatory effects of accounting for income taxes - Represents amounts related to state income taxes collected at a higher rate than the current statutory rates assumed in rates, which is being amortized to earnings in association with depreciation on related property. Modernization revenue sharing - Represents amounts related to the revenue sharing mechanism within the Columbia Gas Transmission modernization program. The revenue sharing mechanism requires Columbia Gas Transmission to share 75% of specified revenues in excess of an annual threshold. Other postretirement costs - Primarily represents amounts being collected through rates in excess of the GAAP expense on a cumulative basis. In addition, according to regulatory order, a certain level of benefit expense is recognized in the CPG's results, which exceeds the amount funded in the plan. Regulatory Matters Columbia Gas Transmission Customer Settlement. On January 24, 2013, the FERC approved the Columbia Gas Transmission Customer Settlement (the "MOD I Settlement"). In March 2013, Columbia Gas Transmission paid $88.1 million in refunds to customers pursuant to the MOD I Settlement with its customers in conjunction with its comprehensive interstate natural gas pipeline modernization program. The refunds were made as part of the Settlement, which included a $50.0 million refund to max rate contract customers and a base rate reduction retroactive to January 1, 2012. Columbia Gas Transmission expects to invest approximately $1.5 billion over a five-year period, which began in 2013, to modernize its system to improve system integrity and enhance service reliability and flexibility. The MOD I Settlement with firm customers included an initial five-year term with provisions for potential extensions thereafter. The MOD I Settlement also provided for a depreciation rate reduction to 1.5% and elimination of negative salvage rate effective January 1, 2012 and for a second base rate reduction, which began January 1, 2014, which equates to approximately $25.0 million in revenues annually thereafter. The MOD I Settlement includes a CCRM, a tracker mechanism that will allow Columbia Gas Transmission to recover, through an additive capital demand rate, its revenue requirement for capital investments made under Columbia Gas Transmission's long-term plan to modernize its interstate transmission system. The CCRM provides for a 14.0% revenue requirement with a portion designated as a recovery of taxes other than income taxes. The additive demand rate is earned on costs associated with projects placed into service by October 31 each year. The initial additive demand rate was effective on February 1, 2014. The CCRM will give Columbia Gas Transmission the opportunity to recover its revenue requirement associated with a $1.5 billion investment in the modernization program. The CCRM recovers the revenue requirement associated with qualifying modernization costs that Columbia Gas Transmission incurs after satisfying the requirement associated with $100.0 million in annual maintenance capital expenditures. The CCRM applies to Columbia Gas Transmission's transportation shippers. The CCRM will not exceed $300.0 million per year in investment in eligible facilities, subject to a 15.0% annual tolerance and a total cap of $1.5 billion for the entire five-year initial term. On January 31, 2017, Columbia Gas Transmission received FERC approval of its December 2016 filing to recover costs associated with the fourth year of its comprehensive system modernization program. In 2016, Columbia Gas Transmission placed approximately $330.0 million in modernization investments into service, bringing the total gross investment to approximately $1.3 billion over the four year period. The program includes replacement of bare steel and wrought iron pipeline and compressor facilities, enhancements to system inspection capabilities and improvements in control systems. On March 17, 2016, Columbia Gas Transmission received approval from the Commission of its December 18, 2015 filing for the Modernization II Settlement (the "MOD II Settlement"). The MOD II Settlement continues a rate mechanism that was designed to enable Columbia Gas Transmission to recover costs associated with a multi-year modernization program focused on replacing, rehabilitating and/or rebuilding critical pipeline infrastructure and ensuring the safety and reliability of the Columbia Gas Transmission system. The MOD II Settlement preserves and extends the core elements of the MOD I Settlement between Columbia Gas Transmission and its shippers that addressed previous modernization issues on the Columbia Gas Transmission system for three additional years. Columbia Gas Transmission expects to invest approximately $1.1 billion over the three-year extension period. Among other things, the MOD II Settlement preserves the MOD I Settlement’s $60.0 million base rate reduction and extends for a second term the CCRM that allows Columbia Gas Transmission to make annual limited filings under Section 4 of the Natural Gas Act to charge an additive capital demand rate in order to recover the revenue requirement related to certain eligible projects. The MOD II Settlement includes an additional reduction in base rates equal to approximately $8.4 million annually effective as of January 1, 2016, discontinuing the collection of OPEB costs no longer required because of the substantial over-recovered position, and a further base rate reduction equal to approximately $12.4 million annually for a 6-year period also beginning January 1, 2016, which basically refunds amounts to customers as a result of the over-collection of OPEB costs. Columbia Gas Transmission's base rates will reset effective February 1, 2019, without the need for a rate case, and a simultaneous reduction in those base rates equal to $7.5 million annually. The MOD II Settlement includes a one-time $5.0 million settlement payment effective after FERC’s approval of the 5th year CCRM for recovery under the first phase; payment would not be expected until 2018, and a revenue sharing mechanism, which requires Columbia Gas Transmission to share 50.0% of specified revenues in excess of an annual threshold. Columbia Gas Transmission has agreed to maintain a transmission depreciation rate of 1.5% , a storage depreciation rate of 2.2% , a negative salvage rate of zero percent and a moratorium through January 31, 2022 to changes in Columbia Gas Transmission’s base rates. The MOD II Settlement includes specified storage projects as eligible facilities whereby Columbia Gas Transmission may undertake construction of additional eligible facility projects in 2016-2017, with cost recovery on those projects beginning in 2019. 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. Under section 4 of the NGA, the FERC allows for the recovery of certain operating costs of our interstate transmission and storage companies that are significant and recurring in nature 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 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. A significant portion of our revenues and expenses are related to the recovery of costs under these tracking mechanisms. The associated costs for which we are obligated are reported in operating expenses with the offsetting recoveries reflected in revenues. These costs include: third-party transportation, electric compression, and certain approved operational purchases of natural gas. The tracking of certain environmental costs ended in 2015. Additionally, we recover fuel for company used gas and lost and unaccounted for gas through in-kind trackers where a retainage rate is charged to each customer to collect fuel. The recoveries and costs are both reflected in operating expenses.

Equity Method Investments

Equity Method Investments	12 Months Ended
	Dec. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Variable Interest Entities And 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 CPG's Consolidated Balance Sheets and CPG's portion of the results is reflected in "Equity Earnings in Unconsolidated Affiliates" on CPG's Statements of Consolidated and Combined Operations. In the normal course of business, CPG engages in various transactions with these unconsolidated affiliates. CPG billed approximately $10.5 million and $13.1 million to Millennium Pipeline for services and other costs during the years ended December 31, 2016 and 2015 , respectively. These investments are integral to CPG's business. Contributions are made to these equity investees to fund CPG's share of projects. The following is a list of CPG's equity method investments at December 31, 2016 : Investee Type of Investment % of Voting Power or Interest Held Hardy Storage Company, LLC LLC Membership 50.0 % Pennant Midstream, LLC LLC Membership 47.0 % Millennium Pipeline Company, L.L.C. LLC Membership 47.5 % As the Millennium Pipeline, Hardy Storage and Pennant investments are considered, in aggregate, material to CPG's business, the following table contains condensed summary financial data. Year Ended December 31, (in millions) 2016 2015 2014 Millennium Pipeline Statement of Income Data: Net Revenues $ 205.0 $ 206.3 $ 190.5 Operating Income 138.1 136.1 128.8 Net Income 102.5 98.0 89.6 Balance Sheet Data: Current Assets 34.8 35.7 32.1 Noncurrent Assets 969.8 987.1 1,016.3 Current Liabilities 48.0 44.4 42.6 Noncurrent Liabilities 497.2 535.8 568.3 Total Members’ Equity 459.4 442.6 437.5 Contribution/Distribution Data: (1) Contributions to Millennium Pipeline 6.2 1.4 2.6 Distribution of earnings from Millennium Pipeline 48.9 47.5 35.6 Hardy Storage Statement of Income Data: Net Revenues $ 23.5 $ 23.4 $ 23.6 Operating Income 15.7 15.3 16.1 Net Income 11.2 10.3 10.6 Balance Sheet Data: Current Assets 10.3 12.1 12.0 Noncurrent Assets 151.3 155.5 157.4 Current Liabilities 17.2 19.3 17.1 Noncurrent Liabilities 57.5 68.5 77.4 Total Members’ Equity 86.9 79.8 74.9 Contribution/Distribution Data: (1) Contributions to Hardy Storage — — — Distribution of earnings from Hardy Storage 2.0 2.6 2.2 Pennant Statement of Income Data: Net Revenues $ 38.2 $ 34.6 $ 8.5 Operating Income (Loss) 21.2 17.8 (2.4 ) Net Income (Loss) 21.2 17.8 (2.4 ) Balance Sheet Data: Current Assets 9.8 11.0 23.7 Noncurrent Assets 384.0 389.6 380.0 Current Liabilities 3.5 8.4 8.6 Total Members’ Equity 390.3 392.2 395.1 Contribution/Distribution Data: (1) Contributions to Pennant — — 66.6 Distribution of earnings from Pennant 10.6 7.1 — Return of capital from Pennant 2.2 16.0 — (1) Contribution and distribution data represents CPG's portion based on CPG's ownership percentage of each investment.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of income tax expense were as follows: Year Ended December 31, (in millions) 2016 2015 2014 Income Taxes Current Federal $ (55.7 ) $ 12.1 $ 19.5 State 4.2 9.1 7.6 Total Current (51.5 ) 21.2 27.1 Deferred Federal 116.3 120.2 119.2 State 13.0 11.6 23.5 Total Deferred 129.3 131.8 142.7 Deferred Investment Credits — — (0.1 ) Total Income Taxes $ 77.8 $ 153.0 $ 169.7 Total income taxes from continuing operations were different from the amount that would be computed by applying the statutory federal income tax rate to book income before income tax. The major reasons for this difference were as follows: Year Ended December 31, (in millions) 2016 2015 2014 Book income from Continuing Operations before income taxes $ 231.5 $ 460.5 $ 438.4 Tax expense at statutory federal income tax rate 81.0 35.0 % 161.2 35.0 % 153.5 35.0 % Increases (reductions) in taxes resulting from: State income taxes, net of federal income tax benefit 11.2 4.8 13.4 2.9 20.3 4.6 Noncontrolling interest (13.0 ) (5.6 ) (14.0 ) (3.0 ) — — AFUDC-Equity (11.2 ) (4.8 ) (9.2 ) (2.0 ) (3.7 ) (0.8 ) Transaction cost 8.7 3.8 — — — — Other, net 1.1 0.4 1.6 0.3 (0.4 ) (0.1 ) Total Income Taxes $ 77.8 33.6 % $ 153.0 33.2 % $ 169.7 38.7 % The effective income tax rates were 33.6% , 33.2% and 38.7% in 2016 , 2015 and 2014 , respectively. The overall effective tax rates in 2016 and 2015 are comparable. The 5.5% decrease in the overall effective tax rate in 2015 versus 2014 was primarily due to income received following CPPL’s IPO that is not subject to income tax at the partnership level, as well as state income taxes, utility rate making and other permanent book-to-tax differences. On December 18, 2015, the President signed into law the Protecting Americans from Tax Hikes Act of 2015 (PATH). PATH, among other things, permanently extends and modifies the research credit under Internal Revenue Code Section 41, and extends bonus depreciation (additional first-year depreciation) under a phase-down through 2019, as follows: • At 50% for 2015-2017; • At 40% in 2018; and • At 30% in 2019. In general, 50% bonus depreciation is available for qualified property placed in service in 2015, and in the following years, using the percentages above. CPG recorded the bonus depreciation effects of PATH for 2015 in the fourth quarter 2015. The permanent extension of the research credit did not have a significant effect on net income. On December 19, 2014, the President signed into law the Tax Increase Prevention Act ("TIPA"). TIPA extended and modified 50% bonus depreciation for 2014. CPG recorded the effects of TIPA in the fourth quarter 2014. In general, 50% bonus depreciation is available for property placed in service before January 1, 2015, or in the case of certain property having longer production periods, before January 1, 2016. The retroactive extension of the research credit did not have a significant effect on net income. In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. Among other provisions, the standard requires that all income tax effects of awards are recognized in the income statement when the awards vest or are settled and also allows an employer to make a policy election to account for forfeitures as they occur. CPG is required to adopt ASU 2016-09 for periods beginning after December 15, 2016, including interim periods, with early adoption permitted if all of the amendments are adopted in the same period. Each amendment has varying transition requirements. CPG expects to adopt ASU 2016-09 in the first quarter of 2017. Upon adoption, CPG will record a $9.9 million increase to beginning retained earnings with a corresponding increase in deferred tax assets representing the excess tax benefits generated in years prior to adoption of ASU 2016-09. Prior to the adoption of ASU 2016-09, CPG was precluded from recording this increase in deferred tax assets due to having a cumulative net operating loss carryforward for Federal income taxes. In November 2015, the FASB issued ASU 2015-17 simplifying the presentation of accumulated deferred income taxes on the balance sheet. ASU 2015-17 eliminated the requirement to separate deferred tax liabilities and assets into a current amount and a noncurrent amount on the balance sheet. ASU 2015-17 simplifies the presentation of ADIT by requiring ADIT liabilities and ADIT assets be classified as noncurrent on the balance sheet. The FASB decided that the amendments in ASU 2015-17 can be applied either prospectively to all deferred tax liabilities and assets or retrospectively to all periods presented. The update is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2016 and earlier application is permitted. CPG elected early adoption of ASU 2015-17 in December 2015. The December 31, 2016 and 2015 accumulated deferred income taxes are presented with application of ASU 2015-17, and are presented on the Consolidated Balance Sheet as a noncurrent liability. Deferred income taxes result from temporary differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities. The principal components of CPG’s net deferred tax liability were as follows: At December 31, (in millions) 2016 2015 Deferred tax liabilities Accelerated depreciation and other property differences $ 1,625.8 $ 1,429.2 Pension and other postretirement/postemployment benefits 31.1 29.9 Other regulatory assets 67.8 71.8 Equity method investments 130.2 124.3 Total Deferred Tax Liabilities 1,854.9 1,655.2 Deferred tax assets Other regulatory liabilities (104.9 ) (126.8 ) Net operating loss carryforward (231.7 ) (141.4 ) Other (17.9 ) (38.9 ) Total Deferred Tax Assets (354.5 ) (307.1 ) Net Deferred Tax Liabilities $ 1,500.4 $ 1,348.1 State income tax net operating loss benefits for West Virginia were recorded at their full value which CPG anticipates it is more likely than not that it will realize these benefits, prior to their expiration. The $211.5 million Federal net operating loss benefit carryforward will expire in various tax years from 2030 through 2036 and the $20.2 million state net operating loss benefit carryforward will expire in various tax years from 2028 through 2036 . The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate is zero for December 31, 2016 , a $0.4 million decrease for December 31, 2015 and zero for December 31, 2014 . CPG recognizes accrued interest on unrecognized tax benefits, accrued interest on other income tax liabilities, and tax penalties in income tax expense. No material amounts were recorded for the years ended December 31, 2016 , 2015 and 2014 , respectively. CPG is subject to income taxation in the United States and various state jurisdictions, primarily Indiana, West Virginia, Virginia, Pennsylvania, Kentucky, Louisiana, Mississippi, Maryland, Tennessee, New Jersey and New York. CPG was included in NiSource’s consolidated federal return prior to its separation from NiSource on July 1, 2015. Because NiSource is part of the IRS's Large and Mid-Size Business program, each year's federal income tax return is typically audited by the IRS. As of December 31, 2016 , federal income tax years through 2015 for NiSource have been audited and are effectively closed to further assessment. The statute of limitations in each of the state jurisdictions in which CPG operates remain open until the years are settled for federal income tax purposes, at which time amended state income tax returns reflecting all federal income tax adjustments are filed. As of December 31, 2016 , there were no state income tax audits in progress that would have a material impact on the consolidated and combined financial statements. Subsequent to the Merger, CPG is included in the consolidated Federal income tax return filed by US Parent and is a party to a Federal Tax Allocation Agreement with US Parent. The tax allocation agreement 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	12 Months Ended
	Dec. 31, 2016
Pension and Other Postretirement Benefit Expense [Abstract]
Pension and Other Postretirement Benefits Disclosure	Pension and Other Postretirement Benefits CPG provides defined contribution plans and noncontributory defined benefit retirement plans ("the CPG 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 tax-qualified trusts. 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 tax-qualified trusts for the plans in which its employees and retirees participated. As a result, CPG followed multiple employer accounting under the provisions of GAAP. As of July 1, 2015, in connection with the Separation, accrued pension and postretirement benefit obligations for CPG participants and related plan assets were transferred to CPG. CPG continues to follow multiple employer accounting following the Separation. Pension and Other Postretirement Benefit Plans’ Asset Management . CPG employs a total return investment approach whereby a mix of equities and fixed income investments are used to maximize the long-term return of plan assets for a prudent level of risk. Risk tolerance is established through careful consideration of plan liabilities, plan funded status, and asset class volatility. The investment portfolio contains a diversified blend of equity and fixed income investments. Furthermore, equity investments are diversified across U.S. and non-U.S. stocks, as well as growth, value, small and large capitalizations. Derivatives may be used to gain market exposure in an efficient and timely manner; however, derivatives may not be used to leverage the portfolio beyond the market value of the underlying assets. Investment risk is measured and monitored on an ongoing basis through quarterly investment portfolio reviews, annual liability measurements, and periodic asset/liability studies. To establish a long-term rate of return for plan assets assumption, past historical capital market returns and a proprietary forecast are evaluated. The long-term historical relationships between equities and fixed income are analyzed to ensure that they are consistent with the widely accepted capital market principle that assets with higher volatility generate greater return over the long run. Current market factors such as inflation and interest rates are evaluated before long-term capital market assumptions are determined. Peer data and historical returns are reviewed to check for reasonability and appropriateness. The most important component of an investment strategy is the portfolio asset mix, or the allocation between the various classes of securities available to the pension and other postretirement benefit plans for investment purposes. The asset mix and acceptable minimum and maximum ranges established for the CPG plan assets represents a long-term view and are listed in the following table. In 2016, a revised asset allocation policy for the pension fund was approved. This policy calls for a gradual reduction in the allocation to return-seeking assets (equities, private equity and hedge funds) and a corresponding increase in the allocation to liability-hedging assets (fixed income) as the funded status (as measured by the projected benefit obligation of the qualified pension plan divided by the market value of qualified pension plan assets) increases. The asset mix and acceptable minimum and maximum ranges established by the policy for the pension fund at the pension plans funded status on December 31, 2016 are as follows: Asset Mix Policy of Funds: Defined Benefit Pension Plan Postretirement Benefit Plan Asset Category Minimum Maximum Minimum Maximum Domestic Equities 35% 55% 35% 55% International Equities 10% 20% 15% 25% Fixed Income 30% 50% 20% 50% Short-Term Investments 0% 10% 0% 10% Pension Plan and Postretirement Plan Asset Mix at December 31, 2016 and December 31, 2015 : December 31, 2016 Defined Benefit Postretirement Asset Class Asset Value % of Total Assets Asset Value % of Total Assets (in millions) (in millions) Domestic Equities $ 148.7 42.7 % $ 95.9 41.5 % International Equities 56.3 16.2 % 43.4 18.8 % Fixed Income 136.3 39.2 % 76.9 33.2 % Cash/Other 6.8 1.9 % 15.1 6.5 % Total $ 348.1 100.0 % $ 231.3 100.0 % December 31, 2015 Defined Benefit Postretirement Asset Class Asset Value % of Total Assets Asset Value % of Total Assets (in millions) (in millions) Domestic Equities $ 141.0 39.4 % $ 101.6 44.4 % International Equities 62.5 17.5 % 42.8 18.8 % Fixed Income 123.3 34.4 % 76.6 33.6 % Cash/Other 31.0 8.7 % 7.2 3.2 % Total $ 357.8 100.0 % $ 228.2 100.0 % The categorization of investments into the asset classes in the table above are based on definitions established by the CPG Benefits Committee. Fair Value Measurements. The following table sets forth, by level within the fair value hierarchy, the CPG Pension Plan Trust and OPEB investment assets at fair value as of December 31, 2016 and 2015 . Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Total CPG Pension Plan Trust and OPEB investment assets at fair value classified within Level 3 were zero as of December 31, 2016 and December 31, 2015 . Valuation Techniques Used to Determine Fair Value: Level 1 Measurements Most common and preferred stock are traded in active markets on national and international securities exchanges and are valued at closing prices on the last business day of each period presented. Cash is stated at cost which approximates their fair value, with the exception of cash held in foreign currencies which fluctuates with changes in the exchange rates. Government bonds, short-term bills and notes are priced based on quoted market values. Level 2 Measurements Most U.S. Government Agency obligations, mortgage/asset-backed securities, and corporate fixed income securities are generally valued by benchmarking model-derived prices to quoted market prices and trade data for identical or comparable securities. To the extent that quoted prices are not available, fair value is determined based on a valuation model that includes inputs such as interest rate yield curves and credit spreads. Securities traded in markets that are not considered active are valued based on quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. Other fixed income includes futures and options which are priced on bid valuation or settlement pricing. Level 3 Measurements Commingled funds that hold underlying investments that have prices which are not derived from the quoted prices in active markets are classified as Level 3. The respective fair values of these investments are determined by reference to the funds' underlying assets, which are principally marketable equity and fixed income securities. Units held in commingled funds are valued at the unit value as reported by the investment managers. These investments are often valued by investment managers on a periodic basis using pricing models that use market, income, and cost valuation methods. The hedge funds of funds invest in several strategies including fundamental long/short, relative value, and event driven. Hedge fund of fund investments may be redeemed annually, usually with 100 days' notice. Private equity investment strategies include buy-out, venture capital, growth equity, distressed debt, and mezzanine debt. Private equity investments are held through limited partnerships. Limited partnerships are valued at estimated fair market value based on their proportionate share of the partnership's fair value as recorded in the partnerships' audited financial statements. Partnership interests represent ownership interests in private equity funds and real estate funds. Real estate partnerships invest in natural resources, commercial real estate and distressed real estate. The fair value of these investments is determined by reference to the funds' underlying assets, which are principally securities, private businesses, and real estate properties. The value of interests held in limited partnerships, other than securities, is determined by the general partner, based upon third-party appraisals of the underlying assets, which include inputs such as cost, operating results, discounted cash flows and market based comparable data. Private equity and real estate limited partnerships typically call capital over a 3 to 5 year period and pay out distributions as the underlying investments are liquidated. The typical expected life of these limited partnerships is 10-15 years and these investments typically cannot be redeemed prior to liquidation. Net Asset Value Measurements Commingled funds that hold underlying investments that have prices which are derived from the quoted prices in active markets are measure at net asset value. The funds' underlying assets are principally marketable equity and fixed income securities. Units held in commingled funds are valued at the unit value as reported by the investment managers. The fair value of the investments in commingled funds has been estimated using the net asset value per share of the investments. For the year ended December 31, 2016 , there were no significant changes to valuation techniques to determine the fair value of CPG's pension and other postretirement benefits' assets. Fair Value Measurements at December 31, 2016 : Fair Value Measurements (in millions) December 31, Quoted Prices in Active Significant Other Significant Pension plan assets Cash $ 0.2 $ 0.2 $ — $ — Fixed income securities Government 8.8 — 8.8 — Corporate 19.5 — 19.5 — Commingled funds Short-term money markets (2) 6.6 U.S. equities (2) 93.1 International equities (2) 56.3 Fixed income (2) 73.2 Mutual funds U.S. equities 55.6 55.6 — — Fixed income 34.8 34.8 — — Pension plan assets subtotal 348.1 90.6 28.3 — Other postretirement benefit plan assets Cash 0.4 0.4 — — Commingled funds Short-term money markets (2) 14.7 U.S. equities (2) 1.0 Mutual funds U.S. equities 94.9 94.9 — — International equities 43.4 43.4 — — Fixed income 76.9 76.9 — — Other postretirement benefit plan assets subtotal 231.3 215.6 — — Due to brokers, net (1) (0.2 ) Accrued investment income/dividends 0.6 Total pension and other postretirement benefit plan assets $ 579.8 $ 306.2 $ 28.3 $ — (1) This class represents pending trades with brokers. (2) This class of investments is measured at fair value using the net asset value per share and has not been classified in the fair value hierarchy. The table below sets forth a summary of unfunded commitments, redemption frequency and redemption notice periods for certain investments that are measured at fair value using the net asset value per share for the year ended December 31, 2016: (in millions) Fair Value Unfunded Commitments Redemption Frequency Redemption Notice Period Commingled Funds Short-term money markets $ 21.3 $ — Daily 1 day U.S. equities 94.1 — Daily 1 day International equities 56.3 — Daily 2 days Fixed income 73.2 — Daily 2-3 days Total $ 244.9 — Fair Value Measurements at December 31, 2015 : Fair Value Measurements (in millions) December 31, Quoted Prices in Active Significant Other Significant Pension plan assets Cash $ 0.9 $ 0.9 $ — $ — Equity securities International equities 6.6 6.6 — — Fixed income securities Government 8.5 — 8.5 — Corporate 13.0 — 13.0 — Commingled funds Short-term money markets (2) 31.1 U.S. equities (2) 141.0 International equities (2) 55.6 Fixed income (2) 100.9 Pension plan assets subtotal 357.6 7.5 21.5 — Other postretirement benefit plan assets Commingled funds Short-term money markets (2) 7.3 U.S. equities (2) 13.9 Mutual funds U.S. equities 87.7 87.7 — — International equities 42.8 42.8 — — Fixed income 76.5 76.5 — — Other postretirement benefit plan assets subtotal 228.2 207.0 — — Due to brokers, net (1) (0.4 ) Accrued investment income/dividends 0.6 Total pension and other postretirement benefit plan assets $ 586.0 $ 214.5 $ 21.5 $ — (1) This class represents pending trades with brokers. (2) This class of investments is measured at fair value using the net asset value per share and has not been classified in the fair value hierarchy. The table below sets forth a summary of changes in the fair value of the Plan’s Level 3 assets for the year ended December 31, 2015 : (in millions) Balance at January 1, 2015 Total gains or losses (unrealized / realized) Purchases (Sales) Transfers into/(out of) level 3 Separation Allocation (1) Balance at December 31, 2015 Fixed income securities Other fixed income $ 0.1 $ — $ — $ — $ — $ (0.1 ) $ — Private equity limited partnerships U.S. multi-strategy 8.5 — — — — (8.5 ) — International multi-strategy 5.3 — — — — (5.3 ) — Distressed opportunities 1.1 — — — — (1.1 ) — Real estate 2.6 — — — — (2.6 ) — Total $ 17.6 $ — $ — $ — $ — $ (17.6 ) $ — (1) Level 3 assets were not contributed to the CPG Plans upon Separation from NiSource and no subsequent investments were made in Level 3 assets post Separation. The table below sets forth a summary of unfunded commitments, redemption frequency and redemption notice periods for certain investments that are measured at fair value using the net asset value per share for the year ended December 31, 2015: (in millions) Fair Value Unfunded Commitments Redemption Frequency Redemption Notice Period Commingled Funds Short-term money markets $ 38.4 $ — Daily 1 day U.S. equities 154.9 — Monthly 3 days International equities 55.6 — Monthly 14-30 days Fixed income 100.9 — Monthly 3 days Total $ 349.8 $ — Pension and Other Postretirement Benefit Plans’ Funded Status and Related Disclosure . The following table provides a reconciliation of the plans’ funded status and amounts reflected in CPG’s Consolidated Balance Sheets at December 31 based on a December 31 measurement date: Pension Benefits Other Postretirement Benefits (in millions) 2016 2015 2016 2015 Change in projected benefit obligation (1) Benefit obligation at beginning of year $ 404.5 $ 397.6 $ 112.1 $ 124.2 Service cost 6.4 5.9 0.9 1.0 Interest cost 15.1 15.0 4.5 4.7 Plan participants’ contributions — — 2.8 2.3 Actuarial (gain) loss (4.7 ) (6.9 ) 2.1 (12.4 ) Settlement loss 3.2 — — — Benefits paid (48.8 ) (29.7 ) (13.6 ) (9.8 ) Estimated benefits paid by incurred subsidy — — 0.3 0.3 Transfer of participant balances from NiSource plans (2) — 22.6 — 1.8 Projected benefit obligation at end of year $ 375.7 $ 404.5 $ 109.1 $ 112.1 Change in plan assets Fair value of plan assets at beginning of year $ 357.8 $ 351.0 $ 228.2 $ 223.8 Actual return on plan assets 30.7 1.2 13.6 (2.5 ) Employer contributions 8.4 20.0 0.3 13.5 Plan participants’ contributions — — 2.8 2.3 Benefits paid (48.8 ) (29.7 ) (13.6 ) (9.8 ) Transfer of participant balances from NiSource plans (2) — 15.3 — 0.9 Fair value of plan assets at end of year $ 348.1 $ 357.8 $ 231.3 $ 228.2 Funded status at end of year $ (27.6 ) $ (46.7 ) $ 122.2 $ 116.1 Amounts recognized in the balance sheet consist of: Noncurrent assets $ — $ — $ 122.2 $ 116.1 Current liabilities — (0.8 ) — — Noncurrent liabilities (27.6 ) (45.9 ) — — Net amount recognized at end of year (3) $ (27.6 ) $ (46.7 ) $ 122.2 $ 116.1 Amounts recognized in AOCI or regulatory assets/liabilities (4) Unrecognized prior service credit $ (2.6 ) $ (3.7 ) $ (1.3 ) $ (2.0 ) Unrecognized actuarial loss (gain) 133.0 164.5 (0.7 ) (3.9 ) Total recognized AOCI or regulatory assets/liabilities $ 130.4 $ 160.8 $ (2.0 ) $ (5.9 ) (1) The change in benefit obligation for Pension Benefits represents the change in Projected Benefit Obligation while the change in benefit obligation for Other Postretirement Benefits represents the change in Accumulated Postretirement Benefit Obligation. (2) Reflects the transfer of additional pension and OPEB plan participants to CPGSC upon Separation from NiSource that were determined in the current year. (3) CPG recognizes in its Consolidated Balance Sheets the underfunded and overfunded status of its various defined benefit postretirement plans, measured as the difference between the fair value of the plan assets and the benefit obligation. (4) CPG determined that the future recovery of pension and other postretirement benefits costs is probable. CPG recorded regulatory assets and liabilities of $111.3 million and zero , respectively, as of December 31, 2016 , and $135.2 million and $0.7 million , respectively, as of December 31, 2015 that would otherwise have been recorded to accumulated other comprehensive loss. CPG’s accumulated benefit obligation for its pension plans was $375.7 million and $404.5 million as of December 31, 2016 and 2015 , respectively. The accumulated benefit obligation as of a date is the actuarial present value of benefits attributed by the pension benefit formula to employee service rendered prior to that date and based on current and past compensation levels. CPG's pension plans were underfunded by $27.6 million at December 31, 2016 , compared to being underfunded by $46.7 million at December 31, 2015 . The improvement in funded status is primarily due to the return on plan assets. CPG contributed $8.4 million and $20.0 million to its pension plans in 2016 and 2015 , respectively. During 2016 , CPG’s funded status for its other postretirement benefit plans improved by $6.1 million to an overfunded status of $122.2 million primarily due to the return on plan assets, offset by a decrease in the discount rates in 2016 compared to 2015. CPG contributed approximately $0.3 million and $13.5 million to its other postretirement benefit plans in 2016 and 2015 , respectively. No amounts of CPG’s pension or other postretirement benefit plans’ assets are expected to be returned to CPG or any of its subsidiaries in 2017 . In 2016, CPG's pension plans had year to date lump sum payouts exceeding the plans' 2016 service cost plus interest cost due to Merger related payouts as well as the non-qualified pension plan being terminated in connection with the Merger. As a result, settlement accounting was required and CPG recorded a settlement charge of $12.3 million for the year ended December 31, 2016. The following table provides the key assumptions that were used to calculate the pension and other postretirement benefits obligations for CPG’s various plans as of December 31: Pension Benefits Other Postretirement Benefits 2016 2015 2016 2015 Weighted-average assumptions to Determine Benefit Obligation Discount Rate 4.10 % 4.05 % 4.25 % 4.29 % Rate of Compensation Increases 2.50 % 4.00 % Health Care Trend Rates Trend for Next Year 8.47 % 8.39 % Ultimate Trend 4.50 % 4.50 % Year Ultimate Trend Reached 2024 2022 Assumed health care cost trend rates have a significant effect on the amounts reported for the health care plans. A one-percentage-point change in assumed health care cost trend rates would have the following effects: (in millions) 1% point increase 1% point decrease Effect on service and interest components of net periodic cost $ 0.1 $ (0.1 ) Effect on accumulated postretirement benefit obligation 2.6 (2.4 ) CPG expects to make contributions of zero dollars to its pension plan and approximately $1.9 million to its postretirement medical and life plans in 2017 . The following table provides benefits expected to be paid in each of the next five fiscal years, and in the aggregate for the five fiscal years thereafter. The expected benefits are estimated based on the same assumptions used to measure CPG's benefit obligation at the end of the year and includes benefits attributable to the estimated future service of employees: (in millions) Pension Benefits Other Federal Year(s) 2017 $ 32.3 $ 7.8 $ 0.5 2018 33.1 7.8 0.5 2019 33.8 7.8 0.4 2020 35.2 7.7 0.4 2021 34.9 7.6 0.4 2022-2026 168.8 35.5 1.2 The following table provides the components of the plans’ net periodic benefits cost for each of the three years ended December 31, 2016 , 2015 and 2014 : Pension Benefits Other Postretirement Benefits (in millions) 2016 2015 2014 2016 2015 2014 Components of Net Periodic Benefit Cost (Income) Service cost $ 6.4 $ 5.9 $ 4.8 $ 0.9 $ 1.0 $ 1.1 Interest cost 15.1 15.0 15.7 4.5 4.7 4.6 Expected return on assets (25.0 ) (28.2 ) (27.3 ) (15.0 ) (18.1 ) (16.6 ) Amortization of prior service (credit) cost (1.2 ) (1.1 ) (1.1 ) (0.7 ) (0.3 ) 0.1 Recognized actuarial loss (gain) 12.2 9.9 7.5 0.3 (0.3 ) — Net Periodic Benefit Cost (Income) 7.5 1.5 (0.4 ) (10.0 ) (13.0 ) (10.8 ) Additional loss recognized due to: Settlement loss 12.3 — — — — — Total Net Periodic Benefit Cost (Income) $ 19.8 $ 1.5 $ (0.4 ) $ (10.0 ) $ (13.0 ) $ (10.8 ) The $18.3 million increase in the actuarially-determined pension benefit cost (income) is due primarily to the settlement charge and a decrease in the expected return on plan assets in 2016 compared to 2015 . For its other postretirement benefit plans, CPG recognized $10.0 million in net periodic benefit income in 2016 compared to net periodic benefit income of $13.0 million in 2015 due primarily to a decrease in the expected return on plan assets in 2016 compared to 2015 . The following table provides the key assumptions that were used to calculate the net periodic benefits cost for CPG's various plans: Pension Benefits Other Postretirement Benefits 2016 2015 2014 2016 2015 2014 Weighted-average Assumptions to Determine Net Periodic Benefit Cost Discount Rate 3.90 % 3.84 % 4.34 % 4.12 % 4.10 % 4.76 % Expected Long-Term Rate of Return on Plan Assets 7.29 % 8.20 % 8.30 % 6.81 % 8.05 % 8.14 % Rate of Compensation Increases 4.00 % 4.00 % 4.00 % CPG believes it is appropriate to assume an 7.29% and 6.81% rate of return on pension and other postretirement plan assets, respectively, for its calculation of 2016 pension benefits cost. This is primarily based on asset mix and historical rates of return. The following table provides other changes in plan assets and projected benefit obligations recognized in other comprehensive income or regulatory asset or liability: Pension Benefits Other Postretirement Benefits (in millions) 2016 2015 2016 2015 Other changes in plan assets and projected benefit obligations recognized in other comprehensive income or regulatory assets or liabilities Settlements $ (12.3 ) $ — $ — $ — Net actuarial (gain) loss (7.1 ) 25.6 3.5 8.6 Less: amortization of prior service cost 1.2 1.1 0.7 0.3 Less: amortization of net actuarial (gain) loss (12.2 ) (9.9 ) (0.3 ) 0.3 Total recognized in other comprehensive income or regulatory assets or liabilities $ (30.4 ) $ 16.8 $ 3.9 $ 9.2 Amount recognized in net periodic benefit cost and other comprehensive income or regulatory assets or liabilities $ (10.6 ) $ 18.3 $ (6.1 ) $ (3.8 ) Based on a December 31, 2016 measurement date, the net unrecognized actuarial (gain) loss, unrecognized prior service cost, and unrecognized transition obligation that will be amortized into net periodic benefit cost during 2017 for the pension plans are $10.0 million , $(1.2) million and zero , respectively, and for other postretirement benefit plans are $0.5 million , $(0.7) million and zero , respectively.

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 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, short-term borrowings and short-term borrowings-affiliated. 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 values of these securities are estimated based on the quoted market prices for similar issues or on the rates offered for securities of the same remaining maturities. These fair value measurements are classified as Level 2 within the fair value hierarchy. For the years ended December 31, 2016 and 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: At December 31, (in millions) Carrying Amount 2016 (1) Estimated Fair Value 2016 Carrying Amount 2015 (1) Estimated Fair Value 2015 Long-term debt $ 2,750.0 $ 2,868.8 $ 2,750.0 $ 2,592.1 (1) The carrying amount of the Notes differs from the Long-term debt balance on the Consolidated Balance Sheets 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	12 Months Ended
	Dec. 31, 2016
Share-based Compensation [Abstract]
Share-Based Compensation	Share-Based Compensation Prior to the Separation, CPG employees participated in NiSource's Omnibus Incentive Plan (the "NiSource Plan") and had outstanding awards under the NiSource Director Stock Incentive Plan (“NiSource Director Plan”), which was terminated in 2010. Upon the Separation, outstanding CPG employee restricted stock units, performance units and employee director awards previously issued under the NiSource Plan and NiSource Director Plan were adjusted and converted into new CPG share-based awards under the Columbia Pipeline Group, Inc. 2015 Omnibus Incentive Plan (the "Omnibus Plan") using a formula designed to preserve the intrinsic value and fair value of the awards immediately prior to the Separation. The performance targets applicable to the performance units were frozen at the levels achieved as of the Separation and pro-rated to reflect the proportion of the service period completed. Under the Omnibus Plan, these awards represent restricted stock units with no performance contingencies. All adjusted awards retained the vesting schedule of the original awards. The Omnibus Plan term began on the effective date of the Separation. The Omnibus Plan provided for awards to employees and non-employee directors of incentive and nonqualified stock options, stock appreciation rights, restricted stock and restricted stock units, performance shares, performance units, cash-based awards and other stock-based awards. 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 $65.2 million , $7.9 million and $4.4 million , during the years ended December 31, 2016 , 2015 and 2014 , respectively, as well as related tax benefits of $21.9 million , $2.9 million and $1.6 million , respectively. Restricted Stock Units and Restricted Stock . In 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 , based on the average market price of CPG's common stock at the date of each grant less the present value of any dividends not received during the vesting period, which will be expensed, net of forfeitures, over the vesting period which is generally three years. There are no restricted stock units or shares of restricted stock outstanding for the 2016 award following the effective time of the Merger. In 2015, CPG granted 130,160 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 $3.6 million , based on the average market price of CPG’s common stock at the date of each grant less the present value of any dividends not received during the vesting period, which will be expensed, net of forfeitures, over the vesting period which is generally three years. There are no restricted stock units or shares of restricted stock outstanding for the 2015 award following the effective time of the Merger. In 2015, NiSource granted restricted stock units and shares of restricted stock that were converted into 450,107 CPG restricted stock units at Separation, subject to service conditions. The total grant date fair value of the shares of restricted stock units and shares of restricted stock was $11.6 million , based on the average market price of NiSource’s common stock at the date of each grant less the present value of any dividends not received during the vesting period converted into CPG common stock awards, which will be expensed, net of forfeitures, over the vesting period which is generally three years. There are no restricted stock units or shares of restricted stock outstanding for the 2015 NiSource award following the effective time of the Merger. In 2014, NiSource granted restricted stock units and shares of restricted stock that were converted into 198,532 CPG restricted stock units at Separation, subject to service conditions. The total grant date fair value of the restricted stock units and shares of restricted stock was $4.2 million , based on the average market price of NiSource’s common stock at the date of each grant less the present value of dividends not received during the vesting period converted into CPG common stock awards, which will be expensed, net of forfeitures, over the vesting period which is generally three years. There are no restricted stock units or shares of restricted stock outstanding for the 2014 NiSource award following the effective time of the Merger. Restricted Stock Units Weighted Average Grant Date Fair Value Nonvested at December 31, 2015 2,268,792 $ 18.85 Granted 12,144 16.86 Forfeited (22,590 ) 22.71 Vested (2,258,346 ) 18.80 Outstanding at December 31, 2016 — $ — Performance Shares . In 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 , based on the average market price of CPG's common stock at the date of grant less the present value of dividends not received during the vesting period which will be expensed, net of forfeitures, over the three year requisite service period. There are no performance shares outstanding for the 2016 award following the effective time of the Merger. In 2015, CPG granted 161,504 performance shares subject to performance and service conditions. The grant date fair value of the awards was $4.5 million , based on the average market price of CPG’s common stock at the date of the grant less the present value of dividends not received during the vesting period which will be expensed, net of forfeitures, over the three year requisite service period. There are no performance shares outstanding for the 2015 award following the effective time of the Merger. In 2014, NiSource granted performance shares that were converted to 586,219 CPG restricted stock units at Separation, subject to performance and service conditions. The grant date fair value of the awards was $11.3 million , based on the average market price of NiSource’s common stock at the date of each grant less the present value of dividends not received during the vesting period which will be expensed, net of forfeitures, over the three year requisite service period. Through the conversion, the performance contingencies were removed from these awards. There are no restricted stock units or shares of restricted stock outstanding for the 2014 NiSource award following the effective time of the Merger. Contingent Awards Weighted Average Grant Date Fair Value Nonvested at December 31, 2015 161,504 $ 28.16 Granted 955,848 17.79 Forfeited — — Vested (1,117,352 ) 19.29 Outstanding at December 31, 2016 — $ — 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 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 years ended December 31, 2016 , 2015 and 2014 , CPG recognized 401(k) match, profit sharing and non-elective contribution expense of $12.2 million , $9.8 million and $8.4 million , respectively.

Other Commitments and Contingen

Other Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Other Commitments and Contingencies	Other Commitments and Contingencies A. Guarantees and Indemnities. In the normal course of 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 December 31, 2016 and the years in which they expire were: (in millions) Total 2017 2018 2019 2020 2021 After Other guarantees $ 4.7 $ 2.2 $ — $ — $ — $ — $ 2.5 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. 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 (the "Program") had a Progra m 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. CPG maintains a $1,000.0 million revolving credit facility. CPG expects that the revolving credit facility will be utilized for the financing of capital expenditures and for CPG’s general corporate purposes, including working capital. As of December 31, 2016, CPG had no outstanding borrowings under the revolving credit facility. Other Guarantees or Obligations. CPG has purchase and sale agreement guarantees totaling $4.7 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 Consolidated Balance Sheets. 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. 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 consolidated financial statements. B. Tax Matters . CPG records liabilities for potential income tax assessments. The accruals relate to tax positions in a variety of taxing jurisdictions and are based on CPG’s estimate of the ultimate resolution of these positions. These liabilities may be affected by changing interpretations of laws, rulings by tax authorities, or the expiration of the statute of limitations. CPG was included in NiSource's consolidated federal return for tax years prior to December 31, 2014 and will be included in NiSource's consolidated 2015 federal return through July 1, 2015. NiSource is part of the IRS Large and Mid-Size Business program. As a result, each year’s federal income tax return is typically audited by the IRS. As of December 31, 2016, federal income tax years through 2015 for NiSource have been audited and are effectively closed to further assessment. The statute of limitations in each of the state jurisdictions in which CPG operates remain open until the years are settled for federal income tax purposes, at which time amended state income tax returns reflecting all federal income tax adjustments are filed. As of December 31, 2016, there were no state income tax audits in progress that would have a material impact on the consolidated and combined financial statements. CPG is currently being audited for sales and use tax compliance in the state of Ohio and West Virginia. None of these sales and use tax audits are expected to have a material impact on the consolidated and combined financial statements. C. Environmental Matters . CPG’s operations are subject to environmental statutes and regulations related to air quality, water quality, hazardous waste and nonhazardous waste. Historically, CPG’s environmental compliance costs have not had a material adverse effect on its results of operations but there can be no assurance that such costs will not be material in the future or that such future compliance with existing, amended or new legal requirements will not have a material adverse effect on CPG’s business and operating results. 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 December 31, 2016 and 2015 , CPG has liabilities recorded of approximately $7.8 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 Consolidated Balance Sheets. The noncurrent portion is included in “Other noncurrent liabilities” in the Consolidated Balance Sheets. 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. Climate Change. The EPA has already promulgated regulations requiring the monitoring and reporting of GHG emissions from, among other sources, certain onshore natural gas transmission and storage facilities, including gathering and boosting facilities, completions and workovers of oil wells with hydraulic fracturing, and blowdowns of natural gas transmission pipelines between compressor stations, in the United States on an annual basis. In August 2016, the EPA proposed a rule revising provisions of the Prevention of Significant Deterioration ("PSD") and Title V Permitting Regulations to conform with the U.S. Supreme Court’s decision in UARG v. EPA, 134 S. Ct. 2427 (2014), and the amended judgment issued by the D.C. Circuit, in Coalition for Responsible Regulation v. EPA, Nos. 09-1322, 10-073, 10-1092 and 10-1167 (D.C. Cir. April 10, 2015). For instance, the August 2016 proposed rule seeks to ensure that neither the PSD nor the Title V rules require a source to obtain a permit solely because the source emits or has the potential to emit ("PTE") GHGs above the applicable regulatory thresholds. In addition, EPA is also proposing under the rulemaking a significant emissions rate ("SER") of 75,000 tons per year carbon dioxide equivalent for GHGs under the PSD program that would establish an appropriate threshold level below which Best Available Control Technology ("BACT") is not required for a source’s GHG emissions. Future legislative and regulatory programs could significantly restrict emissions of greenhouse gases including methane. New Source Performance Standards : In August 2015, the EPA proposed to regulate fugitive methane emissions for compressor stations in the natural gas transmission and storage sector. The proposed rule was subsequently published in the Federal Register on September 18, 2015. In May 2016, the EPA finalized the rule to regulate fugitive methane emissions 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 the delay of repair criteria in the Final Rule and to clarify ambiguities within the rule. Currently, CPG's facilit ies are not impacted by this rule. New or modified sources installed in subsequent years will be impacted by this rule at a cost of approximately $30,000 /site/year. Based on the current capital project schedule, 16 new or modified facilities will be impacted by this rule in 2019 at a total estimated cost of $500,000 annually thereafter. Environmental Remediation CPG has liabilities associated with the cleanup of some of its former operations. Four sites are associated with its former propane operations and ten sites associated with former petroleum operations. The total liability related to these sites was $6.3 million and $6.5 million at December 31, 2016 and 2015 , respectively. The liability represents CPG’s best estimate of the cost to remediate the facilities. CPG has liabilities associated with the PCB remediation of its existing facilities. The total liability related to these sites was $1.5 million and $1.8 million at December 31, 2016 and 2015 , respectively. The liability represents CPG's best estimate of the cost to remediate the facilities. Pipeline Safety In March 2016, the 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 the 2016 Pipeline Safety Act. Extending PHMSA’s statutory mandate through 2019, the 2016 Pipeline Safety Act establishes or continues the development of stringent requirements affecting pipeline safety. CPG will continue to monitor this matter and cannot estimate the impact of these rules at this time. PHMSA issued interim regulations in October 2016 to implement the agency's expanded authority to address unsafe natural gas and hazardous liquid pipeline conditions or practices that pose an imminent hazard to life, property, or the environment. This 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. D. Operating Lease Commitments. CPG leases assets in several areas of its operations. Payments made in connection with operating leases were $23.9 million in 2016 , $21.2 million in 2015 and $14.9 million in 2014 , and are primarily charged to operation and maintenance expense as incurred. Future minimum rental payments required under operating and capital leases that have initial or remaining non-cancelable lease terms in excess of one year are: (in millions) Operating Leases (1) 2017 $ 8.7 2018 7.4 2019 6.6 2020 6.3 2021 5.5 After 23.5 Total future minimum payments $ 58.0 (1) Operating lease expense includes amounts for fleet leases and storage well leases that can be renewed beyond the initial lease term, but the anticipated payments associated with the renewals do not meet the definition of expected minimum lease payments and, therefore, are not included above. E. Service Obligations . CPG has entered into various service agreements whereby CPG is contractually obligated to make certain minimum payments in future periods. CPG has pipeline service agreements that provide for pipeline capacity, transportation and storage services. These agreements, which have expiration dates ranging from 2017 to 2031, require CPG to pay fixed monthly charges. On June 15, 2015 , CPG entered into a five-year IT services agreement including cloud, mobile, analytics and security technologies with IBM. The agreement became effective with the closing of the Separation on July 1, 2015 , with tiered commencement dates by service line. Under the agreement, at December 31, 2016, CPG expects to pay approximately $128.2 million to IBM in service fees as shown in the table below. Upon any termination of the agreement by CPG for any reason (other than material breach by IBM), CPG may be required to pay IBM a termination charge that could include a breakage fee, repayment of IBM's capital investments not yet recovered and IBM's wind-down expense. This termination fee could be material depending on the events giving rise to the termination and the timing of the termination. The estimated aggregate amounts of minimum fixed payments at December 31, 2016 , were: (in millions) Pipeline Service Agreements IBM Service Agreement 2017 $ 67.0 $ 34.3 2018 63.4 31.8 2019 55.9 31.2 2020 38.4 30.9 2021 32.2 — After 187.0 — Total future minimum payments $ 443.9 $ 128.2

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Dec. 31, 2016
Components of Accumulated Other Comprehensive Income (Loss) [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The following table displays the activity of Accumulated Other Comprehensive Loss, net of tax: (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, 2014 - Predecessor $ (17.6 ) $ (8.2 ) $ (25.8 ) Other comprehensive income before reclassifications — (9.3 ) (9.3 ) Amounts reclassified from accumulated other comprehensive income 1.0 (0.4 ) 0.6 Net current-period other comprehensive income 1.0 (9.7 ) (8.7 ) Balance as of December 31, 2014 $ (16.6 ) $ (17.9 ) $ (34.5 ) Other comprehensive income before reclassifications (0.9 ) 5.0 4.1 Amounts reclassified from accumulated other comprehensive income (2) 1.1 0.2 1.3 Net current-period other comprehensive income 0.2 5.2 5.4 Allocation of accumulated other comprehensive loss to noncontrolling interest 2.1 — 2.1 Balance as of December 31, 2015 $ (14.3 ) $ (12.7 ) $ (27.0 ) Other comprehensive income before reclassifications — 3.7 3.7 Amounts reclassified from accumulated other comprehensive income (2) 1.3 (1.7 ) (0.4 ) Net current-period other comprehensive income 1.3 2.0 3.3 Allocation of accumulated other comprehensive loss to noncontrolling interest 0.2 — 0.2 Balance as of December 31, 2016 $ (13.2 ) $ (10.7 ) $ (23.9 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits. (2) Includes amounts allocated to noncontrolling interest. Equity Method Investment During 2008, Millennium Pipeline, in which CPG has an equity investment, entered into three interest rate swap agreements with a notional amount totaling $420.0 million with seven counterparties. During August 2010, Millennium Pipeline completed the refinancing of its long-term debt, securing permanent fixed-rate financing through the private placement issuance of two tranches of notes totaling $725.0 million , $375.0 million at 5.33% due June 30, 2027 and $350.0 million at 6.00% due June 30, 2032 . Upon the issuance of these notes, Millennium Pipeline repaid all outstanding borrowings under its credit agreement, terminated the sponsor guarantee, and cash settled the interest rate hedges. These interest rate swap derivatives were primarily accounted for as cash flow hedges by Millennium Pipeline. As an equity method investment, CPG is required to recognize a proportional share of Millennium Pipeline’s OCI. The remaining unrecognized loss of $13.2 million , net of tax, related to these 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 $13.2 million and $14.3 million at December 31, 2016 and December 31, 2015 , respectively, is included in unrealized losses on cash flow hedges above.

Other, Net

Other, Net	12 Months Ended
	Dec. 31, 2016
Other Nonoperating Income (Expense) [Abstract]
Other, Net	Other, Net Year Ended December 31, (in millions) 2016 2015 2014 AFUDC Equity $ 34.9 $ 28.3 $ 11.0 Miscellaneous 0.2 1.0 (2.2 ) Total Other, net $ 35.1 $ 29.3 $ 8.8

Interest Expense

Interest Expense	12 Months Ended
	Dec. 31, 2016
Interest Expense [Abstract]
Interest Expense	Interest Expense Year Ended December 31, (in millions) 2016 2015 2014 Interest on long-term debt $ 111.0 $ 67.5 $ — Interest on short-term borrowings 0.2 1.4 — Debt discount/cost amortization (1) 10.2 3.1 — Allowance for funds used during construction (5.1 ) (6.8 ) — Other 2.8 2.4 — Total Interest Expense (2) $ 119.1 $ 67.6 $ — (1) Debt discount/cost amortization for 2016 primarily consists of the accelerated amortization of $5.7 million of deferred costs associated with the CPG and CPPL revolving credit facilities. Refer to Note 5, "Short-term Borrowings" for additional information regarding the early termination of the revolving credit facilities. (2) Refer to Note 4, "Transactions with Affiliates" for a discussion of interest expense-affiliated for the year ended December 31, 2016 , 2015 and 2014 .

Segments of Business

Segments of Business	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Segments of Business	Segments of Business Operating segments are components of an enterprise for which separate financial information is available and evaluated regularly by the chief operating decision maker in deciding how to allocate resources and assess performance. As of December 31, 2016, TransCanada's Executive Vice President and President, Natural Gas Pipelines is the chief operating decision maker. At December 31, 2016 , CPG's operations comprise one operating segment. CPG's segment offers gas transportation and storage services for LDCs, marketers and industrial and commercial customers located in northeastern, mid-Atlantic, Midwestern and southern states and the District of Columbia along with unregulated businesses that include midstream services and development of mineral rights positions. The chief operating decision maker evaluates the performance of CPG operations and determines how to allocate resources on a consolidated basis.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2016
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information The following tables provide additional information regarding the CPG’s Statements of Consolidated and Combined Cash Flows for the years ended December 31, 2016 , 2015 and 2014 : Year Ended December 31, (in millions) 2016 2015 2014 Supplemental Disclosures of Cash Flow Information Non-cash transactions: Capital expenditures included in current liabilities (1) $ 146.1 $ 128.4 $ 78.5 Schedule of interest and income taxes paid: Cash paid for interest, net of interest capitalized amounts $ 111.1 $ 96.9 $ 53.6 Cash paid for income taxes (2) 4.1 32.3 21.2 (1) Capital expenditures included in current liabilities is comprised of "Accrued capital expenditures" and certain other amounts included within "Accounts payable" on the Consolidated Balance Sheets. (2) Cash paid for income taxes for the year ended December 31, 2015 includes $20.9 million paid to NiSource under the Tax Allocation Agreement.

Concentration of Credit Risk

Concentration of Credit Risk	12 Months Ended
	Dec. 31, 2016
Risks and Uncertainties [Abstract]
Concentration of Credit Risk	Concentration of Credit Risk Columbia Gas of Ohio, an affiliated party prior to the Separation, accounted for greater than 10% of total operating revenues in the years ended December 31, 2016 , 2015 and 2014 . The following table provides this customer's operating revenues and percentage of total operating revenues for the years ended December 31, 2016 , 2015 and 2014 : Year Ended December 31, 2016 2015 2014 (in millions) Total Operating Revenues Percentage of Total Operating Revenues Total Operating Revenues Percentage of Total Operating Revenues Total Operating Revenues Percentage of Total Operating Revenues Columbia Gas of Ohio (1) $ 169.7 12.3 % $ 167.3 12.5 % $ 168.5 12.5 % (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 agreements 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 would have a material adverse effect on the business of CPG.

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Quarterly Financial Data (Unaudited)	Quarterly Financial Data (Unaudited) (in millions) First Quarter Second Quarter Third Quarter Fourth Quarter 2016 Total Operating Revenues $ 364.5 $ 313.9 $ 327.1 $ 376.5 Operating Income (Loss) 151.7 91.5 (53.0 ) 127.4 Income (Loss) from Continuing Operations 86.6 48.6 (49.6 ) 68.1 Results from Discontinued Operations - net of taxes 0.2 — — — Net Income (Loss) Attributable to CPG 72.2 38.9 (52.5 ) 58.2 2015 Total Operating Revenues $ 340.0 $ 316.1 $ 320.9 $ 357.9 Operating Income 162.7 107.3 135.9 122.2 Income from Continuing Operations 97.1 60.1 74.9 75.4 Results from Discontinued Operations - net of taxes — (0.3 ) (0.1 ) — Net Income Attributable to CPG 90.0 50.8 63.0 63.4

Condensed Consolidating Financi

Condensed Consolidating Financial Statements	12 Months Ended
	Dec. 31, 2016
Guarantees [Abstract]
Condensed Consolidating Financial Statements	Condensed Consolidating Financial Statements 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 6, "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 December 31, 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 $ 38.8 $ 30.0 $ — $ — $ 11.1 $ — $ 79.9 Accounts receivable, net — 0.1 — — 194.1 — 194.2 Accounts receivable-affiliated 799.6 579.5 — — 190.0 (1,513.3 ) 55.8 Materials and supplies, at average cost — — — — 26.0 — 26.0 Exchange gas receivable — — — — 27.7 — 27.7 Deferred property taxes — — — — 61.2 — 61.2 Taxes receivable 68.6 43.6 — — — (112.2 ) — Prepayments and other 0.3 0.4 — — 28.2 — 28.9 Total Current Assets 907.3 653.6 — — 538.3 (1,625.5 ) 473.7 Investments Unconsolidated affiliates — — — — 446.7 — 446.7 Consolidated affiliates 5,421.1 7,482.0 6,089.2 — — (18,992.3 ) — Other investments — — — — 0.8 — 0.8 Total Investments 5,421.1 7,482.0 6,089.2 — 447.5 (18,992.3 ) 447.5 Property, Plant and Equipment Property, plant and equipment — — — — 10,461.2 — 10,461.2 Accumulated depreciation and amortization — — — — (3,126.2 ) — (3,126.2 ) Net Property, Plant and Equipment — — — — 7,335.0 — 7,335.0 Other Noncurrent Assets Regulatory assets — 56.5 — — 116.4 — 172.9 Goodwill — — 1,975.5 — — — 1,975.5 Notes receivable-affiliated 1,848.2 — — — — (1,848.2 ) — Postretirement and postemployment benefits assets — 0.8 — — 121.4 (0.4 ) 121.8 Deferred income taxes — — — — 84.8 (84.8 ) — Deferred charges and other 1.7 — — — 9.6 — 11.3 Total Other Noncurrent Assets 1,849.9 57.3 1,975.5 — 332.2 (1,933.4 ) 2,281.5 Total Assets $ 8,178.3 $ 8,192.9 $ 8,064.7 $ — $ 8,653.0 $ (22,551.2 ) $ 10,537.7 CONDENSED CONSOLIDATING BALANCE SHEETS (continued) As of December 31, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated LIABILITIES, TEMPORARY EQUITY AND EQUITY Current Liabilities Short-term borrowings-affiliated $ — $ — $ 570.8 $ — $ 923.6 $ (1,494.4 ) $ — Accounts payable — 0.6 — — 69.8 — 70.4 Accounts payable-affiliated 7.0 5.1 0.8 — 10.0 (18.9 ) 4.0 Customer deposits — — — — 17.3 — 17.3 Taxes accrued — — — — 229.1 (112.2 ) 116.9 Interest accrued 9.3 — — — 0.1 — 9.4 Exchange gas payable — — — — 27.2 — 27.2 Deferred revenue — — — — 3.9 — 3.9 Accrued capital expenditures — — — — 111.4 — 111.4 Accrued compensation and related costs — — — — 62.3 — 62.3 Other accruals 0.1 0.5 — — 109.5 — 110.1 Total Current Liabilities 16.4 6.2 571.6 — 1,564.2 (1,625.5 ) 532.9 Noncurrent Liabilities Long-term debt 2,728.6 — — — — — 2,728.6 Long-term debt-affiliated — 1,217.3 — — 630.9 (1,848.2 ) — Deferred income taxes 42.8 1,542.4 — — — (84.8 ) 1,500.4 Accrued liability for postretirement and postemployment benefits 0.7 6.4 — — 25.5 (0.4 ) 32.2 Regulatory liabilities — 10.2 — — 263.4 — 273.6 Asset retirement obligations — — — — 20.8 — 20.8 Other noncurrent liabilities 0.4 1.8 — — 57.6 — 59.8 Total Noncurrent Liabilities 2,772.5 2,778.1 — — 998.2 (1,933.4 ) 4,615.4 Total Liabilities 2,788.9 2,784.3 571.6 — 2,562.4 (3,558.9 ) 5,148.3 Temporary Equity Redeemable noncontrolling interest 952.9 952.9 — — — (952.9 ) 952.9 Equity Common stock 0.1 — — — — — 0.1 Additional paid-in capital 4,513.8 — — — — — 4,513.8 Accumulated deficit (53.5 ) — — — (53.5 ) Net parent investment — 4,479.3 7,516.2 — 6,117.5 (18,113.0 ) — Accumulated other comprehensive loss (23.9 ) (23.6 ) (23.1 ) — (26.9 ) 73.6 (23.9 ) Total Equity 4,436.5 4,455.7 7,493.1 — 6,090.6 (18,039.4 ) 4,436.5 Total Liabilities, Temporary Equity and Equity $ 8,178.3 $ 8,192.9 $ 8,064.7 $ — $ 8,653.0 $ (22,551.2 ) $ 10,537.7 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 Year Ended December 31, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 1,155.1 $ — $ 1,155.1 Storage revenues — — — — 196.5 — 196.5 Other revenues — — — — 30.4 — 30.4 Total Operating Revenues — — — — 1,382.0 — 1,382.0 Operating Expenses Operation and maintenance 146.6 0.8 — — 716.0 (0.2 ) 863.2 Operation and maintenance-affiliated 3.7 — — — — (3.7 ) — Depreciation and amortization — 0.7 — — 172.1 — 172.8 Gain on sale of assets — — — — (16.6 ) — (16.6 ) Impairment of long-lived assets — — — — 26.1 — 26.1 Property and other taxes 0.1 1.4 0.1 — 81.6 — 83.2 Total Operating Expenses 150.4 2.9 0.1 — 979.2 (3.9 ) 1,128.7 Equity Earnings in Unconsolidated Affiliates — — — — 64.3 — 64.3 Equity Earnings in Consolidated Affiliates 284.0 465.2 477.9 — — (1,227.1 ) — Operating Income 133.6 462.3 477.8 — 467.1 (1,223.2 ) 317.6 Other Income (Deductions) Interest expense (121.0 ) — — — (3.2 ) 5.1 (119.1 ) Interest expense-affiliated (2.1 ) (45.0 ) (3.7 ) — (31.6 ) 80.3 (2.1 ) Other, net 81.1 4.6 — — 34.8 (85.4 ) 35.1 Total Other Deductions, net (42.0 ) (40.4 ) (3.7 ) — — — (86.1 ) Income from Continuing Operations before Income Taxes 91.6 421.9 474.1 — 467.1 (1,223.2 ) 231.5 Income Taxes (62.1 ) 137.8 — — 2.1 — 77.8 Income from Continuing Operations 153.7 284.1 474.1 — 465.0 (1,223.2 ) 153.7 Income from Discontinued Operations-net of taxes 0.2 0.2 — — — (0.2 ) 0.2 Net Income 153.9 284.3 474.1 — 465.0 (1,223.4 ) 153.9 Less: Net income attributable to noncontrolling interest 37.1 37.1 — — — (37.1 ) 37.1 Net Income Attributable to CPG $ 116.8 $ 247.2 $ 474.1 $ — $ 465.0 $ (1,186.3 ) $ 116.8 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (continued) Year Ended December 31, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 1,054.4 $ — $ 1,054.4 Transportation revenues-affiliated — — — — 47.5 — 47.5 Storage revenues — — — — 171.4 — 171.4 Storage revenues-affiliated — — — — 26.2 — 26.2 Other revenues — — — — 35.4 — 35.4 Total Operating Revenues — — — — 1,334.9 — 1,334.9 Operating Expenses Operation and maintenance 20.5 (1.2 ) — — 632.8 — 652.1 Operation and maintenance-affiliated 2.2 0.4 — — 52.5 (2.2 ) 52.9 Depreciation and amortization — — — — 139.9 — 139.9 Gain on sale of assets — — — — (55.3 ) — (55.3 ) Impairment of long-lived assets — 1.8 — — 0.6 — 2.4 Property and other taxes — — — — 75.3 — 75.3 Total Operating Expenses 22.7 1.0 — — 845.8 (2.2 ) 867.3 Equity Earnings in Unconsolidated Affiliates — — — — 60.5 — 60.5 Equity Earnings in Consolidated Affiliates 341.2 529.4 529.6 — — (1,400.2 ) — Operating Income 318.5 528.4 529.6 — 549.6 (1,398.0 ) 528.1 Other Income (Deductions) Interest expense (73.0 ) — — — (1.5 ) 6.9 (67.6 ) Interest expense-affiliated (2.5 ) (40.8 ) — — (26.8 ) 40.8 (29.3 ) Other, net 45.4 0.5 3.5 — 27.6 (47.7 ) 29.3 Total Other Deductions, net (30.1 ) (40.3 ) 3.5 — (0.7 ) — (67.6 ) Income from Continuing Operations before Income Taxes 288.4 488.1 533.1 — 548.9 (1,398.0 ) 460.5 Income Taxes (19.1 ) 146.6 — — 25.5 — 153.0 Income from Continuing Operations 307.5 341.5 533.1 — 523.4 (1,398.0 ) 307.5 Loss from Discontinued Operations-net of taxes (0.4 ) (0.4 ) — — — 0.4 (0.4 ) Net Income 307.1 341.1 533.1 — 523.4 (1,397.6 ) 307.1 Less: Net income attributable to noncontrolling interest 39.9 39.9 — — — (39.9 ) 39.9 Net Income Attributable to CPG $ 267.2 $ 301.2 $ 533.1 $ — $ 523.4 $ (1,357.7 ) $ 267.2 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (continued) Year Ended December 31, 2014 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 990.8 $ — $ 990.8 Transportation revenues-affiliated — — — — 95.7 — 95.7 Storage revenues — — — — 144.0 — 144.0 Storage revenues-affiliated — — — — 53.2 — 53.2 Other revenues — — — — 64.3 — 64.3 Total Operating Revenues — — — — 1,348.0 — 1,348.0 Operating Expenses Operation and maintenance — (2.6 ) — — 631.0 — 628.4 Operation and maintenance-affiliated — 0.5 — — 122.7 — 123.2 Depreciation and amortization — — — — 118.8 — 118.8 Gain on sale of assets — — — — (34.5 ) — (34.5 ) Property and other taxes — — — — 67.1 — 67.1 Total Operating Expenses — (2.1 ) — — 905.1 — 903.0 Equity Earnings in Unconsolidated Affiliates — — — — 46.6 — 46.6 Equity Earnings in Consolidated Affiliates 268.7 269.6 — — — (538.3 ) — Operating Income 268.7 271.7 — — 489.5 (538.3 ) 491.6 Other Income (Deductions) Interest expense-affiliated — — — — (62.0 ) — (62.0 ) Other, net — (0.1 ) — — 8.9 — 8.8 Total Other Deductions, net — (0.1 ) — — (53.1 ) — (53.2 ) Income from Continuing Operations before Income Taxes 268.7 271.6 — — 436.4 (538.3 ) 438.4 Income Taxes — 2.9 — — 166.8 — 169.7 Income from Continuing Operations 268.7 268.7 — — 269.6 (538.3 ) 268.7 Loss from Discontinued Operations-net of taxes (0.6 ) (0.6 ) — — — 0.6 (0.6 ) Net Income $ 268.1 $ 268.1 $ — $ — $ 269.6 $ (537.7 ) $ 268.1 CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Year Ended December 31, 2016 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Income $ 153.9 $ 284.3 $ 474.1 $ — $ 465.0 $ (1,223.4 ) $ 153.9 Other comprehensive income Net unrealized gain (loss) on cash flow hedges 1.3 (0.8 ) — — 2.1 (1.3 ) 1.3 Unrecognized pension and OPEB benefit 2.0 1.7 — — 0.3 (2.0 ) 2.0 Total other comprehensive income 3.3 0.9 — — 2.4 (3.3 ) 3.3 Total Comprehensive Income 157.2 285.2 474.1 — 467.4 (1,226.7 ) 157.2 Less: Comprehensive Income-noncontrolling interest 37.3 37.3 — — — (37.3 ) 37.3 Comprehensive Income-controlling interests $ 119.9 $ 247.9 $ 474.1 $ — $ 467.4 $ (1,189.4 ) $ 119.9 Year Ended December 31, 2015 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Income $ 307.1 $ 341.1 $ 533.1 $ — $ 523.4 $ (1,397.6 ) $ 307.1 Other comprehensive income Net unrealized gain (loss) on cash flow hedges 0.2 (1.6 ) — — 1.8 (0.2 ) 0.2 Unrecognized pension and OPEB benefit 5.2 5.4 — — (0.2 ) (5.2 ) 5.2 Total other comprehensive income 5.4 3.8 — — 1.6 (5.4 ) 5.4 Total Comprehensive Income 312.5 344.9 533.1 — 525.0 (1,403.0 ) 312.5 Less: Comprehensive Income-noncontrolling interest 40.0 40.0 — — — (40.0 ) 40.0 Comprehensive Income-controlling interests $ 272.5 $ 304.9 $ 533.1 $ — $ 525.0 $ (1,363.0 ) $ 272.5 Year Ended December 31, 2014 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Income $ 268.1 $ 268.1 $ — $ — $ 269.6 $ (537.7 ) $ 268.1 Other comprehensive income Net unrealized gain (loss) on cash flow hedges 1.0 — — — 1.0 (1.0 ) 1.0 Unrecognized pension and OPEB cost (9.7 ) (9.7 ) — — — 9.7 (9.7 ) Total other comprehensive income (8.7 ) (9.7 ) — — 1.0 8.7 (8.7 ) Total Comprehensive Income $ 259.4 $ 258.4 $ — $ — $ 270.6 $ (529.0 ) $ 259.4 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Cash Flows from Operating Activities $ (213.6 ) $ 473.7 $ (3.0 ) $ — $ 712.0 $ (608.9 ) $ 360.2 Investing Activities Capital expenditures — — — — (1,438.1 ) — (1,438.1 ) Insurance recoveries — — — — 3.0 — 3.0 Change in short-term lendings-affiliated (736.1 ) (490.4 ) 3.3 — (37.9 ) 1,261.1 — Proceeds from disposition of assets — — — — 10.4 — 10.4 Contributions to equity investees — — — — (6.2 ) — (6.2 ) Distributions from equity investees — — — — 2.2 — 2.2 Other investing activities 10.3 — — — (9.7 ) — 0.6 Net Cash Flows (used for) provided by Investing Activities (725.8 ) (490.4 ) 3.3 — (1,476.3 ) 1,261.1 (1,428.1 ) Financing Activities Change in short-term borrowings — — — — (15.0 ) — (15.0 ) Change in short-term borrowings-affiliated 401.0 — 570.8 — 789.3 (1,261.1 ) 500.0 Payment of short-term borrowings-affiliated (500.0 ) — — — — — (500.0 ) Payment of capital lease obligations and other debt related costs (1.1 ) — — — (4.3 ) — (5.4 ) Issuance of common stock to TransCanada 500.1 — — — — — 500.1 Quarterly distributions to unitholders — — — — (76.9 ) 76.9 — Distribution to noncontrolling interest in Columbia OpCo — — (573.0 ) — — 573.0 — Distribution to noncontrolling interest — — — — — (41.0 ) (41.0 ) Acquisition of treasury stock (6.2 ) — — — — — (6.2 ) Dividends paid - common stock (105.1 ) — — — — — (105.1 ) Dividends paid - TransCanada (110.5 ) — — — — — (110.5 ) Net Cash Flows from (used for) Financing Activities 178.2 — (2.2 ) — 693.1 (652.2 ) 216.9 Change in cash and cash equivalents (761.2 ) (16.7 ) (1.9 ) — (71.2 ) — (851.0 ) 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 $ 38.8 $ 30.0 $ — $ — $ 11.1 $ — $ 79.9 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (continued) Year Ended December 31, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Cash Flows from Operating Activities $ (29.7 ) $ (49.6 ) $ 3.5 $ — $ 589.5 $ (20.2 ) $ 493.5 Investing Activities Capital expenditures — (32.7 ) — — (1,181.0 ) 32.7 (1,181.0 ) Insurance recoveries — — — — 2.1 — 2.1 Change in short-term lendings-affiliated — (83.9 ) (3.3 ) — (0.6 ) 233.3 145.5 Proceeds from disposition of assets — 26.2 — — 84.1 (32.7 ) 77.6 Contributions to equity investees — (1,217.3 ) (446.2 ) — (1.4 ) 1,663.5 (1.4 ) Distributions from equity investees — — — — 16.0 — 16.0 Other investing activities (5.2 ) — — — (22.2 ) — (27.4 ) Net Cash Flows used for Investing Activities (5.2 ) (1,307.7 ) (449.5 ) — (1,103.0 ) 1,896.8 (968.6 ) Financing Activities Change in short-term borrowings — — — — 15.0 — 15.0 Change in short-term borrowings-affiliated 99.0 (5.1 ) — — (113.1 ) (233.3 ) (252.5 ) Issuance of long-term debt 2,745.9 — — — — — 2,745.9 Debt related costs (27.9 ) 6.3 — — (2.0 ) — (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 ) — — — (959.6 ) — (2,807.8 ) Proceeds from the issuance of common units, net of offering costs — — 1,170.0 — (1.6 ) — 1,168.4 Issuance of common stock, net of offering costs 1,394.7 — — — — — 1,394.7 Contribution of capital from parent — — — — 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 — — — — (43.4 ) 43.4 — Distribution to noncontrolling interest in Columbia OpCo — — (187.3 ) — — 187.3 — Distribution received from Columbia OpCo — 187.3 — — — (187.3 ) — Distribution to noncontrolling interest — — — — — (23.2 ) (23.2 ) Dividends paid - common stock (79.5 ) — — — — — (79.5 ) Transfer from NiSource 0.9 (1.8 ) (34.8 ) — 36.5 — 0.8 Net Cash Flows from Financing Activities 834.9 1,404.0 447.9 — 595.3 (1,876.6 ) 1,405.5 Change in cash and cash equivalents 800.0 46.7 1.9 — 81.8 — 930.4 Cash and cash equivalents at beginning of period — — — — 0.5 — 0.5 Cash and Cash Equivalents at End of Period $ 800.0 $ 46.7 $ 1.9 $ — $ 82.3 $ — $ 930.9 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (continued) Year Ended December 31, 2014 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Cash Flows from Operating Activities $ — $ (3.7 ) $ — $ — $ 570.7 $ (2.2 ) $ 564.8 Investing Activities Capital expenditures — — — — (747.2 ) — (747.2 ) Insurance recoveries — — — — 11.3 — 11.3 Change in short-term lendings-affiliated — 4.8 — — (62.0 ) — (57.2 ) Proceeds from disposition of assets — — — — 9.3 — 9.3 Contributions to equity investees — — — — (69.2 ) — (69.2 ) Other investing activities — — — — (7.1 ) — (7.1 ) Net Cash Flows used for Investing Activities — 4.8 — — (864.9 ) — (860.1 ) Financing Activities Change in short-term borrowings-affiliated — 5.2 — — (472.3 ) — (467.1 ) Debt related costs — (6.3 ) — — (0.1 ) — (6.4 ) Issuance of long-term debt-affiliated — — — — 768.9 — 768.9 Distribution to parent — — — — (2.2 ) 2.2 — Net Cash Flows from Financing Activities — (1.1 ) — — 294.3 2.2 295.4 Change in cash and cash equivalents — — — — 0.1 — 0.1 Cash and cash equivalents at beginning of period — — — — 0.4 — 0.4 Cash and Cash Equivalents at End of Period $ — $ — $ — $ — $ 0.5 $ — $ 0.5

Nature of Operations and Summ35

Nature of Operations and Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Company Structure And Principles Of Consolidation	Company Structure and Basis of 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. As a result of this contribution, the financial statements for periods as of and subsequent to September 26, 2014 reflect the consolidated financial position, results of operations and cash flows for CPG. All periods prior to September 26, 2014 reflect the combined financial position, results of operations and cash flows for CPG's Predecessor (the "Predecessor"). 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; • 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 year ended December 31, 2016 , CPG incurred Merger transaction costs of $66.6 million , including legal, advisory and other related fees. These costs are included in "Operation and maintenance" on the Statements of Consolidated and Combined Operations. Approximately $104.9 million of employee related costs were incurred subsequent to the Merger. Additionally as a result of the Merger, CPG recognized an impairment charge of $26.1 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 has also suspended its obligations to file periodic reports with the SEC based on its senior notes and once it has filed its Form 10-K for the year ended December 31, 2016, it will no longer have reporting obligations with respect to its senior notes. Refer to Note 6, "Long-Term Debt" for additional information on CPG's senior notes. CPPL Merger. On November 1, 2016, CPPL announced that it had entered into an agreement and plan of merger ("CPPL Merger Agreement") 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 CPPL Merger Agreement and transactions contemplated by the CPPL Merger Agreement and determined that the CPPL 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 CPPL Merger Agreement and the merger transactions. The GP Board resolved that the CPPL 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 CPPL Merger Agreement and the merger transactions at the special meeting of the unitholders. On February 16, 2017, the CPPL unaffiliated unitholders voted to approve the CPPL Merger. On February 17, 2017, CPG closed the transaction to acquire all outstanding publicly held common units valued at approximately $915 million . CPPL unaffiliated unitholders also received a regular quarterly distribution of $0.1975 per common unit and a pro-rated distribution for the period prior to the closing date. As a result of the CPPL Merger, CPPL became a wholly owned subsidiary of CPG. As of December 31, 2016 and as a result of the CPPL Merger Agreement, CPPL's common units now contain a redemption feature within the control of CPPL's unaffiliated unitholders. The existence of the redemption feature causes CPG's noncontrolling interest to be redeemable at an amount other than fair value, thus requiring CPG to present noncontrolling interest as temporary equity on the Consolidated Balance Sheets. The redeemable noncontrolling interest is recorded at its current book value and will be adjusted each period for net earnings and other comprehensive income attributable to the noncontrolling interest. As of December 31, 2016, CPG did not consider noncontrolling interest to be probable of becoming redeemable given the special meeting of CPPL's unitholders had not yet occurred and there could be no certainty the unaffiliated unitholders will vote to approve the merger. CPG’s accompanying Consolidated and Combined Financial Statements 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 Consolidated and Combined Financial Statements are equity method investments Hardy Storage, Millennium Pipeline and Pennant.
Use Of Estimates	Use of Estimates. The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Cash And Cash Equivalents	Cash and Cash Equivalents. Cash and cash equivalents are liquid marketable securities with an original maturity date of less than three months.
Allowance For Uncollectible Accounts	Allowance for Uncollectible Accounts. The reserve for uncollectible receivables is CPG's best estimate of the amount of probable credit losses in the existing accounts receivable. Collectability of accounts receivable is reviewed regularly and an allowance is established or adjusted, as necessary, using the specific identification method. Account balances are charged against the allowance when it is anticipated the receivable will not be recovered.
Basis Of Accounting For Rate-Regulated Subsidiaries	Basis of Accounting for Rate-Regulated Subsidiaries . Rate-regulated subsidiaries account for and report assets and liabilities consistent with the economic effect of the way in which regulators establish rates, if the rates established are designed to recover the costs of providing the regulated service and it is probable that such rates can be charged and collected. Certain expenses and credits subject to utility regulation or rate determination normally reflected in income are deferred on the Consolidated Balance Sheets and are recognized in income as the related amounts are included in service rates and recovered from or refunded to customers. In the event that regulation significantly changes the opportunity for CPG to recover its costs in the future, all or a portion of CPG’s regulated operations may no longer meet the criteria for regulatory accounting. In such an event, a write-down of all or a portion of CPG’s existing regulatory assets and liabilities could result. If CPG is unable to continue to apply the provisions of regulatory accounting, CPG would be required to apply the provisions of Discontinuation of Rate-Regulated Accounting. In management’s opinion, CPG’s regulated subsidiaries will be subject to regulatory accounting for the foreseeable future. Please see Note 11, "Regulatory Matters," in the Notes to Consolidated and Combined Financial Statements for further discussion.
Property, Plant And Equipment And Related AFUDC and Maintenance	Property, Plant and Equipment and Related AFUDC and Maintenance . Property, plant and equipment is stated at cost. CPG's rate-regulated subsidiaries record depreciation using composite rates on a straight-line basis over the remaining service lives of the properties as approved by the appropriate regulators. CPG's non-regulated companies depreciate assets on a component basis on a straight-line basis over the remaining service lives of the properties. CPG capitalizes AFUDC on all classes of property except organization costs, land, autos, office equipment, tools and other general property purchases. The allowance is applied to construction costs for that period of time between the date of the expenditure and the date on which such project is placed in service. A combination of short-term borrowings, long-term debt and equity were used to fund construction efforts for all three years presented. The pre-tax rate for AFUDC debt and ADUFC equity are summarized in the table below: 2016 2015 2014 Debt Equity Debt Equity Debt Equity Columbia Gas Transmission 0.6 % 4.8 % 1.8 % 6.3 % 0.9 % 3.0 % Columbia Gulf 0.6 % 3.7 % 2.9 % 6.3 % 2.1 % 9.4 % CPG follows the practice of charging maintenance and repairs, including the cost of removal of minor items of property, to expense as incurred. When regulated property that represents a retired unit is replaced or removed, the cost of such property is credited to utility plant, and such cost, net of salvage, is charged to the accumulated provision for depreciation in accordance with composite depreciation.
Gas-Stored Base Gas	Gas Stored-Base Gas. Base gas, which is valued at original cost, represents storage volumes that are maintained to ensure that adequate well pressure exists to deliver current gas inventory. There were no purchases of base gas during the years ended December 31, 2016 , 2015 and 2014 . Gas stored-base gas is included in Property, plant and equipment on the Consolidated Balance Sheets.
Amortization Of Software Costs	Amortization of Software Costs. External and internal costs associated with computer software developed for internal use are capitalized. Capitalization of such costs commences upon the completion of the preliminary stage of each project. Once the installed software is ready for its intended use, such capitalized costs are amortized on a straight-line basis generally over a period of five years. CPG amortized $20.4 million in 2016 , $8.7 million in 2015 and $4.3 million in 2014 related to software costs. CPG’s unamortized software balance was $72.1 million and $59.8 million at December 31, 2016 and 2015 , respectively. The increase in software amortization and unamortized software balance is primarily due to software placed in service subsequent to the Separation. The additional software was necessary for CPG to operate as an independent company.
Goodwill	Goodwill. CPG has $1,975.5 million in goodwill. All goodwill relates to the excess of cost over the fair value of the net assets acquired in the CEG acquisition on November 1, 2000. Please see Note 9, "Goodwill," in the Notes to Consolidated and Combined Financial Statements for further discussion.
Impairments	Impairments. An impairment loss on long-lived assets shall be recognized only if the carrying amount of a long-lived assets is not recoverable and exceeds its fair value. The test for impairment compares the carrying amount of the long-lived asset to the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset. CPG recognized an impairment loss of $26.1 million , $2.4 million and zero for the years ended December 31, 2016 , 2015 and 2014 , respectively. As a result of the Merger, CPG recognized an impairment loss for the year ended December 31, 2016 related to the cancellation of IT system upgrades that were in process prior to the Merger.
Revenue Recognition	Revenue Recognition. Revenue is recorded as services are performed. Revenues are billed to customers monthly at rates established through the FERC's cost-based rate-making process or at rates less than those allowed by the FERC. Revenues are recorded on the accrual basis and include estimates for transportation provided but not billed. The demand and commodity charges for transportation of gas under long-term agreements are recognized separately. Demand revenues are recognized monthly over the term of the agreement with the customer regardless of the volume of natural gas transported. Commodity revenues for both firm and interruptible transportation are recognized in the period the transportation services are provided based on volumes of natural gas physically delivered at the agreed upon delivery point. CPG provides shorter term transportation and storage services for which cash is received at inception of the service period resulting in the recording of deferred revenues that are recognized in revenues over the period the services are provided. Storage capacity revenues are recognized monthly over the term of the agreement with the customer regardless of the volume of storage service actually utilized. Injection and withdrawal revenues are recognized in the period when volumes of natural gas are physically injected into or withdrawn from storage. CPG includes the subsidiary CEVCO, which owns the mineral rights to approximately 460,000 acres in the Marcellus and Utica shale areas. CEVCO leases or contributes the mineral rights to producers in return for royalty interest. Royalties from mineral interests are recognized on an accrual basis when earned and realized. Royalty revenue was $21.5 million , $26.5 million and $43.8 million for the years ended December 31, 2016 , 2015 and 2014 , respectively, and is included in "Other revenues" on the Statements of Consolidated and Combined Operations. CPG periodically recognizes gains on the conveyance of mineral interest related to pooling of assets (production rights) in joint undertakings intended to find, develop, or produce oil or gas from a particular property or group of properties. The gains are initially deferred if CPG has a substantial obligation for future performance. As the obligation for future performance is satisfied, the deferred revenue is relieved and the associated gain is recognized. Gains on conveyances amounted to $16.9 million , $52.3 million and $34.5 million for the years ended December 31, 2016 , 2015 and 2014 , respectively, and are included in "Gain on sale of assets" on the Statements of Consolidated and Combined Operations.
Estimated Rate Refunds	Estimated Rate Refunds . CPG collects revenue subject to refund pending final determination in rate proceedings. In connection with such revenues, estimated rate refund liabilities are recorded which reflect management’s current judgment of the ultimate outcomes of the proceedings. No provisions are made when, in the opinion of management, the facts and circumstances preclude a reasonable estimate of the outcome.
Accounting For Exchange And Balancing Arrangements Of Natural Gas	Accounting for Exchange and Balancing Arrangements of Natural Gas. CPG enters into balancing and exchange arrangements of natural gas as part of its operations. CPG records a receivable or payable for its respective cumulative gas imbalances. These receivables and payables are recorded as “Exchange gas receivable” or “Exchange gas payable” on CPG’s Consolidated Balance Sheets, as appropriate.
Income Taxes And Investment Tax Credits	Income Taxes and Investment Tax Credits. CPG records income taxes to recognize full inter period tax allocations. Under the liability method, deferred income taxes are provided for the tax consequences of temporary differences by applying enacted statutory tax rates applicable to future years to differences between the financial statement carrying amounts and the tax basis of existing assets and liabilities. To the extent certain deferred income taxes of CPG are recoverable or payable through future rates, regulatory assets and liabilities have been established. Subsequent to the Merger, CPG is included in the consolidated Federal income tax return filed by US Parent and is a party to a Federal Tax Allocation Agreement with US Parent. The tax allocation agreement 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. In prior years, and for the period ending July 1, 2015, CPG joined in the filing of consolidated federal and state income tax returns with NiSource. CPG was a party to an agreement (“Tax Allocation Agreement”) that provides for the allocation of consolidated tax liabilities. The Tax Allocation Agreement generally provides that each party is allocated an amount of tax similar to that which would be owed had the party been separately subject to tax. In addition, the Tax Allocation Agreement provides that tax benefits associated with NiSource parent’s tax losses, excluding tax benefits from interest expense on acquisition debt, are allocated to and reduce the income tax liability of all NiSource subsidiaries having a positive separate company tax liability in a particular tax year. The amounts of such tax benefits allocated to CPG that were recorded in equity in 2016 , 2015 and 2014 were zero , $5.8 million and $1.3 million , respectively.
Environmental Expenditures	Environmental Expenditures. CPG accrues for costs associated with environmental remediation obligations when the incurrence of such costs is probable and the amounts can be reasonably estimated, regardless of when the expenditures are actually made. The undiscounted estimated future expenditures are based on currently enacted laws and regulations, existing technology and estimated site-specific costs where assumptions may be made about the nature and extent of site contamination, the extent of cleanup efforts, costs of alternative cleanup methods and other variables. The liability is adjusted as further information is discovered or circumstances change. The reserves for estimated environmental expenditures are recorded on the Consolidated Balance Sheets in “Other Accruals” for short-term portions of these liabilities and “Other noncurrent liabilities” for the respective long-term portions of these liabilities. CPG establishes regulatory assets on the Consolidated Balance Sheets to the extent that future recovery of environmental remediation costs is probable through the regulatory process. Please see Note 17, "Other Commitments and Contingencies" in the Notes to Consolidated and Combined Financial Statements for further discussion.
Accounting For Investments	Accounting for Investments. CPG accounts for its ownership interests in Millennium Pipeline using the equity method of accounting. Columbia Gas Transmission owns a 47.5% interest in Millennium Pipeline. The equity method of accounting is applied for investments in unconsolidated companies where CPG (or a subsidiary) owns 20 to 50 percent of the voting rights and can exercise significant influence. CPG owns a 50.0% interest in Hardy Storage for the periods presented. CPG reflects the investment in Hardy Storage as an equity method investment. Columbia Midstream entered into a 50:50 joint venture in 2012 with Hilcorp to construct Pennant, a new wet natural gas gathering infrastructure and NGL processing facilities to support natural gas production in the Utica Shale region of northeastern Ohio and western Pennsylvania. During the third quarter of 2015, an additional member, an affiliate of Williams Partners, joined the Pennant joint venture. Williams Partners' initial ownership investment in Pennant is 5.00% , and by funding specified investment amounts for future growth projects, Williams Partners can invest directly in the growth of Pennant. Such funding will potentially increase Williams Partners' 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 50.0% to 47.5% . During 2016, Williams Partners funded additional specified growth projects. As a result Columbia Midstream's ownership interest decreased to 47.0% . CPG accounts for the joint venture under the equity method of accounting.
Natural Gas and Oil Properties	Natural Gas and Oil Properties. CEVCO participates as a working interest partner in the development of a broader acreage dedication. The working interest allows CEVCO to invest in the drilling operations of the partnership in addition to a royalty interest in well production. Please see Note 1K, “Revenue Recognition,” in the Notes to Consolidated and Combined Financial Statements for further discussion regarding the royalty revenue. CEVCO uses the successful efforts method of accounting for natural gas and oil producing activities for their portion of drilling activities. Capitalized well costs are depleted based on the units of production method. CEVCO’s portion of unproved property investment is periodically evaluated for impairment. The majority of these costs generally relate to CEVCO’s portion of the working interest. The costs are capitalized and evaluated as to recoverability, based on changes brought about by economic factors and potential shifts in business strategy employed by management. Impairment of individually significant unproved property is assessed on a field-by-field basis considering a combination of time, geologic and engineering factors. The following table reflects the changes in capitalized exploratory well costs for the years ended December 31, 2016 and 2015 : (in millions) 2016 2015 Beginning Balance $ 1.7 $ 14.9 Additions pending the determination of proved reserves — 1.3 Reclassifications of proved properties (1.3 ) (14.5 ) Ending Balance $ 0.4 $ 1.7 As of December 31, 2016 , there was $0.3 million of capitalized exploratory well costs that have been capitalized for more than one year relating to one project initiated in 2013.

Nature of Operations and Summ36

Nature of Operations and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of AFUDC Debt and Equity Rates	2016 2015 2014 Debt Equity Debt Equity Debt Equity Columbia Gas Transmission 0.6 % 4.8 % 1.8 % 6.3 % 0.9 % 3.0 % Columbia Gulf 0.6 % 3.7 % 2.9 % 6.3 % 2.1 % 9.4 %
Capitalized Exploratory Well Costs, Roll Forward	(in millions) 2016 2015 Beginning Balance $ 1.7 $ 14.9 Additions pending the determination of proved reserves — 1.3 Reclassifications of proved properties (1.3 ) (14.5 ) Ending Balance $ 0.4 $ 1.7

CPPL Initial Public Offering (T

CPPL Initial Public Offering (Tables)	12 Months Ended
	Dec. 31, 2016
Initial Public Offering [Abstract]
Change From Net Income Attributable to CPG and Transfers to Noncontrolling Interest	Year Ended December 31, (in millions) 2016 2015 Net income attributable to CPG $ 116.8 $ 267.2 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 $ 116.8 $ 494.3

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2016
Long-term Debt, Current and Noncurrent [Abstract]
Schedule Of Outstanding Long Term Debt Maturities	Year Ending December 31, (in millions) 2017 $ — 2018 500.0 2019 — 2020 750.0 2021 — After 1,500.0 Total (1) $ 2,750.0 (1) This amount excludes unamortized discount and unamortized debt issuance costs of $3.4 million and $18.0 million , respectively. The unamortized discount and unamortized debt issuance costs applicable to the Notes are being amortized over the weighted average life of the Notes.

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Schedule Of Property, Plant And Equipment	At December 31, (in millions) 2016 2015 Property, plant and equipment Pipeline and other transmission assets $ 6,681.2 $ 6,160.4 Storage facilities 1,415.3 1,370.1 Gas stored base gas 299.5 299.5 Gathering and processing facilities 566.9 370.2 Construction work in process 1,097.0 487.6 General plant, software, and other assets 401.3 364.5 Property, plant and equipment 10,461.2 9,052.3 Accumulated depreciation and amortization (3,126.2 ) (2,988.6 ) Net property, plant and equipment $ 7,335.0 $ 6,063.7
Schedule of Depreciation Rates	Year Ended December 31, 2016 2015 2014 Depreciation rates Pipeline and other transmission assets 1.00% - 2.50% 1.00% - 2.50% 1.00% - 2.50% Storage facilities 2.19% - 3.00% 2.19% - 3.00% 2.19% - 3.30% Gathering and processing facilities 1.67% - 2.50% 1.67% - 2.50% 1.67% - 2.50% General plant, software, and other assets 1.00% - 20.00% 1.00% - 21.00% 1.00% - 10.00%

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2016
Asset Retirement Obligation [Abstract]
Changes In Liability For Asset Retirement Obligations	(in millions) 2016 2015 Beginning Balance $ 25.7 $ 23.2 Accretion expense 1.1 1.2 Additions — 4.1 Change in estimated cash flows (6.0 ) (2.8 ) Ending Balance $ 20.8 $ 25.7

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2016
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Assets	At December 31, (in millions) 2016 2015 Assets Unrecognized pension benefit and other postretirement benefit costs $ 111.3 $ 135.2 Other postretirement costs 6.3 9.0 Deferred taxes on AFUDC equity 57.0 35.4 Other 2.3 3.1 Total Regulatory Assets $ 176.9 $ 182.7
Regulatory Liabilities	At December 31, (in millions) 2016 2015 Liabilities Cost of removal $ 141.5 $ 154.7 Regulatory effects of accounting for income taxes 10.2 10.6 Modernization revenue sharing 7.4 — Other postretirement costs 134.3 155.6 Other — 1.9 Total Regulatory Liabilities $ 293.4 $ 322.8

Equity Method Investments (Tabl

Equity Method Investments (Tables)	12 Months Ended
	Dec. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments Schedule of Ownership Percentage	The following is a list of CPG's equity method investments at December 31, 2016 : Investee Type of Investment % of Voting Power or Interest Held Hardy Storage Company, LLC LLC Membership 50.0 % Pennant Midstream, LLC LLC Membership 47.0 % Millennium Pipeline Company, L.L.C. LLC Membership 47.5 %
Schedule Of Equity Method Investments	Year Ended December 31, (in millions) 2016 2015 2014 Millennium Pipeline Statement of Income Data: Net Revenues $ 205.0 $ 206.3 $ 190.5 Operating Income 138.1 136.1 128.8 Net Income 102.5 98.0 89.6 Balance Sheet Data: Current Assets 34.8 35.7 32.1 Noncurrent Assets 969.8 987.1 1,016.3 Current Liabilities 48.0 44.4 42.6 Noncurrent Liabilities 497.2 535.8 568.3 Total Members’ Equity 459.4 442.6 437.5 Contribution/Distribution Data: (1) Contributions to Millennium Pipeline 6.2 1.4 2.6 Distribution of earnings from Millennium Pipeline 48.9 47.5 35.6 Hardy Storage Statement of Income Data: Net Revenues $ 23.5 $ 23.4 $ 23.6 Operating Income 15.7 15.3 16.1 Net Income 11.2 10.3 10.6 Balance Sheet Data: Current Assets 10.3 12.1 12.0 Noncurrent Assets 151.3 155.5 157.4 Current Liabilities 17.2 19.3 17.1 Noncurrent Liabilities 57.5 68.5 77.4 Total Members’ Equity 86.9 79.8 74.9 Contribution/Distribution Data: (1) Contributions to Hardy Storage — — — Distribution of earnings from Hardy Storage 2.0 2.6 2.2 Pennant Statement of Income Data: Net Revenues $ 38.2 $ 34.6 $ 8.5 Operating Income (Loss) 21.2 17.8 (2.4 ) Net Income (Loss) 21.2 17.8 (2.4 ) Balance Sheet Data: Current Assets 9.8 11.0 23.7 Noncurrent Assets 384.0 389.6 380.0 Current Liabilities 3.5 8.4 8.6 Total Members’ Equity 390.3 392.2 395.1 Contribution/Distribution Data: (1) Contributions to Pennant — — 66.6 Distribution of earnings from Pennant 10.6 7.1 — Return of capital from Pennant 2.2 16.0 — (1) Contribution and distribution data represents CPG's portion based on CPG's ownership percentage of each investment.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Schedule Of Components Of Income Tax Expense	Year Ended December 31, (in millions) 2016 2015 2014 Income Taxes Current Federal $ (55.7 ) $ 12.1 $ 19.5 State 4.2 9.1 7.6 Total Current (51.5 ) 21.2 27.1 Deferred Federal 116.3 120.2 119.2 State 13.0 11.6 23.5 Total Deferred 129.3 131.8 142.7 Deferred Investment Credits — — (0.1 ) Total Income Taxes $ 77.8 $ 153.0 $ 169.7
Schedule Of Reasons Behind Differences In Computation Of Total Income Taxes	Year Ended December 31, (in millions) 2016 2015 2014 Book income from Continuing Operations before income taxes $ 231.5 $ 460.5 $ 438.4 Tax expense at statutory federal income tax rate 81.0 35.0 % 161.2 35.0 % 153.5 35.0 % Increases (reductions) in taxes resulting from: State income taxes, net of federal income tax benefit 11.2 4.8 13.4 2.9 20.3 4.6 Noncontrolling interest (13.0 ) (5.6 ) (14.0 ) (3.0 ) — — AFUDC-Equity (11.2 ) (4.8 ) (9.2 ) (2.0 ) (3.7 ) (0.8 ) Transaction cost 8.7 3.8 — — — — Other, net 1.1 0.4 1.6 0.3 (0.4 ) (0.1 ) Total Income Taxes $ 77.8 33.6 % $ 153.0 33.2 % $ 169.7 38.7 %
Schedule Of Principal Components Of Net Deferred Tax Liability	At December 31, (in millions) 2016 2015 Deferred tax liabilities Accelerated depreciation and other property differences $ 1,625.8 $ 1,429.2 Pension and other postretirement/postemployment benefits 31.1 29.9 Other regulatory assets 67.8 71.8 Equity method investments 130.2 124.3 Total Deferred Tax Liabilities 1,854.9 1,655.2 Deferred tax assets Other regulatory liabilities (104.9 ) (126.8 ) Net operating loss carryforward (231.7 ) (141.4 ) Other (17.9 ) (38.9 ) Total Deferred Tax Assets (354.5 ) (307.1 ) Net Deferred Tax Liabilities $ 1,500.4 $ 1,348.1

Pension and Other Postretirem44

Pension and Other Postretirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2016
Pension and Other Postretirement Benefit Expense [Abstract]
Schedule Of Allocation of Plan Assets	Asset Mix Policy of Funds: Defined Benefit Pension Plan Postretirement Benefit Plan Asset Category Minimum Maximum Minimum Maximum Domestic Equities 35% 55% 35% 55% International Equities 10% 20% 15% 25% Fixed Income 30% 50% 20% 50% Short-Term Investments 0% 10% 0% 10% Pension Plan and Postretirement Plan Asset Mix at December 31, 2016 and December 31, 2015 : December 31, 2016 Defined Benefit Postretirement Asset Class Asset Value % of Total Assets Asset Value % of Total Assets (in millions) (in millions) Domestic Equities $ 148.7 42.7 % $ 95.9 41.5 % International Equities 56.3 16.2 % 43.4 18.8 % Fixed Income 136.3 39.2 % 76.9 33.2 % Cash/Other 6.8 1.9 % 15.1 6.5 % Total $ 348.1 100.0 % $ 231.3 100.0 % December 31, 2015 Defined Benefit Postretirement Asset Class Asset Value % of Total Assets Asset Value % of Total Assets (in millions) (in millions) Domestic Equities $ 141.0 39.4 % $ 101.6 44.4 % International Equities 62.5 17.5 % 42.8 18.8 % Fixed Income 123.3 34.4 % 76.6 33.6 % Cash/Other 31.0 8.7 % 7.2 3.2 % Total $ 357.8 100.0 % $ 228.2 100.0 %
Schedule Of Fair Value and Changes In The Fair Value Of The Plan Assets	Fair Value Measurements (in millions) December 31, Quoted Prices in Active Significant Other Significant Pension plan assets Cash $ 0.2 $ 0.2 $ — $ — Fixed income securities Government 8.8 — 8.8 — Corporate 19.5 — 19.5 — Commingled funds Short-term money markets (2) 6.6 U.S. equities (2) 93.1 International equities (2) 56.3 Fixed income (2) 73.2 Mutual funds U.S. equities 55.6 55.6 — — Fixed income 34.8 34.8 — — Pension plan assets subtotal 348.1 90.6 28.3 — Other postretirement benefit plan assets Cash 0.4 0.4 — — Commingled funds Short-term money markets (2) 14.7 U.S. equities (2) 1.0 Mutual funds U.S. equities 94.9 94.9 — — International equities 43.4 43.4 — — Fixed income 76.9 76.9 — — Other postretirement benefit plan assets subtotal 231.3 215.6 — — Due to brokers, net (1) (0.2 ) Accrued investment income/dividends 0.6 Total pension and other postretirement benefit plan assets $ 579.8 $ 306.2 $ 28.3 $ — (1) This class represents pending trades with brokers. (2) This class of investments is measured at fair value using the net asset value per share and has not been classified in the fair value hierarchy. The table below sets forth a summary of unfunded commitments, redemption frequency and redemption notice periods for certain investments that are measured at fair value using the net asset value per share for the year ended December 31, 2016: (in millions) Fair Value Unfunded Commitments Redemption Frequency Redemption Notice Period Commingled Funds Short-term money markets $ 21.3 $ — Daily 1 day U.S. equities 94.1 — Daily 1 day International equities 56.3 — Daily 2 days Fixed income 73.2 — Daily 2-3 days Total $ 244.9 — Fair Value Measurements at December 31, 2015 : Fair Value Measurements (in millions) December 31, Quoted Prices in Active Significant Other Significant Pension plan assets Cash $ 0.9 $ 0.9 $ — $ — Equity securities International equities 6.6 6.6 — — Fixed income securities Government 8.5 — 8.5 — Corporate 13.0 — 13.0 — Commingled funds Short-term money markets (2) 31.1 U.S. equities (2) 141.0 International equities (2) 55.6 Fixed income (2) 100.9 Pension plan assets subtotal 357.6 7.5 21.5 — Other postretirement benefit plan assets Commingled funds Short-term money markets (2) 7.3 U.S. equities (2) 13.9 Mutual funds U.S. equities 87.7 87.7 — — International equities 42.8 42.8 — — Fixed income 76.5 76.5 — — Other postretirement benefit plan assets subtotal 228.2 207.0 — — Due to brokers, net (1) (0.4 ) Accrued investment income/dividends 0.6 Total pension and other postretirement benefit plan assets $ 586.0 $ 214.5 $ 21.5 $ — (1) This class represents pending trades with brokers. (2) This class of investments is measured at fair value using the net asset value per share and has not been classified in the fair value hierarchy. The table below sets forth a summary of changes in the fair value of the Plan’s Level 3 assets for the year ended December 31, 2015 : (in millions) Balance at January 1, 2015 Total gains or losses (unrealized / realized) Purchases (Sales) Transfers into/(out of) level 3 Separation Allocation (1) Balance at December 31, 2015 Fixed income securities Other fixed income $ 0.1 $ — $ — $ — $ — $ (0.1 ) $ — Private equity limited partnerships U.S. multi-strategy 8.5 — — — — (8.5 ) — International multi-strategy 5.3 — — — — (5.3 ) — Distressed opportunities 1.1 — — — — (1.1 ) — Real estate 2.6 — — — — (2.6 ) — Total $ 17.6 $ — $ — $ — $ — $ (17.6 ) $ — (1) Level 3 assets were not contributed to the CPG Plans upon Separation from NiSource and no subsequent investments were made in Level 3 assets post Separation. The table below sets forth a summary of unfunded commitments, redemption frequency and redemption notice periods for certain investments that are measured at fair value using the net asset value per share for the year ended December 31, 2015: (in millions) Fair Value Unfunded Commitments Redemption Frequency Redemption Notice Period Commingled Funds Short-term money markets $ 38.4 $ — Daily 1 day U.S. equities 154.9 — Monthly 3 days International equities 55.6 — Monthly 14-30 days Fixed income 100.9 — Monthly 3 days Total $ 349.8 $ —
Schedule Of Reconciliation Of The Plan Funded Status	Pension Benefits Other Postretirement Benefits (in millions) 2016 2015 2016 2015 Change in projected benefit obligation (1) Benefit obligation at beginning of year $ 404.5 $ 397.6 $ 112.1 $ 124.2 Service cost 6.4 5.9 0.9 1.0 Interest cost 15.1 15.0 4.5 4.7 Plan participants’ contributions — — 2.8 2.3 Actuarial (gain) loss (4.7 ) (6.9 ) 2.1 (12.4 ) Settlement loss 3.2 — — — Benefits paid (48.8 ) (29.7 ) (13.6 ) (9.8 ) Estimated benefits paid by incurred subsidy — — 0.3 0.3 Transfer of participant balances from NiSource plans (2) — 22.6 — 1.8 Projected benefit obligation at end of year $ 375.7 $ 404.5 $ 109.1 $ 112.1 Change in plan assets Fair value of plan assets at beginning of year $ 357.8 $ 351.0 $ 228.2 $ 223.8 Actual return on plan assets 30.7 1.2 13.6 (2.5 ) Employer contributions 8.4 20.0 0.3 13.5 Plan participants’ contributions — — 2.8 2.3 Benefits paid (48.8 ) (29.7 ) (13.6 ) (9.8 ) Transfer of participant balances from NiSource plans (2) — 15.3 — 0.9 Fair value of plan assets at end of year $ 348.1 $ 357.8 $ 231.3 $ 228.2 Funded status at end of year $ (27.6 ) $ (46.7 ) $ 122.2 $ 116.1 Amounts recognized in the balance sheet consist of: Noncurrent assets $ — $ — $ 122.2 $ 116.1 Current liabilities — (0.8 ) — — Noncurrent liabilities (27.6 ) (45.9 ) — — Net amount recognized at end of year (3) $ (27.6 ) $ (46.7 ) $ 122.2 $ 116.1 Amounts recognized in AOCI or regulatory assets/liabilities (4) Unrecognized prior service credit $ (2.6 ) $ (3.7 ) $ (1.3 ) $ (2.0 ) Unrecognized actuarial loss (gain) 133.0 164.5 (0.7 ) (3.9 ) Total recognized AOCI or regulatory assets/liabilities $ 130.4 $ 160.8 $ (2.0 ) $ (5.9 ) (1) The change in benefit obligation for Pension Benefits represents the change in Projected Benefit Obligation while the change in benefit obligation for Other Postretirement Benefits represents the change in Accumulated Postretirement Benefit Obligation. (2) Reflects the transfer of additional pension and OPEB plan participants to CPGSC upon Separation from NiSource that were determined in the current year. (3) CPG recognizes in its Consolidated Balance Sheets the underfunded and overfunded status of its various defined benefit postretirement plans, measured as the difference between the fair value of the plan assets and the benefit obligation. (4) CPG determined that the future recovery of pension and other postretirement benefits costs is probable. CPG recorded regulatory assets and liabilities of $111.3 million and zero , respectively, as of December 31, 2016 , and $135.2 million and $0.7 million , respectively, as of December 31, 2015 that would otherwise have been recorded to accumulated other comprehensive loss.
Schedule Of Significant Actuarial Assumptions In Determining Funded Status Plan	Pension Benefits Other Postretirement Benefits 2016 2015 2016 2015 Weighted-average assumptions to Determine Benefit Obligation Discount Rate 4.10 % 4.05 % 4.25 % 4.29 % Rate of Compensation Increases 2.50 % 4.00 % Health Care Trend Rates Trend for Next Year 8.47 % 8.39 % Ultimate Trend 4.50 % 4.50 % Year Ultimate Trend Reached 2024 2022
Schedule Of One-Percentage-Point Change In Assumed Health Care Cost Trend Rates	(in millions) 1% point increase 1% point decrease Effect on service and interest components of net periodic cost $ 0.1 $ (0.1 ) Effect on accumulated postretirement benefit obligation 2.6 (2.4 )
Schedule Of Expected Payments To Participants In Pension Plan	(in millions) Pension Benefits Other Federal Year(s) 2017 $ 32.3 $ 7.8 $ 0.5 2018 33.1 7.8 0.5 2019 33.8 7.8 0.4 2020 35.2 7.7 0.4 2021 34.9 7.6 0.4 2022-2026 168.8 35.5 1.2
Components Of The Plans' Net Periodic Benefits Cost	Pension Benefits Other Postretirement Benefits (in millions) 2016 2015 2014 2016 2015 2014 Components of Net Periodic Benefit Cost (Income) Service cost $ 6.4 $ 5.9 $ 4.8 $ 0.9 $ 1.0 $ 1.1 Interest cost 15.1 15.0 15.7 4.5 4.7 4.6 Expected return on assets (25.0 ) (28.2 ) (27.3 ) (15.0 ) (18.1 ) (16.6 ) Amortization of prior service (credit) cost (1.2 ) (1.1 ) (1.1 ) (0.7 ) (0.3 ) 0.1 Recognized actuarial loss (gain) 12.2 9.9 7.5 0.3 (0.3 ) — Net Periodic Benefit Cost (Income) 7.5 1.5 (0.4 ) (10.0 ) (13.0 ) (10.8 ) Additional loss recognized due to: Settlement loss 12.3 — — — — — Total Net Periodic Benefit Cost (Income) $ 19.8 $ 1.5 $ (0.4 ) $ (10.0 ) $ (13.0 ) $ (10.8 )
Schedule Of Key Assumptions That Were Used To Calculate The Net Periodic Benefits Cost	Pension Benefits Other Postretirement Benefits 2016 2015 2014 2016 2015 2014 Weighted-average Assumptions to Determine Net Periodic Benefit Cost Discount Rate 3.90 % 3.84 % 4.34 % 4.12 % 4.10 % 4.76 % Expected Long-Term Rate of Return on Plan Assets 7.29 % 8.20 % 8.30 % 6.81 % 8.05 % 8.14 % Rate of Compensation Increases 4.00 % 4.00 % 4.00 %
Schedule Of Changes In Plan Assets And Projected Benefit Obligations Recognized In Other Comprehensive Income	Pension Benefits Other Postretirement Benefits (in millions) 2016 2015 2016 2015 Other changes in plan assets and projected benefit obligations recognized in other comprehensive income or regulatory assets or liabilities Settlements $ (12.3 ) $ — $ — $ — Net actuarial (gain) loss (7.1 ) 25.6 3.5 8.6 Less: amortization of prior service cost 1.2 1.1 0.7 0.3 Less: amortization of net actuarial (gain) loss (12.2 ) (9.9 ) (0.3 ) 0.3 Total recognized in other comprehensive income or regulatory assets or liabilities $ (30.4 ) $ 16.8 $ 3.9 $ 9.2 Amount recognized in net periodic benefit cost and other comprehensive income or regulatory assets or liabilities $ (10.6 ) $ 18.3 $ (6.1 ) $ (3.8 )

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Carrying Amount And Estimated Fair Values Of Financial Instruments	At December 31, (in millions) Carrying Amount 2016 (1) Estimated Fair Value 2016 Carrying Amount 2015 (1) Estimated Fair Value 2015 Long-term debt $ 2,750.0 $ 2,868.8 $ 2,750.0 $ 2,592.1 (1) The carrying amount of the Notes differs from the Long-term debt balance on the Consolidated Balance Sheets 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 (Table

Share-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2016
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule Of Transactions Of Share Based Compensation Other Than Stock Options	Restricted Stock Units Weighted Average Grant Date Fair Value Nonvested at December 31, 2015 2,268,792 $ 18.85 Granted 12,144 16.86 Forfeited (22,590 ) 22.71 Vested (2,258,346 ) 18.80 Outstanding at December 31, 2016 — $ —
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule Of Transactions Of Share Based Compensation Other Than Stock Options	Contingent Awards Weighted Average Grant Date Fair Value Nonvested at December 31, 2015 161,504 $ 28.16 Granted 955,848 17.79 Forfeited — — Vested (1,117,352 ) 19.29 Outstanding at December 31, 2016 — $ —

Other Commitments and Conting47

Other Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Schedule of Guarantor Obligations	(in millions) Total 2017 2018 2019 2020 2021 After Other guarantees $ 4.7 $ 2.2 $ — $ — $ — $ — $ 2.5
Future Minimum Lease Payments Required Under Operating And Capital Leases	(in millions) Operating Leases (1) 2017 $ 8.7 2018 7.4 2019 6.6 2020 6.3 2021 5.5 After 23.5 Total future minimum payments $ 58.0 (1) Operating lease expense includes amounts for fleet leases and storage well leases that can be renewed beyond the initial lease term, but the anticipated payments associated with the renewals do not meet the definition of expected minimum lease payments and, therefore, are not included above.
Estimated Aggregate Amounts Of Minimum Fixed Payments On Purchase And Service Obligations	(in millions) Pipeline Service Agreements IBM Service Agreement 2017 $ 67.0 $ 34.3 2018 63.4 31.8 2019 55.9 31.2 2020 38.4 30.9 2021 32.2 — After 187.0 — Total future minimum payments $ 443.9 $ 128.2

Accumulated Other Comprehensi48

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Dec. 31, 2016
Components of Accumulated Other Comprehensive Income (Loss) [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	(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, 2014 - Predecessor $ (17.6 ) $ (8.2 ) $ (25.8 ) Other comprehensive income before reclassifications — (9.3 ) (9.3 ) Amounts reclassified from accumulated other comprehensive income 1.0 (0.4 ) 0.6 Net current-period other comprehensive income 1.0 (9.7 ) (8.7 ) Balance as of December 31, 2014 $ (16.6 ) $ (17.9 ) $ (34.5 ) Other comprehensive income before reclassifications (0.9 ) 5.0 4.1 Amounts reclassified from accumulated other comprehensive income (2) 1.1 0.2 1.3 Net current-period other comprehensive income 0.2 5.2 5.4 Allocation of accumulated other comprehensive loss to noncontrolling interest 2.1 — 2.1 Balance as of December 31, 2015 $ (14.3 ) $ (12.7 ) $ (27.0 ) Other comprehensive income before reclassifications — 3.7 3.7 Amounts reclassified from accumulated other comprehensive income (2) 1.3 (1.7 ) (0.4 ) Net current-period other comprehensive income 1.3 2.0 3.3 Allocation of accumulated other comprehensive loss to noncontrolling interest 0.2 — 0.2 Balance as of December 31, 2016 $ (13.2 ) $ (10.7 ) $ (23.9 ) (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)	12 Months Ended
	Dec. 31, 2016
Other Nonoperating Income (Expense) [Abstract]
Schedule Of Other, Net	Year Ended December 31, (in millions) 2016 2015 2014 AFUDC Equity $ 34.9 $ 28.3 $ 11.0 Miscellaneous 0.2 1.0 (2.2 ) Total Other, net $ 35.1 $ 29.3 $ 8.8

Interest Expense (Tables)

Interest Expense (Tables)	12 Months Ended
	Dec. 31, 2016
Interest Expense [Abstract]
Schedule Of Interest Expense	Year Ended December 31, (in millions) 2016 2015 2014 Interest on long-term debt $ 111.0 $ 67.5 $ — Interest on short-term borrowings 0.2 1.4 — Debt discount/cost amortization (1) 10.2 3.1 — Allowance for funds used during construction (5.1 ) (6.8 ) — Other 2.8 2.4 — Total Interest Expense (2) $ 119.1 $ 67.6 $ — (1) Debt discount/cost amortization for 2016 primarily consists of the accelerated amortization of $5.7 million of deferred costs associated with the CPG and CPPL revolving credit facilities. Refer to Note 5, "Short-term Borrowings" for additional information regarding the early termination of the revolving credit facilities. (2) Refer to Note 4, "Transactions with Affiliates" for a discussion of interest expense-affiliated for the year ended December 31, 2016 , 2015 and 2014 .

Supplemental Cash Flow Inform51

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2016
Supplemental Cash Flow Information [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	Year Ended December 31, (in millions) 2016 2015 2014 Supplemental Disclosures of Cash Flow Information Non-cash transactions: Capital expenditures included in current liabilities (1) $ 146.1 $ 128.4 $ 78.5 Schedule of interest and income taxes paid: Cash paid for interest, net of interest capitalized amounts $ 111.1 $ 96.9 $ 53.6 Cash paid for income taxes (2) 4.1 32.3 21.2 (1) Capital expenditures included in current liabilities is comprised of "Accrued capital expenditures" and certain other amounts included within "Accounts payable" on the Consolidated Balance Sheets. (2) Cash paid for income taxes for the year ended December 31, 2015 includes $20.9 million paid to NiSource under the Tax Allocation Agreement.

Concentration of Credit Risk (T

Concentration of Credit Risk (Tables)	12 Months Ended
	Dec. 31, 2016
Risks and Uncertainties [Abstract]
Schedules of Concentration of Risk, by Risk Factor	Year Ended December 31, 2016 2015 2014 (in millions) Total Operating Revenues Percentage of Total Operating Revenues Total Operating Revenues Percentage of Total Operating Revenues Total Operating Revenues Percentage of Total Operating Revenues Columbia Gas of Ohio (1) $ 169.7 12.3 % $ 167.3 12.5 % $ 168.5 12.5 % (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 agreements with third parties which ultimately can decrease the net revenue amount CPG receives from Columbia Gas of Ohio in any given period.

Quarterly Financial Data (Una53

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Schedule Of Quarterly Financial Data	(in millions) First Quarter Second Quarter Third Quarter Fourth Quarter 2016 Total Operating Revenues $ 364.5 $ 313.9 $ 327.1 $ 376.5 Operating Income (Loss) 151.7 91.5 (53.0 ) 127.4 Income (Loss) from Continuing Operations 86.6 48.6 (49.6 ) 68.1 Results from Discontinued Operations - net of taxes 0.2 — — — Net Income (Loss) Attributable to CPG 72.2 38.9 (52.5 ) 58.2 2015 Total Operating Revenues $ 340.0 $ 316.1 $ 320.9 $ 357.9 Operating Income 162.7 107.3 135.9 122.2 Income from Continuing Operations 97.1 60.1 74.9 75.4 Results from Discontinued Operations - net of taxes — (0.3 ) (0.1 ) — Net Income Attributable to CPG 90.0 50.8 63.0 63.4

Condensed Consolidating Finan54

Condensed Consolidating Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2016
Guarantees [Abstract]
Condensed Consolidating Balance Sheets	CONDENSED CONSOLIDATING BALANCE SHEETS As of December 31, 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 $ 38.8 $ 30.0 $ — $ — $ 11.1 $ — $ 79.9 Accounts receivable, net — 0.1 — — 194.1 — 194.2 Accounts receivable-affiliated 799.6 579.5 — — 190.0 (1,513.3 ) 55.8 Materials and supplies, at average cost — — — — 26.0 — 26.0 Exchange gas receivable — — — — 27.7 — 27.7 Deferred property taxes — — — — 61.2 — 61.2 Taxes receivable 68.6 43.6 — — — (112.2 ) — Prepayments and other 0.3 0.4 — — 28.2 — 28.9 Total Current Assets 907.3 653.6 — — 538.3 (1,625.5 ) 473.7 Investments Unconsolidated affiliates — — — — 446.7 — 446.7 Consolidated affiliates 5,421.1 7,482.0 6,089.2 — — (18,992.3 ) — Other investments — — — — 0.8 — 0.8 Total Investments 5,421.1 7,482.0 6,089.2 — 447.5 (18,992.3 ) 447.5 Property, Plant and Equipment Property, plant and equipment — — — — 10,461.2 — 10,461.2 Accumulated depreciation and amortization — — — — (3,126.2 ) — (3,126.2 ) Net Property, Plant and Equipment — — — — 7,335.0 — 7,335.0 Other Noncurrent Assets Regulatory assets — 56.5 — — 116.4 — 172.9 Goodwill — — 1,975.5 — — — 1,975.5 Notes receivable-affiliated 1,848.2 — — — — (1,848.2 ) — Postretirement and postemployment benefits assets — 0.8 — — 121.4 (0.4 ) 121.8 Deferred income taxes — — — — 84.8 (84.8 ) — Deferred charges and other 1.7 — — — 9.6 — 11.3 Total Other Noncurrent Assets 1,849.9 57.3 1,975.5 — 332.2 (1,933.4 ) 2,281.5 Total Assets $ 8,178.3 $ 8,192.9 $ 8,064.7 $ — $ 8,653.0 $ (22,551.2 ) $ 10,537.7 CONDENSED CONSOLIDATING BALANCE SHEETS (continued) As of December 31, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated LIABILITIES, TEMPORARY EQUITY AND EQUITY Current Liabilities Short-term borrowings-affiliated $ — $ — $ 570.8 $ — $ 923.6 $ (1,494.4 ) $ — Accounts payable — 0.6 — — 69.8 — 70.4 Accounts payable-affiliated 7.0 5.1 0.8 — 10.0 (18.9 ) 4.0 Customer deposits — — — — 17.3 — 17.3 Taxes accrued — — — — 229.1 (112.2 ) 116.9 Interest accrued 9.3 — — — 0.1 — 9.4 Exchange gas payable — — — — 27.2 — 27.2 Deferred revenue — — — — 3.9 — 3.9 Accrued capital expenditures — — — — 111.4 — 111.4 Accrued compensation and related costs — — — — 62.3 — 62.3 Other accruals 0.1 0.5 — — 109.5 — 110.1 Total Current Liabilities 16.4 6.2 571.6 — 1,564.2 (1,625.5 ) 532.9 Noncurrent Liabilities Long-term debt 2,728.6 — — — — — 2,728.6 Long-term debt-affiliated — 1,217.3 — — 630.9 (1,848.2 ) — Deferred income taxes 42.8 1,542.4 — — — (84.8 ) 1,500.4 Accrued liability for postretirement and postemployment benefits 0.7 6.4 — — 25.5 (0.4 ) 32.2 Regulatory liabilities — 10.2 — — 263.4 — 273.6 Asset retirement obligations — — — — 20.8 — 20.8 Other noncurrent liabilities 0.4 1.8 — — 57.6 — 59.8 Total Noncurrent Liabilities 2,772.5 2,778.1 — — 998.2 (1,933.4 ) 4,615.4 Total Liabilities 2,788.9 2,784.3 571.6 — 2,562.4 (3,558.9 ) 5,148.3 Temporary Equity Redeemable noncontrolling interest 952.9 952.9 — — — (952.9 ) 952.9 Equity Common stock 0.1 — — — — — 0.1 Additional paid-in capital 4,513.8 — — — — — 4,513.8 Accumulated deficit (53.5 ) — — — (53.5 ) Net parent investment — 4,479.3 7,516.2 — 6,117.5 (18,113.0 ) — Accumulated other comprehensive loss (23.9 ) (23.6 ) (23.1 ) — (26.9 ) 73.6 (23.9 ) Total Equity 4,436.5 4,455.7 7,493.1 — 6,090.6 (18,039.4 ) 4,436.5 Total Liabilities, Temporary Equity and Equity $ 8,178.3 $ 8,192.9 $ 8,064.7 $ — $ 8,653.0 $ (22,551.2 ) $ 10,537.7 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	CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS Year Ended December 31, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 1,155.1 $ — $ 1,155.1 Storage revenues — — — — 196.5 — 196.5 Other revenues — — — — 30.4 — 30.4 Total Operating Revenues — — — — 1,382.0 — 1,382.0 Operating Expenses Operation and maintenance 146.6 0.8 — — 716.0 (0.2 ) 863.2 Operation and maintenance-affiliated 3.7 — — — — (3.7 ) — Depreciation and amortization — 0.7 — — 172.1 — 172.8 Gain on sale of assets — — — — (16.6 ) — (16.6 ) Impairment of long-lived assets — — — — 26.1 — 26.1 Property and other taxes 0.1 1.4 0.1 — 81.6 — 83.2 Total Operating Expenses 150.4 2.9 0.1 — 979.2 (3.9 ) 1,128.7 Equity Earnings in Unconsolidated Affiliates — — — — 64.3 — 64.3 Equity Earnings in Consolidated Affiliates 284.0 465.2 477.9 — — (1,227.1 ) — Operating Income 133.6 462.3 477.8 — 467.1 (1,223.2 ) 317.6 Other Income (Deductions) Interest expense (121.0 ) — — — (3.2 ) 5.1 (119.1 ) Interest expense-affiliated (2.1 ) (45.0 ) (3.7 ) — (31.6 ) 80.3 (2.1 ) Other, net 81.1 4.6 — — 34.8 (85.4 ) 35.1 Total Other Deductions, net (42.0 ) (40.4 ) (3.7 ) — — — (86.1 ) Income from Continuing Operations before Income Taxes 91.6 421.9 474.1 — 467.1 (1,223.2 ) 231.5 Income Taxes (62.1 ) 137.8 — — 2.1 — 77.8 Income from Continuing Operations 153.7 284.1 474.1 — 465.0 (1,223.2 ) 153.7 Income from Discontinued Operations-net of taxes 0.2 0.2 — — — (0.2 ) 0.2 Net Income 153.9 284.3 474.1 — 465.0 (1,223.4 ) 153.9 Less: Net income attributable to noncontrolling interest 37.1 37.1 — — — (37.1 ) 37.1 Net Income Attributable to CPG $ 116.8 $ 247.2 $ 474.1 $ — $ 465.0 $ (1,186.3 ) $ 116.8 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (continued) Year Ended December 31, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 1,054.4 $ — $ 1,054.4 Transportation revenues-affiliated — — — — 47.5 — 47.5 Storage revenues — — — — 171.4 — 171.4 Storage revenues-affiliated — — — — 26.2 — 26.2 Other revenues — — — — 35.4 — 35.4 Total Operating Revenues — — — — 1,334.9 — 1,334.9 Operating Expenses Operation and maintenance 20.5 (1.2 ) — — 632.8 — 652.1 Operation and maintenance-affiliated 2.2 0.4 — — 52.5 (2.2 ) 52.9 Depreciation and amortization — — — — 139.9 — 139.9 Gain on sale of assets — — — — (55.3 ) — (55.3 ) Impairment of long-lived assets — 1.8 — — 0.6 — 2.4 Property and other taxes — — — — 75.3 — 75.3 Total Operating Expenses 22.7 1.0 — — 845.8 (2.2 ) 867.3 Equity Earnings in Unconsolidated Affiliates — — — — 60.5 — 60.5 Equity Earnings in Consolidated Affiliates 341.2 529.4 529.6 — — (1,400.2 ) — Operating Income 318.5 528.4 529.6 — 549.6 (1,398.0 ) 528.1 Other Income (Deductions) Interest expense (73.0 ) — — — (1.5 ) 6.9 (67.6 ) Interest expense-affiliated (2.5 ) (40.8 ) — — (26.8 ) 40.8 (29.3 ) Other, net 45.4 0.5 3.5 — 27.6 (47.7 ) 29.3 Total Other Deductions, net (30.1 ) (40.3 ) 3.5 — (0.7 ) — (67.6 ) Income from Continuing Operations before Income Taxes 288.4 488.1 533.1 — 548.9 (1,398.0 ) 460.5 Income Taxes (19.1 ) 146.6 — — 25.5 — 153.0 Income from Continuing Operations 307.5 341.5 533.1 — 523.4 (1,398.0 ) 307.5 Loss from Discontinued Operations-net of taxes (0.4 ) (0.4 ) — — — 0.4 (0.4 ) Net Income 307.1 341.1 533.1 — 523.4 (1,397.6 ) 307.1 Less: Net income attributable to noncontrolling interest 39.9 39.9 — — — (39.9 ) 39.9 Net Income Attributable to CPG $ 267.2 $ 301.2 $ 533.1 $ — $ 523.4 $ (1,357.7 ) $ 267.2 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (continued) Year Ended December 31, 2014 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Operating Revenues Transportation revenues $ — $ — $ — $ — $ 990.8 $ — $ 990.8 Transportation revenues-affiliated — — — — 95.7 — 95.7 Storage revenues — — — — 144.0 — 144.0 Storage revenues-affiliated — — — — 53.2 — 53.2 Other revenues — — — — 64.3 — 64.3 Total Operating Revenues — — — — 1,348.0 — 1,348.0 Operating Expenses Operation and maintenance — (2.6 ) — — 631.0 — 628.4 Operation and maintenance-affiliated — 0.5 — — 122.7 — 123.2 Depreciation and amortization — — — — 118.8 — 118.8 Gain on sale of assets — — — — (34.5 ) — (34.5 ) Property and other taxes — — — — 67.1 — 67.1 Total Operating Expenses — (2.1 ) — — 905.1 — 903.0 Equity Earnings in Unconsolidated Affiliates — — — — 46.6 — 46.6 Equity Earnings in Consolidated Affiliates 268.7 269.6 — — — (538.3 ) — Operating Income 268.7 271.7 — — 489.5 (538.3 ) 491.6 Other Income (Deductions) Interest expense-affiliated — — — — (62.0 ) — (62.0 ) Other, net — (0.1 ) — — 8.9 — 8.8 Total Other Deductions, net — (0.1 ) — — (53.1 ) — (53.2 ) Income from Continuing Operations before Income Taxes 268.7 271.6 — — 436.4 (538.3 ) 438.4 Income Taxes — 2.9 — — 166.8 — 169.7 Income from Continuing Operations 268.7 268.7 — — 269.6 (538.3 ) 268.7 Loss from Discontinued Operations-net of taxes (0.6 ) (0.6 ) — — — 0.6 (0.6 ) Net Income $ 268.1 $ 268.1 $ — $ — $ 269.6 $ (537.7 ) $ 268.1
Condensed Consolidating Statements of Comprehensive Income	CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME Year Ended December 31, 2016 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Income $ 153.9 $ 284.3 $ 474.1 $ — $ 465.0 $ (1,223.4 ) $ 153.9 Other comprehensive income Net unrealized gain (loss) on cash flow hedges 1.3 (0.8 ) — — 2.1 (1.3 ) 1.3 Unrecognized pension and OPEB benefit 2.0 1.7 — — 0.3 (2.0 ) 2.0 Total other comprehensive income 3.3 0.9 — — 2.4 (3.3 ) 3.3 Total Comprehensive Income 157.2 285.2 474.1 — 467.4 (1,226.7 ) 157.2 Less: Comprehensive Income-noncontrolling interest 37.3 37.3 — — — (37.3 ) 37.3 Comprehensive Income-controlling interests $ 119.9 $ 247.9 $ 474.1 $ — $ 467.4 $ (1,189.4 ) $ 119.9 Year Ended December 31, 2015 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Income $ 307.1 $ 341.1 $ 533.1 $ — $ 523.4 $ (1,397.6 ) $ 307.1 Other comprehensive income Net unrealized gain (loss) on cash flow hedges 0.2 (1.6 ) — — 1.8 (0.2 ) 0.2 Unrecognized pension and OPEB benefit 5.2 5.4 — — (0.2 ) (5.2 ) 5.2 Total other comprehensive income 5.4 3.8 — — 1.6 (5.4 ) 5.4 Total Comprehensive Income 312.5 344.9 533.1 — 525.0 (1,403.0 ) 312.5 Less: Comprehensive Income-noncontrolling interest 40.0 40.0 — — — (40.0 ) 40.0 Comprehensive Income-controlling interests $ 272.5 $ 304.9 $ 533.1 $ — $ 525.0 $ (1,363.0 ) $ 272.5 Year Ended December 31, 2014 (in millions, net of taxes) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Income $ 268.1 $ 268.1 $ — $ — $ 269.6 $ (537.7 ) $ 268.1 Other comprehensive income Net unrealized gain (loss) on cash flow hedges 1.0 — — — 1.0 (1.0 ) 1.0 Unrecognized pension and OPEB cost (9.7 ) (9.7 ) — — — 9.7 (9.7 ) Total other comprehensive income (8.7 ) (9.7 ) — — 1.0 8.7 (8.7 ) Total Comprehensive Income $ 259.4 $ 258.4 $ — $ — $ 270.6 $ (529.0 ) $ 259.4
Condensed Consolidating Statements of Cash Flows	CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS Year Ended December 31, 2016 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Cash Flows from Operating Activities $ (213.6 ) $ 473.7 $ (3.0 ) $ — $ 712.0 $ (608.9 ) $ 360.2 Investing Activities Capital expenditures — — — — (1,438.1 ) — (1,438.1 ) Insurance recoveries — — — — 3.0 — 3.0 Change in short-term lendings-affiliated (736.1 ) (490.4 ) 3.3 — (37.9 ) 1,261.1 — Proceeds from disposition of assets — — — — 10.4 — 10.4 Contributions to equity investees — — — — (6.2 ) — (6.2 ) Distributions from equity investees — — — — 2.2 — 2.2 Other investing activities 10.3 — — — (9.7 ) — 0.6 Net Cash Flows (used for) provided by Investing Activities (725.8 ) (490.4 ) 3.3 — (1,476.3 ) 1,261.1 (1,428.1 ) Financing Activities Change in short-term borrowings — — — — (15.0 ) — (15.0 ) Change in short-term borrowings-affiliated 401.0 — 570.8 — 789.3 (1,261.1 ) 500.0 Payment of short-term borrowings-affiliated (500.0 ) — — — — — (500.0 ) Payment of capital lease obligations and other debt related costs (1.1 ) — — — (4.3 ) — (5.4 ) Issuance of common stock to TransCanada 500.1 — — — — — 500.1 Quarterly distributions to unitholders — — — — (76.9 ) 76.9 — Distribution to noncontrolling interest in Columbia OpCo — — (573.0 ) — — 573.0 — Distribution to noncontrolling interest — — — — — (41.0 ) (41.0 ) Acquisition of treasury stock (6.2 ) — — — — — (6.2 ) Dividends paid - common stock (105.1 ) — — — — — (105.1 ) Dividends paid - TransCanada (110.5 ) — — — — — (110.5 ) Net Cash Flows from (used for) Financing Activities 178.2 — (2.2 ) — 693.1 (652.2 ) 216.9 Change in cash and cash equivalents (761.2 ) (16.7 ) (1.9 ) — (71.2 ) — (851.0 ) 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 $ 38.8 $ 30.0 $ — $ — $ 11.1 $ — $ 79.9 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (continued) Year Ended December 31, 2015 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Cash Flows from Operating Activities $ (29.7 ) $ (49.6 ) $ 3.5 $ — $ 589.5 $ (20.2 ) $ 493.5 Investing Activities Capital expenditures — (32.7 ) — — (1,181.0 ) 32.7 (1,181.0 ) Insurance recoveries — — — — 2.1 — 2.1 Change in short-term lendings-affiliated — (83.9 ) (3.3 ) — (0.6 ) 233.3 145.5 Proceeds from disposition of assets — 26.2 — — 84.1 (32.7 ) 77.6 Contributions to equity investees — (1,217.3 ) (446.2 ) — (1.4 ) 1,663.5 (1.4 ) Distributions from equity investees — — — — 16.0 — 16.0 Other investing activities (5.2 ) — — — (22.2 ) — (27.4 ) Net Cash Flows used for Investing Activities (5.2 ) (1,307.7 ) (449.5 ) — (1,103.0 ) 1,896.8 (968.6 ) Financing Activities Change in short-term borrowings — — — — 15.0 — 15.0 Change in short-term borrowings-affiliated 99.0 (5.1 ) — — (113.1 ) (233.3 ) (252.5 ) Issuance of long-term debt 2,745.9 — — — — — 2,745.9 Debt related costs (27.9 ) 6.3 — — (2.0 ) — (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 ) — — — (959.6 ) — (2,807.8 ) Proceeds from the issuance of common units, net of offering costs — — 1,170.0 — (1.6 ) — 1,168.4 Issuance of common stock, net of offering costs 1,394.7 — — — — — 1,394.7 Contribution of capital from parent — — — — 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 — — — — (43.4 ) 43.4 — Distribution to noncontrolling interest in Columbia OpCo — — (187.3 ) — — 187.3 — Distribution received from Columbia OpCo — 187.3 — — — (187.3 ) — Distribution to noncontrolling interest — — — — — (23.2 ) (23.2 ) Dividends paid - common stock (79.5 ) — — — — — (79.5 ) Transfer from NiSource 0.9 (1.8 ) (34.8 ) — 36.5 — 0.8 Net Cash Flows from Financing Activities 834.9 1,404.0 447.9 — 595.3 (1,876.6 ) 1,405.5 Change in cash and cash equivalents 800.0 46.7 1.9 — 81.8 — 930.4 Cash and cash equivalents at beginning of period — — — — 0.5 — 0.5 Cash and Cash Equivalents at End of Period $ 800.0 $ 46.7 $ 1.9 $ — $ 82.3 $ — $ 930.9 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (continued) Year Ended December 31, 2014 (in millions) CPG CEG Columbia OpCo OpCo GP Non-guarantor Subsidiaries Consolidating adjustments and eliminations CPG Consolidated Net Cash Flows from Operating Activities $ — $ (3.7 ) $ — $ — $ 570.7 $ (2.2 ) $ 564.8 Investing Activities Capital expenditures — — — — (747.2 ) — (747.2 ) Insurance recoveries — — — — 11.3 — 11.3 Change in short-term lendings-affiliated — 4.8 — — (62.0 ) — (57.2 ) Proceeds from disposition of assets — — — — 9.3 — 9.3 Contributions to equity investees — — — — (69.2 ) — (69.2 ) Other investing activities — — — — (7.1 ) — (7.1 ) Net Cash Flows used for Investing Activities — 4.8 — — (864.9 ) — (860.1 ) Financing Activities Change in short-term borrowings-affiliated — 5.2 — — (472.3 ) — (467.1 ) Debt related costs — (6.3 ) — — (0.1 ) — (6.4 ) Issuance of long-term debt-affiliated — — — — 768.9 — 768.9 Distribution to parent — — — — (2.2 ) 2.2 — Net Cash Flows from Financing Activities — (1.1 ) — — 294.3 2.2 295.4 Change in cash and cash equivalents — — — — 0.1 — 0.1 Cash and cash equivalents at beginning of period — — — — 0.4 — 0.4 Cash and Cash Equivalents at End of Period $ — $ — $ — $ — $ 0.5 $ — $ 0.5

Nature of Operations and Summ55

Nature of Operations and Summary of Significant Accounting Policies (Narrative) (Details) $ / shares in Units, shares in Millions, $ in Millions	Feb. 17, 2017USD ($)$ / shares	Jul. 01, 2016USD ($)$ / shares	Dec. 31, 2016USD ($)ami$ / shares	Dec. 31, 2015USD ($)$ / shares	Dec. 31, 2014USD ($)	Jul. 01, 2015shares	May 22, 2015USD ($)
Basis Of Accounting Presentation [Line Items]
Pipeline Length | mi			15,000
Common Stock, Shares, Issued | shares						317.6
Senior Notes							$ 2,722.3
Repayments of Related Party Debt				$ 1,087.3
Distribution to Parent			$ 0	$ 1,450	$ 0
Business Acquisition, Effective Date of Acquisition		Jul. 1, 2016
Business Combination, Consideration Transferred		$ 13,000
Payments to Acquire Businesses, Gross		10,300
Noncash or Part Noncash Acquisition, Debt Assumed		$ 2,700
Common Stock, Par or Stated Value Per Share | $ / shares		$ 0.01	$ 0.01	$ 0.01
Business Acquisition, Share Price | $ / shares		$ 25.50
Merger related transaction costs			$ 66.6
Employee related Merger transaction costs			104.9
Impairment of long-lived assets			26.1	$ 2.4	0
Base Gas Purchases			0	0	0
Amortized software costs			20.4	8.7	4.3
Unamortized software costs			72.1	59.8
Goodwill			$ 1,975.5	1,975.5
Acres | a			460,000
Royalty Revenue			$ 21.5	26.5	43.8
Gain on Conveyances			16.9	52.3	34.5
Allocated Tax Benefit			0	$ 5.8	$ 1.3
Capitalized Exploratory Well Costs that Have Been Capitalized for Period Greater than One Year			$ 0.3
Projects that have Exploratory Well Costs that have been Capitalized for Period Greater than One Year, Number of Projects			1
Pennant
Basis Of Accounting Presentation [Line Items]
Equity Method Investment, Initial Ownership Percentage			5.00%
Cash Received from Buy-In			$ 12.7
Gain on Buy-In			$ 2.9
Previous | Pennant
Basis Of Accounting Presentation [Line Items]
Equity Method Investment, Ownership Percentage				47.50%	50.00%
Maximum | Pennant
Basis Of Accounting Presentation [Line Items]
Equity Method Investment, Ownership Percentage			33.33%
LLC Membership | Millennium Pipeline
Basis Of Accounting Presentation [Line Items]
Equity Method Investment, Ownership Percentage			47.50%
LLC Membership | Hardy Storage
Basis Of Accounting Presentation [Line Items]
Equity Method Investment, Ownership Percentage			50.00%
LLC Membership | Pennant
Basis Of Accounting Presentation [Line Items]
Equity Method Investment, Ownership Percentage			47.00%
Subsequent Event
Basis Of Accounting Presentation [Line Items]
Payments to Acquire Businesses, Gross	$ 915
Distribution Made to Limited Partner, Distributions Paid, Per Unit | $ / shares	$ 0.1975

Nature of Operations and Summ56

Nature of Operations and Summary of Significant Accounting Policies (Schedule of AFUDC Debt and Equity Rates) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Columbia Gas Transmission | Debt Rate
Schedule of AFUDC Debt and Equity Rates [Line Items]
Public Utilities, Allowance for Funds Used During Construction, Rate	0.60%	1.80%	0.90%
Columbia Gas Transmission | Equity Rate
Schedule of AFUDC Debt and Equity Rates [Line Items]
Public Utilities, Allowance for Funds Used During Construction, Rate	4.80%	6.30%	3.00%
Columbia Gulf | Debt Rate
Schedule of AFUDC Debt and Equity Rates [Line Items]
Public Utilities, Allowance for Funds Used During Construction, Rate	0.60%	2.90%	2.10%
Columbia Gulf | Equity Rate
Schedule of AFUDC Debt and Equity Rates [Line Items]
Public Utilities, Allowance for Funds Used During Construction, Rate	3.70%	6.30%	9.40%

Nature of Operations and Summ57

Nature of Operations and Summary of Significant Accounting Policies (Schedule of Changes in Capitalized Exploratory Well Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Beginning Balance	$ 1.7	$ 14.9
Capitalized Exploratory Well Cost, Additions Pending Determination of Proved Reserves	0	1.3
Reclassification to Well, Facilities, and Equipment Based on Determination of Proved Reserves	(1.3)	(14.5)
Ending Balance	$ 0.4	$ 1.7

CPPL Initial Public Offering (N

CPPL Initial Public Offering (Narrative) (Details) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)shares
Initial Public Offering [Line Items]
Issuance of common units of CPPL	$ 0
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
Noncontrolling Interest | Common Units
Initial Public Offering [Line Items]
Partners' Capital Account, Units, Sold in Public Offering | shares	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								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Initial Public Offering [Line Items]
Net Income Attributable to CPG	$ 58.2	$ (52.5)	$ 38.9	$ 72.2	$ 63.4	$ 63	$ 50.8	$ 90	$ 116.8	$ 267.2	$ 268.1
Increase for sale of limited partner interest									0	227.1
Change from net income attributable to parent and transfers to noncontrolling interest									$ 116.8	$ 494.3

Recent Accounting Pronounceme60

Recent Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 9.9
Unamortized debt issuance costs	$ 18	$ 20.6
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 20.6

Transactions with Affiliates (N

Transactions with Affiliates (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jun. 30, 2015
Related Party Transaction [Line Items]
Accounts receivable	$ 55.8	$ 0
Accounts payable-affiliated	4	0
Dividend to TransCanada	110.5
Short-term borrowings-affiliated	0	0
Transportation revenues-affiliated	0	47.5	$ 95.7
Storage revenues-affiliated	0	26.2	53.2
Other revenues		0.2	0.3
Operation and maintenance-affiliated	0	52.9	123.2
Interest Expense, Long-term Debt-affiliated		31	61.6
Allowance for Funds Used During Construction, Capitalized Interest		2.4	2.7
Distribution to Parent	0	1,450	0
Columbia OpCo
Related Party Transaction [Line Items]
Reimbursement of Preformation Capital		500
Money Pool
Related Party Transaction [Line Items]
Short-term Debt, Weighted Average Interest Rate				1.21%
Interest Expense, Short-term Borrowings-affiliated		$ 0.7	$ 3.1
TransCanada PipeLine USA Ltd.
Related Party Transaction [Line Items]
Interest Expense, Short-term Borrowings-affiliated	2.1
TransCanada PipeLine USA Ltd. | Revolving Credit Facility
Related Party Transaction [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 2,000
Short-term Debt, Weighted Average Interest Rate	1.98%
Short-term borrowings-affiliated	$ 0
Federal Funds Effective Swap Rate | TransCanada PipeLine USA Ltd.
Related Party Transaction [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%
London Interbank Offered Rate (LIBOR) | TransCanada PipeLine USA Ltd.
Related Party Transaction [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Margin Rate	0.25%
Eurodollar | TransCanada PipeLine USA Ltd.
Related Party Transaction [Line Items]
Margin Rate	1.25%

Short-Term Borrowings (Narrativ

Short-Term Borrowings (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)	Jun. 30, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 05, 2014USD ($)
Short-term Debt [Line Items]
Accelerated amortization of deferred costs	$ 5.7
Commercial Paper
Short-term Debt [Line Items]
Revolving credit facility, maximum borrowing capacity		$ 1,000
Commercial paper outstanding		$ 0	$ 0
Columbia Pipeline Partners LP | Revolving Credit Facility
Short-term Debt [Line Items]
Revolving credit facility, maximum borrowing capacity				$ 500
Letters of Credit Outstanding, Amount			0
Accelerated amortization of deferred costs	1.4
Line of Credit Facility, Amount Outstanding			$ 15
Short-term Debt, Weighted Average Interest Rate			1.28%
Columbia Pipeline Partners LP | Letter of Credit
Short-term Debt [Line Items]
Revolving credit facility, maximum borrowing capacity				50
New Revolving Credit Facility | Revolving Credit Facility
Short-term Debt [Line Items]
Revolving credit facility, maximum borrowing capacity	1,000
Line of Credit Facility, Amount Outstanding	$ 0
New Revolving Credit Facility | Minimum
Short-term Debt [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.04%
Ratio of Indebtedness to Net Capital	1
New Revolving Credit Facility | Maximum
Short-term Debt [Line Items]
Line of Credit Facility, Commitment Fee Percentage	0.15%
Ratio of Indebtedness to Net Capital	0.7500
New Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Minimum
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.75%
New Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Maximum
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.25%
New Revolving Credit Facility | Base Rate | Minimum
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%
New Revolving Credit Facility | Base Rate | Maximum
Short-term Debt [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.25%
Previous Revolving Credit Facility | Revolving Credit Facility
Short-term Debt [Line Items]
Revolving credit facility, maximum borrowing capacity				1,500
Accelerated amortization of deferred costs	$ 4.3
Line of Credit Facility, Amount Outstanding			$ 0
Previous Revolving Credit Facility | Letter of Credit
Short-term Debt [Line Items]
Revolving credit facility, maximum borrowing capacity				$ 250
Letters of Credit Outstanding, Amount			$ 18.1

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions	May 22, 2015	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount		$ 3.4
Unamortized Debt Issuance Expense		18	$ 20.6
Senior Notes
Debt Instrument [Line Items]
Face amount of notes		$ 2,750
Debt Instrument, Issuance Date	May 22, 2015
Notes Due 2018 | Senior Notes
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 | Senior Notes
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 | Senior Notes
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 | Senior Notes
Debt Instrument [Line Items]
Face amount of notes	$ 500
Debt Instrument, Interest Rate, Stated Percentage	5.80%
Debt Instrument, Maturity Date	Jun. 1, 2045

Long-Term Debt (Schedule Of Out

Long-Term Debt (Schedule Of Outstanding Long Term Debt Maturities) (Details) $ in Millions	Dec. 31, 2016USD ($)
Debt Instrument [Line Items]
2,017	$ 0
2,018	500
2,019	0
2,020	750
2,021	0
After	1,500
Total long-term debt	$ 2,750	[1]
[1]	This amount excludes unamortized discount and unamortized debt issuance costs of $3.4 million and $18.0 million, respectively. The unamortized discount and unamortized debt issuance costs applicable to the Notes are being amortized over the weighted average life of the Notes.

Gain on Sale of Assets (Details

Gain on Sale of Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Gain On Sale of Assets [Abstract]
Gain on Conveyances	$ 16.9	$ 52.3	$ 34.5
Gain on Conveyances Cash Received	9	35.8
Deferred Gains On Conveyances	$ 0.3	$ 8.1

Property, Plant and Equipment66

Property, Plant and Equipment (Schedule Of Property, Plant And Equipment) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	$ 10,461.2	$ 9,052.3
Accumulated Depreciation and Amortization	(3,126.2)	(2,988.6)
Net Property, Plant and Equipment	7,335	6,063.7
Pipeline and Other Transmission Assets
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	6,681.2	6,160.4
Storage Facilities
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	1,415.3	1,370.1
Gas Stored Base Gas
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	299.5	299.5
Gathering and Processing Facilities
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	566.9	370.2
Construction Work In Process
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	1,097	487.6
General Plant, Software, and Other Assets
Property, Plant and Equipment [Line Items]
Property Plant and Equipment	$ 401.3	$ 364.5

Property, Plant and Equipment67

Property, Plant and Equipment (Schedule of Depreciation Rates) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pipeline and Other Transmission Assets | Minimum
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	1.00%	1.00%	1.00%
Pipeline and Other Transmission Assets | Maximum
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	2.50%	2.50%	2.50%
Storage Facilities | Minimum
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	2.19%	2.19%	2.19%
Storage Facilities | Maximum
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	3.00%	3.00%	3.30%
Gathering and Processing Facilities | Minimum
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	1.67%	1.67%	1.67%
Gathering and Processing Facilities | Maximum
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	2.50%	2.50%	2.50%
General Plant, Software, and Other Assets | Minimum
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	1.00%	1.00%	1.00%
General Plant, Software, and Other Assets | Maximum
Property, Plant and Equipment [Line Items]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	20.00%	21.00%	10.00%

Goodwill (Narrative) (Details)

Goodwill (Narrative) (Details) - USD ($) $ in Millions	May 01, 2012	Dec. 31, 2016	Dec. 31, 2015
Goodwill And Other Intangible Assets [Line Items]
Goodwill		$ 1,975.5	$ 1,975.5
Columbia Gas Transmission
Goodwill And Other Intangible Assets [Line Items]
Fair Value Inputs, Discount Rate	5.60%
Fair value amount above carrying value of goodwill	$ 1,643

Asset Retirement Obligations (C

Asset Retirement Obligations (Changes In Company's Liability For Asset Retirement Obligations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Asset Retirement Obligation [Abstract]
Beginning Balance	$ 25.7	$ 23.2
Accretion expense	1.1	1.2
Additions	0	4.1
Change in estimated cash flows	(6)	(2.8)
Ending Balance	$ 20.8	$ 25.7

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions	Jan. 31, 2017	Jan. 01, 2016	Jan. 24, 2013	Dec. 31, 2016	Mar. 17, 2016
Regulatory Matters [Line Items]
Regulatory asset not earning return on investment				$ 0
Expenses recovered as components of cost of service and regulatory orders				$ 58.9
Remaining life for the costs to be recovered, years				6 years
MOD I Settlement
Regulatory Matters [Line Items]
Customer Refund			$ 88.1
Initial Customer Refund			50
Total Capital Cost Recovery Mechanism Over Five-year Term			$ 1,500
Depreciation Rate Reduction			1.50%
Annual base rate reduction effective January 1, 2014			$ 25
Capital Cost Recovery Mechanism Revenue Requirement			14.00%
Required Annual Capital Maintenance Expenditure			$ 100
Annual Capital Cost Recovery Mechanism Limit			$ 1,500
Program To Date Modernization Investment		$ 300
Annual Capital Cost Recovery Mechanism Limit Tolerance			15.00%
MOD I Settlement | Subsequent Event
Regulatory Matters [Line Items]
Annual Modernization Spend	$ 330
Program To Date Modernization Investment	$ 1,300
MOD II Settlement
Regulatory Matters [Line Items]
Total Capital Cost Recovery Mechanism Over Three-year term					$ 1,100
Base Rate Reduction					60
Annual OPEB Reduction					8.4
OPEB Over-collection Reduction					12.4
Rate reset annual reduction					7.5
One-time settlement payment					$ 5
Revenue sharing percentage					50.00%
Transmission depreciation rate					1.50%
Storage depreciation rate					2.20%
Negative Salvage Depreciation Rate					0.00%

Regulatory Matters (Regulatory

Regulatory Matters (Regulatory Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Regulatory Assets [Line Items]
Total Assets	$ 176.9	$ 182.7
Unrecognized Pension Benefit And Other Postretirement Benefit Costs
Regulatory Assets [Line Items]
Total Assets	111.3	135.2
Other Postretirement Costs
Regulatory Assets [Line Items]
Total Assets	6.3	9
Deferred Taxes on AFUDC Equity
Regulatory Assets [Line Items]
Total Assets	57	35.4
Other
Regulatory Assets [Line Items]
Total Assets	$ 2.3	$ 3.1

Regulatory Matters (Regulator72

Regulatory Matters (Regulatory Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Regulatory Liabilities [Line Items]
Total Liabilities	$ 293.4	$ 322.8
Cost Of Removal
Regulatory Liabilities [Line Items]
Total Liabilities	141.5	154.7
Regulatory Effects Of Accounting For Income Taxes
Regulatory Liabilities [Line Items]
Total Liabilities	10.2	10.6
Modernization Revenue Sharing
Regulatory Liabilities [Line Items]
Total Liabilities	7.4	0
Other Postretirement Costs
Regulatory Liabilities [Line Items]
Total Liabilities	134.3	155.6
Other
Regulatory Liabilities [Line Items]
Total Liabilities	$ 0	$ 1.9

Equity Method Investments (Narr

Equity Method Investments (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Operation and maintenance	$ 863.2	$ 652.1	$ 628.4
Millennium Pipeline
Schedule of Equity Method Investments [Line Items]
Operation and maintenance	$ 10.5	$ 13.1

Equity Method Investments (Sche

Equity Method Investments (Schedule Of Equity Method Investments) (Details) - LLC Membership	Dec. 31, 2016
Hardy Storage Company, LLC
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Pennant Midstream, LLC
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	47.00%
Millennium Pipeline, L.L.C.
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	47.50%

Equity Method Investments (Sc75

Equity Method Investments (Schedule Of Immaterial Nature Of Equity Investments) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Millennium Pipeline
Schedule of Equity Method Investments [Line Items]
Net Revenues		$ 205	$ 206.3	$ 190.5
Operating Income		138.1	136.1	128.8
Net Income		102.5	98	89.6
Current Assets		34.8	35.7	32.1
Noncurrent Assets		969.8	987.1	1,016.3
Current Liabilities		48	44.4	42.6
Noncurrent Liabilities		497.2	535.8	568.3
Total Members' Equity		459.4	442.6	437.5
Contributions	[1]	6.2	1.4	2.6
Distribution of Earnings	[1]	48.9	47.5	35.6
Hardy Storage
Schedule of Equity Method Investments [Line Items]
Net Revenues		23.5	23.4	23.6
Operating Income		15.7	15.3	16.1
Net Income		11.2	10.3	10.6
Current Assets		10.3	12.1	12
Noncurrent Assets		151.3	155.5	157.4
Current Liabilities		17.2	19.3	17.1
Noncurrent Liabilities		57.5	68.5	77.4
Total Members' Equity		86.9	79.8	74.9
Contributions	[1]	0	0	0
Distribution of Earnings	[1]	2	2.6	2.2
Pennant
Schedule of Equity Method Investments [Line Items]
Net Revenues		38.2	34.6	8.5
Operating Income		21.2	17.8	(2.4)
Net Income		21.2	17.8	(2.4)
Current Assets		9.8	11	23.7
Noncurrent Assets		384	389.6	380
Current Liabilities		3.5	8.4	8.6
Total Members' Equity		390.3	392.2	395.1
Contributions	[1]	0	0	66.6
Distribution of Earnings	[1]	10.6	7.1	0
Return of Capital	[1]	$ 2.2	$ 16	$ 0
[1]	Contribution and distribution data represents CPG's portion based on CPG's ownership percentage of each investment.

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax [Line Items]
Effective income tax rates	33.60%	33.20%	38.70%
Increase (Decrease) in Effective Tax Rate		(5.50%)
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 9.9
Remaining carry forwards	$ 211.5
Tax Credit Carryforward, Expiration Date	Dec. 31, 2036
Expected benefits to be realized	$ 20.2
Unrecognized tax benefits, if recognized, would affect effective tax rate	0	$ (0.4)	$ 0
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	$ 0	$ 0	$ 0
2015-2017
Income Tax [Line Items]
Bonus Depreciation Phase Down Rate	50.00%
2,018
Income Tax [Line Items]
Bonus Depreciation Phase Down Rate	40.00%
2,019
Income Tax [Line Items]
Bonus Depreciation Phase Down Rate	30.00%

Income Taxes (Schedule Of Compo

Income Taxes (Schedule Of Components Of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal income taxes	$ (55.7)	$ 12.1	$ 19.5
Current state income taxes	4.2	9.1	7.6
Total current income taxes	(51.5)	21.2	27.1
Deferred federal income taxes	116.3	120.2	119.2
Deferred state income taxes	13	11.6	23.5
Total deferred income taxes	129.3	131.8	142.7
Deferred Investment Credits	0	0	(0.1)
Income Taxes from Continuing Operations	$ 77.8	$ 153	$ 169.7

Income Taxes (Schedule Of Reaso

Income Taxes (Schedule Of Reasons Behind Differences In Computation Of Total Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest	$ 231.5	$ 460.5	$ 438.4
Tax expense at statutory federal income tax rate, value	81	161.2	153.5
State income taxes, net of federal income tax benefit, value	11.2	13.4	20.3
Regulatory treatment of depreciation differences, value	(13)	(14)	0
Regulatory treatment of AFUDC-Equity, value	(11.2)	(9.2)	(3.7)
Effective income tax rate reconciliation, Transaction Cost, Amount	8.7	0	0
Tax accrual adjustments and other, net, value	1.1	1.6	(0.4)
Income Taxes from Continuing Operations	$ 77.8	$ 153	$ 169.7
Tax expense at statutory federal income tax rate, rate	35.00%	35.00%	35.00%
State income taxes, net of federal income tax benefit, rate	4.80%	2.90%	4.60%
Regulatory treatment of depreciation differences, rate	(5.60%)	(3.00%)	0.00%
Regulatory treatment of AFUDC-Equity, rate	(4.80%)	(2.00%)	(0.80%)
Effective income tax rate reconciliation, Transaction Cost, Percent	3.80%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent	0.40%	0.30%	(0.10%)
Income Taxes from Continuing Operations, rate	33.60%	33.20%	38.70%

Income Taxes (Schedule Of Princ

Income Taxes (Schedule Of Principal Components Of Net Deferred Tax Liability) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Accelerated depreciation and other property differences	$ 1,625.8	$ 1,429.2
Pension and Other Postretirement/Postemployment Benefits	31.1	29.9
Other regulatory assets	67.8	71.8
Equity Method Investments	130.2	124.3
Total Deferred Tax Liabilities	1,854.9	1,655.2
Other regulatory liabilities	(104.9)	(126.8)
Net operating loss carryforward	(231.7)	(141.4)
Other	(17.9)	(38.9)
Total Deferred Tax Assets	(354.5)	(307.1)
Net Deferred Tax Liabilities	$ 1,500.4	$ 1,348.1

Pension and Other Postretirem80

Pension and Other Postretirement Benefits (Narrative) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets			$ 579.8	$ 586
Regulatory assets			176.9	182.7
Regulatory liabilities			293.4	322.8
Increase In Net Periodic Benefit Cost			18.3
Defined Benefit Plan, Accumulated Benefit Obligation			375.7	404.5
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets			348.1	357.8	$ 351
Employer contributions			8.4	20
Expected contribution			0
Funded status of plan			27.6	46.7
Settlements			12.3	0	0
Defined Benefit Plan, Net Periodic Benefit Cost			$ 19.8	$ 1.5	$ (0.4)
Expected return on plan assets			7.29%	8.20%	8.30%
Defined Benefit Plan, Actuarial Gain (Loss)	[1]		$ (4.7)	$ (6.9)
Amortization of prior service cost			(1.2)	(1.1)	$ (1.1)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets			231.3	228.2	223.8
Employer contributions			0.3	13.5
Expected contribution			1.9
Funded status of plan			(122.2)	(116.1)
Increase in funded status other postretirement benefit plans			6.1
Settlements			0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost			$ (10)	$ (13)	$ (10.8)
Expected return on plan assets			6.81%	8.05%	8.14%
Defined Benefit Plan, Actuarial Gain (Loss)	[1]		$ 2.1	$ (12.4)
Amortization of prior service cost			(0.7)	(0.3)	$ 0.1
Unrecognized Pension Benefit And Other Postretirement Benefit Costs
Defined Benefit Plan Disclosure [Line Items]
Regulatory liabilities			0	0.7
Scenario, Forecast | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss)		$ 10
Amortization of prior service cost		(1.2)
Amortization of transition obligation		0
Scenario, Forecast | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss)		0.5
Amortization of prior service cost		(0.7)
Amortization of transition obligation		$ 0
Unrecognized Pension Benefit And Other Postretirement Benefit Costs
Defined Benefit Plan Disclosure [Line Items]
Regulatory assets			111.3	135.2
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets			0	0	$ 17.6
Significant Unobservable Inputs (Level 3) | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets			$ 0	$ 0
[1]	The change in benefit obligation for Pension Benefits represents the change in Projected Benefit Obligation while the change in benefit obligation for Other Postretirement Benefits represents the change in Accumulated Postretirement Benefit Obligation.

Pension and Other Postretirem81

Pension and Other Postretirement Benefits (Schedule Of Portfolio Asset Mix) (Details)	12 Months Ended
	Dec. 31, 2016
Domestic Equities | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Equities, Minimum	35.00%
Equities, Maximum	55.00%
Domestic Equities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Equities, Minimum	35.00%
Equities, Maximum	55.00%
International Equities | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Equities, Minimum	10.00%
Equities, Maximum	20.00%
International Equities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Equities, Minimum	15.00%
Equities, Maximum	25.00%
Fixed Income | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Equities, Minimum	30.00%
Equities, Maximum	50.00%
Fixed Income | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Equities, Minimum	20.00%
Equities, Maximum	50.00%
Short-Term Investments | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Equities, Minimum	0.00%
Equities, Maximum	10.00%
Short-Term Investments | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Equities, Minimum	0.00%
Equities, Maximum	10.00%

Pension and Other Postretirem82

Pension and Other Postretirement Benefits (Schedule Of Pension Plan And Postretirement Plan Asset Mix) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	$ 579.8	$ 586
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Percentage of total asset	100.00%	100.00%
Fair value of asset	$ 348.1	$ 357.8	$ 351
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Percentage of total asset	100.00%	100.00%
Fair value of asset	$ 231.3	$ 228.2	$ 223.8
Domestic Equities | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Percentage of total asset	42.70%	39.40%
Fair value of asset	$ 148.7	$ 141
Domestic Equities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Percentage of total asset	41.50%	44.40%
Fair value of asset	$ 95.9	$ 101.6
International Equities | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Percentage of total asset	16.20%	17.50%
Fair value of asset	$ 56.3	$ 62.5
International Equities | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Percentage of total asset	18.80%	18.80%
Fair value of asset	$ 43.4	$ 42.8
Fixed Income | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Percentage of total asset	39.20%	34.40%
Fair value of asset	$ 136.3	$ 123.3
Fixed Income | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Percentage of total asset	33.20%	33.60%
Fair value of asset	$ 76.9	$ 76.6
Cash/Other | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Percentage of total asset	1.90%	8.70%
Fair value of asset	$ 6.8	$ 31
Cash/Other | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Percentage of total asset	6.50%	3.20%
Fair value of asset	$ 15.1	$ 7.2

Pension and Other Postretirem83

Pension and Other Postretirement Benefits (Schedule Of Fair Value Of Pension Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Net Asset Value Excluded From Fair Value Input	$ 244.9		$ 349.8
Fair value of asset	(579.8)		(586)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	0		0
Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(306.2)		(214.5)
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(28.3)		(21.5)
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0		$ (17.6)
Due to brokers, net
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(0.2)	[1]	(0.4)	[2]
Accrued Investment Income Dividends
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	$ (0.6)		$ (0.6)
Commingled Funds | United States Equities
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	1 day		3 days
Net Asset Value Excluded From Fair Value Input	$ 94.1		$ 154.9
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	$ 0		$ 0
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	Daily		Monthly
Commingled Funds | International Equities
Defined Benefit Plan Disclosure [Line Items]
Net Asset Value Excluded From Fair Value Input	$ 56.3		$ 55.6
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	$ 0		$ 0
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	Daily		Monthly
Commingled Funds | Short-Term Money Markets
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	1 day		1 day
Net Asset Value Excluded From Fair Value Input	$ 21.3		$ 38.4
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	$ 0		$ 0
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	Daily		Daily
Commingled Funds | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	2 days		3 days
Net Asset Value Excluded From Fair Value Input	$ 73.2		$ 100.9
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments	$ 0		$ 0
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency	Daily		Monthly
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	$ (348.1)		$ (357.8)		(351)
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items	348.1		357.6
Pension Plan | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items	90.6		7.5
Pension Plan | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items	28.3		21.5
Pension Plan | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Fair Value Of Plan Assets Before Pending Items	0		0
Pension Plan | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(0.2)		(0.9)
Pension Plan | Cash | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(0.2)		(0.9)
Pension Plan | Cash | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Pension Plan | Cash | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Pension Plan | International Equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(56.3)		(62.5)
Pension Plan | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(136.3)		(123.3)
Pension Plan | Equity Securities | International Equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset			(6.6)
Pension Plan | Equity Securities | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset			(6.6)
Pension Plan | Equity Securities | International Equities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset			0
Pension Plan | Equity Securities | International Equities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset			0
Pension Plan | Fixed Income Securities | Government
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(8.8)		(8.5)
Pension Plan | Fixed Income Securities | Government | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Pension Plan | Fixed Income Securities | Government | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(8.8)		(8.5)
Pension Plan | Fixed Income Securities | Government | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Pension Plan | Fixed Income Securities | Corporate
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(19.5)		(13)
Pension Plan | Fixed Income Securities | Corporate | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Pension Plan | Fixed Income Securities | Corporate | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(19.5)		(13)
Pension Plan | Fixed Income Securities | Corporate | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Pension Plan | Commingled Funds | United States Equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(93.1)	[3]	(141)	[4]
Pension Plan | Commingled Funds | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Pension Plan | Commingled Funds | United States Equities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Pension Plan | Commingled Funds | United States Equities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Pension Plan | Commingled Funds | International Equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(56.3)	[3]	(55.6)	[4]
Pension Plan | Commingled Funds | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Pension Plan | Commingled Funds | International Equities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Pension Plan | Commingled Funds | International Equities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Pension Plan | Commingled Funds | Short-Term Money Markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(6.6)	[3]	(31.1)	[4]
Pension Plan | Commingled Funds | Short-Term Money Markets | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Pension Plan | Commingled Funds | Short-Term Money Markets | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Pension Plan | Commingled Funds | Short-Term Money Markets | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Pension Plan | Commingled Funds | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(73.2)	[3]	(100.9)	[4]
Pension Plan | Commingled Funds | Fixed Income | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Pension Plan | Commingled Funds | Fixed Income | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Pension Plan | Commingled Funds | Fixed Income | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Pension Plan | Mutual Funds | U.S. Multi-Strategy
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(55.6)
Pension Plan | Mutual Funds | U.S. Multi-Strategy | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(55.6)
Pension Plan | Mutual Funds | U.S. Multi-Strategy | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0
Pension Plan | Mutual Funds | U.S. Multi-Strategy | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0
Pension Plan | Mutual Funds | International Multi-Strategy
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(34.8)
Pension Plan | Mutual Funds | International Multi-Strategy | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(34.8)
Pension Plan | Mutual Funds | International Multi-Strategy | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0
Pension Plan | Mutual Funds | International Multi-Strategy | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(231.3)		(228.2)		$ (223.8)
Other Postretirement Benefits | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(215.6)		(207)
Other Postretirement Benefits | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Other Postretirement Benefits | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Other Postretirement Benefits | Cash
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(0.4)
Other Postretirement Benefits | Cash | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(0.4)
Other Postretirement Benefits | Cash | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0
Other Postretirement Benefits | Cash | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0
Other Postretirement Benefits | International Equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(43.4)		(42.8)
Other Postretirement Benefits | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(76.9)		(76.6)
Other Postretirement Benefits | Commingled Funds | United States Equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(1)	[3]	(13.9)	[4]
Other Postretirement Benefits | Commingled Funds | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Other Postretirement Benefits | Commingled Funds | United States Equities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Other Postretirement Benefits | Commingled Funds | United States Equities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(14.7)	[3]	(7.3)	[4]
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Other Postretirement Benefits | Commingled Funds | Short-Term Money Markets | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset
Other Postretirement Benefits | Mutual Funds | United States Equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(94.9)		(87.7)
Other Postretirement Benefits | Mutual Funds | United States Equities | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(94.9)		(87.7)
Other Postretirement Benefits | Mutual Funds | United States Equities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Other Postretirement Benefits | Mutual Funds | United States Equities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Other Postretirement Benefits | Mutual Funds | International Equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(43.4)		(42.8)
Other Postretirement Benefits | Mutual Funds | International Equities | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(43.4)		(42.8)
Other Postretirement Benefits | Mutual Funds | International Equities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Other Postretirement Benefits | Mutual Funds | International Equities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Other Postretirement Benefits | Mutual Funds | Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(76.9)		(76.5)
Other Postretirement Benefits | Mutual Funds | Fixed Income | Quoted Prices In Active Markets For Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	(76.9)		(76.5)
Other Postretirement Benefits | Mutual Funds | Fixed Income | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	0		0
Other Postretirement Benefits | Mutual Funds | Fixed Income | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of asset	$ 0		$ 0
Minimum | Commingled Funds | International Equities
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	2 days		14 days
Maximum | Commingled Funds | International Equities
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period	3 days		30 days
[1]	This class represents pending trades with brokers.
[2]	This class represents pending trades with brokers.
[3]	This class of investments is measured at fair value using the net asset value per share and has not been classified in the fair value hierarchy.
[4]	This class of investments is measured at fair value using the net asset value per share and has not been classified in the fair value hierarchy.

Pension and Other Postretirem84

Pension and Other Postretirement Benefits (Schedule Of Changes In The Fair Value Of The Plan Level Three Assets) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at end of year	$ 586
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	17.6
Total gains or losses (unrealized / realized)	0
Purchases	0
(Sales)	0
Transfers into/(out of) level 3	0
Separation Allocation	(17.6)	[1]
Fair value of plan assets at end of year	0
Real Estate | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	2.6
Total gains or losses (unrealized / realized)	0
Purchases	0
(Sales)	0
Transfers into/(out of) level 3	0
Separation Allocation	(2.6)	[1]
Fair value of plan assets at end of year	0
Fixed Income Securities | Other Fixed Income | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	0.1
Total gains or losses (unrealized / realized)	0
Purchases	0
(Sales)	0
Transfers into/(out of) level 3	0
Separation Allocation	(0.1)	[1]
Fair value of plan assets at end of year	0
Private Equity Limited Partnerships | U.S. Multi-Strategy | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	8.5
Total gains or losses (unrealized / realized)	0
Purchases	0
(Sales)	0
Transfers into/(out of) level 3	0
Separation Allocation	(8.5)	[1]
Fair value of plan assets at end of year	0
Private Equity Limited Partnerships | International Multi-Strategy | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	5.3
Total gains or losses (unrealized / realized)	0
Purchases	0
(Sales)	0
Transfers into/(out of) level 3	0
Separation Allocation	(5.3)	[1]
Fair value of plan assets at end of year	0
Private Equity Limited Partnerships | Distressed Opportunities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	1.1
Total gains or losses (unrealized / realized)	0
Purchases	0
(Sales)	0
Transfers into/(out of) level 3	0
Separation Allocation	(1.1)	[1]
Fair value of plan assets at end of year	$ 0
[1]	Level 3 assets were not contributed to the CPG Plans upon Separation from NiSource and no subsequent investments were made in Level 3 assets post Separation.

Pension and Other Postretirem85

Pension and Other Postretirement Benefits (Schedule Of Reconciliation Of The Plans Funded Status And Amounts Reflected) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year		$ 586
Fair value of plan assets at end of year		579.8		$ 586
Postretirement and postemployment benefits assets		121.8		115.7
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	[1]	404.5		397.6
Service cost		6.4	[1]	5.9	[1]	$ 4.8
Interest cost		15.1	[1]	15	[1]	15.7
Plan participants' contributions	[1]	0		0
Actuarial loss (gain)	[1]	(4.7)		(6.9)
Defined Benefit Plan Settlement Loss	[1]	3.2		0
Benefits paid	[1]	(48.8)		(29.7)
Estimated benefits paid by incurred subsidy	[1]	0		0
Transfer of Participant Balances from NiSource Plans	[1],[2]	0		22.6
Transfer of Participant Balances, Plan Assets	[2]	0		15.3
Projected benefit obligation at end of year	[1]	375.7		404.5		397.6
Fair value of plan assets at beginning of year		357.8		351
Actual return on plan assets		30.7		1.2
Employer contributions		8.4		20
Fair value of plan assets at end of year		348.1		357.8		351
Funded Status at end of year		(27.6)		(46.7)
Postretirement and postemployment benefits assets		0		0
Current liabilities		0		(0.8)
Noncurrent liabilities		(27.6)		(45.9)
Net amount recognized at end of year	[3]	(27.6)		(46.7)
Unrecognized prior service cost	[4]	(2.6)		(3.7)
Unrecognized actuarial loss	[4]	133		164.5
Defined Benefit Plan Amounts Recognized In Other Comprehensive Income Or Regulatory Asset Or Liability	[4]	130.4		160.8
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation at beginning of year	[1]	112.1		124.2
Service cost		0.9	[1]	1	[1]	1.1
Interest cost		4.5	[1]	4.7	[1]	4.6
Plan participants' contributions	[1]	2.8		2.3
Actuarial loss (gain)	[1]	2.1		(12.4)
Defined Benefit Plan Settlement Loss	[1]	0		0
Benefits paid	[1]	(13.6)		(9.8)
Estimated benefits paid by incurred subsidy	[1]	0.3		0.3
Transfer of Participant Balances from NiSource Plans	[1],[2]	0		1.8
Transfer of Participant Balances, Plan Assets	[2]	0		0.9
Projected benefit obligation at end of year	[1]	109.1		112.1		124.2
Fair value of plan assets at beginning of year		228.2		223.8
Actual return on plan assets		13.6		(2.5)
Employer contributions		0.3		13.5
Fair value of plan assets at end of year		231.3		228.2		$ 223.8
Funded Status at end of year		122.2		116.1
Postretirement and postemployment benefits assets		122.2		116.1
Current liabilities		0		0
Noncurrent liabilities		0		0
Net amount recognized at end of year	[3]	122.2		116.1
Unrecognized prior service cost	[4]	(1.3)		(2)
Unrecognized actuarial loss	[4]	(0.7)		(3.9)
Defined Benefit Plan Amounts Recognized In Other Comprehensive Income Or Regulatory Asset Or Liability	[4]	$ (2)		$ (5.9)
[1]	The change in benefit obligation for Pension Benefits represents the change in Projected Benefit Obligation while the change in benefit obligation for Other Postretirement Benefits represents the change in Accumulated Postretirement Benefit Obligation.
[2]	Reflects the transfer of additional pension and OPEB plan participants to CPGSC upon Separation from NiSource that were determined in the current year.
[3]	CPG recognizes in its Consolidated Balance Sheets the underfunded and overfunded status of its various defined benefit postretirement plans, measured as the difference between the fair value of the plan assets and the benefit obligation.
[4]	CPG determined that the future recovery of pension and other postretirement benefits costs is probable. CPG recorded regulatory assets and liabilities of $111.3 million and zero, respectively, as of December 31, 2016, and $135.2 million and $0.7 million, respectively, as of December 31, 2015 that would otherwise have been recorded to accumulated other comprehensive loss.

Pension and Other Postretirem86

Pension and Other Postretirement Benefits (Schedule Of Significant Actuarial Assumptions In Determining Funded Status Plan) (Details)	Dec. 31, 2015	Dec. 31, 2016
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	4.05%	4.10%
Rate of Compensation Increases	4.00%	2.50%
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	4.29%	4.25%
Trend for Next Year	8.39%	8.47%
Ultimate Trend	4.50%	4.50%
Year Ultimate Trend Reached	2,022	2,024

Pension and Other Postretirem87

Pension and Other Postretirement Benefits (Schedule Of One-Percentage-Point Change In Assumed Health Care Cost Trend Rates) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Defined Benefit Plan Disclosure [Line Items]
Effect on service and interest components of net periodic cost, 1% point increase	$ 0.1
Effect on service and interest components of net periodic cost, 1% point decrease	(0.1)
Effect on accumulated postretirement benefit obligation, 1% point increase	2.6
Effect on accumulated postretirement benefit obligation, 1% point decrease	$ (2.4)

Pension and Other Postretirem88

Pension and Other Postretirement Benefits (Schedule Of Expected Payments To Participants In Pension Plan) (Details) $ in Millions	Dec. 31, 2016USD ($)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
2,017	$ 32.3
2,018	33.1
2,019	33.8
2,020	35.2
2,021	34.9
2022-2026	168.8
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
2,017	7.8
2,018	7.8
2,019	7.8
2,020	7.7
2,021	7.6
2022-2026	35.5
Postretirement Health Coverage
Defined Benefit Plan Disclosure [Line Items]
2,017	0.5
2,018	0.5
2,019	0.4
2,020	0.4
2,021	0.4
2022-2026	$ 1.2

Pension and Other Postretirem89

Pension and Other Postretirement Benefits (Components Of The Plans' Net Periodic Benefits Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 6.4	[1]	$ 5.9	[1]	$ 4.8
Interest cost	15.1	[1]	15	[1]	15.7
Expected return on assets	(25)		(28.2)		(27.3)
Amortization of prior service cost	(1.2)		(1.1)		(1.1)
Recognized actuarial loss	12.2		9.9		7.5
Net Periodic Benefit Costs	7.5		1.5		(0.4)
Settlement loss	12.3		0		0
Total Net Periodic Benefits Cost	19.8		1.5		(0.4)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service Cost	0.9	[1]	1	[1]	1.1
Interest cost	4.5	[1]	4.7	[1]	4.6
Expected return on assets	(15)		(18.1)		(16.6)
Amortization of prior service cost	(0.7)		(0.3)		0.1
Recognized actuarial loss	0.3		(0.3)		0
Net Periodic Benefit Costs	(10)		(13)		(10.8)
Settlement loss	0		0		0
Total Net Periodic Benefits Cost	$ (10)		$ (13)		$ (10.8)
[1]	The change in benefit obligation for Pension Benefits represents the change in Projected Benefit Obligation while the change in benefit obligation for Other Postretirement Benefits represents the change in Accumulated Postretirement Benefit Obligation.

Pension and Other Postretirem90

Pension and Other Postretirement Benefits (Schedule Of Key Assumptions That Were Used To Calculate The Net Periodic Benefits Cost) (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	3.90%	3.84%	4.34%
Expected Long-Term Rate of Return on Plan Assets	7.29%	8.20%	8.30%
Rate of Compensation Increases	4.00%	4.00%	4.00%
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	4.12%	4.10%	4.76%
Expected Long-Term Rate of Return on Plan Assets	6.81%	8.05%	8.14%

Pension and Other Postretirem91

Pension and Other Postretirement Benefits (Schedule Of Changes In Plan Assets And Projected Benefit Obligations Recognized In Other Comprehensive Income) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Plan
Settlements		$ 12.3	$ 0	$ 0
Net actuarial (gain)/loss	[1]	4.7	6.9
Amortization of prior service cost		1.2	1.1	1.1
Less: amortization of net actuarial (gain) loss		12.2	9.9	7.5
Other Postretirement Benefits
Settlements		0	0	0
Net actuarial (gain)/loss	[1]	(2.1)	12.4
Amortization of prior service cost		0.7	0.3	(0.1)
Less: amortization of net actuarial (gain) loss		0.3	(0.3)	$ 0
Other Comprehensive Income Or Regulatory Assets Or Liabilities | Pension Plan
Settlements		(12.3)	0
Net actuarial (gain)/loss		(7.1)	25.6
Amortization of prior service cost		(1.2)	(1.1)
Less: amortization of net actuarial (gain) loss		(12.2)	(9.9)
Total Recognized in Other Comprehensive Income or Regulatory Asset or Liability		(30.4)	16.8
Amount Recognized in Net Periodic Benefits Cost and Other Comprehensive Income or Regulatory Asset or Liability		(10.6)	18.3
Other Comprehensive Income Or Regulatory Assets Or Liabilities | Other Postretirement Benefits
Settlements		0	0
Net actuarial (gain)/loss		3.5	8.6
Amortization of prior service cost		(0.7)	(0.3)
Less: amortization of net actuarial (gain) loss		(0.3)	0.3
Total Recognized in Other Comprehensive Income or Regulatory Asset or Liability		3.9	9.2
Amount Recognized in Net Periodic Benefits Cost and Other Comprehensive Income or Regulatory Asset or Liability		$ (6.1)	$ (3.8)
[1]	The change in benefit obligation for Pension Benefits represents the change in Projected Benefit Obligation while the change in benefit obligation for Other Postretirement Benefits represents the change in Accumulated Postretirement Benefit Obligation.

Fair Value (Carrying Amount And

Fair Value (Carrying Amount And Estimated Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Long-term debt, carrying amount	[1]	$ 2,750	$ 2,750
Long-term debt, Estimated Fair Value		$ 2,868.8	$ 2,592.1
[1]	The carrying amount of the Notes differs from the Long-term debt balance on the Consolidated Balance Sheets 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	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jul. 01, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Business Acquisition, Share Price				$ 25.50
Stock-based employee compensation expense	$ 65.2	$ 7.9	$ 4.4
Related tax benefits	21.9	2.9	1.6
401(k) match, profit sharing and non-elective expense	$ 12.2	$ 9.8	$ 8.4
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	12,144
Shares nonvested	0	2,268,792
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	955,848
Shares nonvested	0	161,504
Omnibus Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Goods and Nonemployee Services Transaction, Nonvested, Number	0
Director Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Goods and Nonemployee Services Transaction, Nonvested, Number	0
2016 Award | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period, (years)	3 years
NiSource Plan | 2015 Award | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted		450,107
Fair value of shares granted		$ 11.6
Shares nonvested	0
NiSource Plan | 2014 Award | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted			198,532
Fair value of shares granted			$ 4.2
Shares nonvested	0
NiSource Plan | 2014 Award | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted			586,219
Fair value of shares granted			$ 11.3
Shares nonvested	0
CPG Plan | 2016 Award | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	12,144
Fair value of shares granted	$ 0.2
Shares nonvested	0
CPG Plan | 2016 Award | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	955,848
Fair value of shares granted	$ 17
Shares nonvested	0
CPG Plan | 2015 Award | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted		130,160
Fair value of shares granted		$ 3.6
Shares nonvested	0
CPG Plan | 2015 Award | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted		161,504
Fair value of shares granted		$ 4.5
Shares nonvested	0

Share-Based Compensation (Sched

Share-Based Compensation (Schedule Of Transactions Of Restricted Stock Unit) (Details) - Restricted Stock	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested at December 31, 2015 | shares	2,268,792
Granted | shares	12,144
Forfeited | shares	(22,590)
Vested | shares	(2,258,346)
Outstanding at December 31, 2016 | shares	0
Nonvested at December 31, 2015, Weighted Average Grant Date Fair Value | $ / shares	$ 18.85
Granted, Weighted Average Grant Date Fair Value | $ / shares	16.86
Forfeited, Weighted Average Grant Date Fair Value | $ / shares	22.71
Vested, Weighted Average Grant Date Fair Value | $ / shares	18.80
Outstanding at December 31, 2016, Weighted Average Grant Date Fair Value | $ / shares	$ 0

Share-Based Compensation (Sch95

Share-Based Compensation (Schedule Of Transactions Of Contingent Awards) (Details) - Performance Shares	12 Months Ended
	Dec. 31, 2016$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested at December 31, 2015 | shares	161,504
Granted | shares	955,848
Forfeited | shares	0
Vested | shares	(1,117,352)
Outstanding at December 31, 2016 | shares	0
Nonvested at December 31, 2015, Weighted Average Grant Date Fair Value | $ / shares	$ 28.16
Granted, Weighted Average Grant Date Fair Value | $ / shares	17.79
Forfeited, Weighted Average Grant Date Fair Value | $ / shares	0
Vested, Weighted Average Grant Date Fair Value | $ / shares	19.29
Outstanding at December 31, 2016, Weighted Average Grant Date Fair Value | $ / shares	$ 0

Other Commitments and Conting96

Other Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jun. 30, 2016	Dec. 05, 2014	Aug. 31, 2010
Other Commitments And Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	$ 7.8	$ 8.3
Payments made in connection with operating leases	23.9	21.2	$ 14.9
Former Propane and Petroleum Operations
Other Commitments And Contingencies [Line Items]
Liability for estimated remediation costs	6.3	6.5
PCB
Other Commitments And Contingencies [Line Items]
Liability for estimated remediation costs	1.5	1.8
Millennium Pipeline
Other Commitments And Contingencies [Line Items]
Face amount of notes						$ 725
Guarantee Type, Other
Other Commitments And Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	4.7
Revolving Credit Facility | Columbia Pipeline Partners LP
Other Commitments And Contingencies [Line Items]
Revolving credit facility, maximum borrowing capacity					$ 500
Credit facilities borrowings		15
Letters of Credit Outstanding, Amount		0
Commercial Paper
Other Commitments And Contingencies [Line Items]
Revolving credit facility, maximum borrowing capacity				$ 1,000
Commercial paper		0		$ 0
Letter of Credit | Columbia Pipeline Partners LP
Other Commitments And Contingencies [Line Items]
Revolving credit facility, maximum borrowing capacity					50
IBM Service Agreement
Other Commitments And Contingencies [Line Items]
Purchase And Service Obligations Minimum Fixed Payments Due	128.2
Senior Notes
Other Commitments And Contingencies [Line Items]
Face amount of notes	2,750
Previous Revolving Credit Facility | Revolving Credit Facility
Other Commitments And Contingencies [Line Items]
Revolving credit facility, maximum borrowing capacity					1,500
Credit facilities borrowings		0
Previous Revolving Credit Facility | Letter of Credit
Other Commitments And Contingencies [Line Items]
Revolving credit facility, maximum borrowing capacity					$ 250
Letters of Credit Outstanding, Amount		$ 18.1
New Revolving Credit Facility | Revolving Credit Facility
Other Commitments And Contingencies [Line Items]
Revolving credit facility, maximum borrowing capacity	1,000
Credit facilities borrowings	$ 0

Other Commitments and Conting97

Other Commitments and Contingencies (Existence And Expiration Of Commercial Commitments) (Details) - Guarantee Type, Other $ in Millions	Dec. 31, 2016USD ($)
Other Commitments And Contingencies [Line Items]
2,017	$ 2.2
2,018	0
2,019	0
2,020	0
2,021	0
Thereafter	2.5
Total	$ 4.7

Other Commitments and Conting98

Other Commitments and Contingencies (Future Minimum Lease Payments Required Under Operating And Capital Leases) (Details) $ in Millions	Dec. 31, 2016USD ($)	[1]
Unrecorded Unconditional Purchase Obligation [Line Items]
2,017	$ 8.7
2,018	7.4
2,019	6.6
2,020	6.3
2,021	5.5
After	23.5
Total future minimum payments	$ 58
[1]	Operating lease expense includes amounts for fleet leases and storage well leases that can be renewed beyond the initial lease term, but the anticipated payments associated with the renewals do not meet the definition of expected minimum lease payments and, therefore, are not included above.

Other Commitments and Conting99

Other Commitments and Contingencies (Estimated Aggregate Amounts Of Minimum Fixed Payments On Purchase And Service Obligations) (Details) $ in Millions	Dec. 31, 2016USD ($)
Pipeline Service Agreements
Other Commitments And Contingencies [Line Items]
2,017	$ 67
2,018	63.4
2,019	55.9
2,020	38.4
2,021	32.2
After	187
Total future minimum payments	443.9
IBM Service Agreement
Other Commitments And Contingencies [Line Items]
2,017	34.3
2,018	31.8
2,019	31.2
2,020	30.9
2,021	0
After	0
Total future minimum payments	$ 128.2

Accumulated Other Comprehens100

Accumulated Other Comprehensive Loss (Narrative) (Details) $ in Millions	Aug. 31, 2010USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2008USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Number Of Notes Tranches Through Private Placement Issuance	2
Millennium Pipeline
Accumulated Other Comprehensive Income (Loss) [Line Items]
Number of interest rate swap agreements				3
Notional amount of interest rate swap agreements				$ 420
Number of counterparties entered into interest rate swap agreement				7
Refinancing of long-term debt	$ 725
Debt Instrument, Maturity Date		Jun. 1, 2025
Other Comprehensive Income Unrecognized Gain Loss On Derivatives Arising During Period Net Of Tax		$ 13.2	$ 14.3
Unrealized loss, amortization period		15 years
Notes Due 2027 | Millennium Pipeline
Accumulated Other Comprehensive Income (Loss) [Line Items]
Refinancing of long-term debt	$ 375
Debt Instrument, Interest Rate, Stated Percentage	5.33%
Debt Instrument, Maturity Date	Jun. 30, 2027
Notes Due 2032 | Millennium Pipeline
Accumulated Other Comprehensive Income (Loss) [Line Items]
Refinancing of long-term debt	$ 350
Debt Instrument, Interest Rate, Stated Percentage	6.00%
Debt Instrument, Maturity Date	Jun. 30, 2032

Accumulated Other Comprehens101

Accumulated Other Comprehensive Loss (Components Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	$ (27)		$ (34.5)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]	3.7		4.1		$ (9.3)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	(0.4)	[2]	1.3	[2]	0.6
Total Comprehensive Income	[1]	3.3		5.4		(8.7)
Ending Balance	[1]	(23.9)		(27)		(34.5)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(14.3)		(16.6)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]	0		(0.9)		0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	1.3	[2]	1.1	[2]	1
Total Comprehensive Income	[1]	1.3		0.2		1
Ending Balance	[1]	(13.2)		(14.3)		(16.6)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]	(12.7)		(17.9)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	[1]	3.7		5		(9.3)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[1]	(1.7)	[2]	0.2	[2]	(0.4)
Total Comprehensive Income	[1]	2		5.2		(9.7)
Ending Balance	[1]	(10.7)		(12.7)		(17.9)
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Comprehensive Income	[1]	0.2		2.1
Accumulated Defined Benefit Plans Adjustment Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Comprehensive Income	[1]	0		0
AOCI Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total Comprehensive Income	[1]	$ 0.2		$ 2.1
Predecessor
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]					(25.8)
Predecessor | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]					(17.6)
Predecessor | Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	[1]					$ (8.2)
[1]	All amounts are net of tax. Amounts in parentheses indicate debits.
[2]	Includes amounts allocated to noncontrolling interest.

Other, Net (Schedule Of Other N

Other, Net (Schedule Of Other Net) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Nonoperating Income (Expense) [Abstract]
AFUDC Equity	$ 34.9	$ 28.3	$ 11
Miscellaneous	0.2	1	(2.2)
Total Other, net	$ 35.1	$ 29.3	$ 8.8

Interest Expense (Narrative) (D

Interest Expense (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Interest Expense [Abstract]
Accelerated amortization of deferred costs	$ 5.7

Interest Expense (Schedule of I

Interest Expense (Schedule of Interest Expense) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014
Interest Expense [Abstract]
Interest on long-term debt		$ 111		$ 67.5	$ 0
Interest on short-term borrowings		0.2		1.4	0
Debt discount/cost amortization		10.2	[1]	3.1	0
Allowance for funds used during construction		(5.1)		(6.8)	0
Other		2.8		2.4	0
Total Interest Expense	[2]	$ 119.1		$ 67.6	$ 0
[1]	Debt discount/cost amortization for 2016 primarily consists of the accelerated amortization of $5.7 million of deferred costs associated with the CPG and CPPL revolving credit facilities. Refer to Note 5, "Short-term Borrowings" for additional information regarding the early termination of the revolving credit facilities.
[2]	Refer to Note 4, "Transactions with Affiliates" for a discussion of interest expense-affiliated for the year ended December 31, 2016, 2015 and 2014.

Segments of Business (Narrative

Segments of Business (Narrative) (Details)	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Number of Reportable Segments	1

Supplemental Cash Flow Infor106

Supplemental Cash Flow Information Supplemental Cash Flow Information (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Supplemental Cash Flow Elements [Abstract]
Cash Paid for Taxes Under Tax Allocation Agreement	$ 20.9

Supplemental Cash Flow Infor107

Supplemental Cash Flow Information (Schedule of Supplemental Cash Flow Information) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Supplemental Cash Flow Information [Abstract]
Capital expenditures included in current liabilities	[1]	$ 146.1	$ 128.4		$ 78.5
Cash paid for interest, net of interest capitalized amounts		111.1	96.9		53.6
Cash paid for income taxes		$ 4.1	$ 32.3	[2]	$ 21.2
[1]	Capital expenditures included in current liabilities is comprised of "Accrued capital expenditures" and certain other amounts included within "Accounts payable" on the Consolidated Balance Sheets.
[2]	Cash paid for income taxes for the year ended December 31, 2015 includes $20.9 million paid to NiSource under the Tax Allocation Agreement.

Concentration of Credit Risk (N

Concentration of Credit Risk (Narrative) (Details)	12 Months Ended
	Dec. 31, 2016
Risks and Uncertainties [Abstract]
Concentration Risk, Benchmark Description	greater than 10% of total operating revenues

Concentration of Credit Risk (S

Concentration of Credit Risk (Schedule of Concentration of Credit Risk) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Concentration Risk [Line Items]
Revenues		$ 1,382	$ 1,334.9	$ 1,348
Credit Concentration Risk
Concentration Risk [Line Items]
Revenues	[1]	$ 169.7	$ 167.3	$ 168.5
Concentration Risk, Percentage	[1]	12.30%	12.50%	12.50%
[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 agreements with third parties which ultimately can decrease the net revenue amount CPG receives from Columbia Gas of Ohio in any given period.

Quarterly Financial Data (Un110

Quarterly Financial Data (Unaudited) (Schedule Of Quarterly Financial Data) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Data [Abstract]
Total Operating Revenues	$ 376.5	$ 327.1	$ 313.9	$ 364.5	$ 357.9	$ 320.9	$ 316.1	$ 340
Operating Income (Loss)	127.4	(53)	91.5	151.7	122.2	135.9	107.3	162.7	$ 317.6	$ 528.1	$ 491.6
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	68.1	(49.6)	48.6	86.6	75.4	74.9	60.1	97.1	153.7	307.5	268.7
Results from Discontinued Operations-net of taxes	0	0	0	0.2	0	(0.1)	(0.3)	0	0.2	(0.4)	(0.6)
Net Income Attributable to CPG	$ 58.2	$ (52.5)	$ 38.9	$ 72.2	$ 63.4	$ 63	$ 50.8	$ 90	$ 116.8	$ 267.2	$ 268.1

Condensed Consolidating Fina111

Condensed Consolidating Financial Statements (Narrative) (Details) $ in Millions	Dec. 31, 2016USD ($)
Senior Notes
Guarantor Obligations [Line Items]
Face amount of notes	$ 2,750

Condensed Consolidating Fina112

Condensed Consolidating Financial Statements (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current Assets
Cash and cash equivalents		$ 79.9	$ 930.9	$ 0.5	$ 0.4
Accounts receivable, net		194.2	152.4
Accounts receivable-affiliated		55.8	0
Materials and supplies, at average cost		26	32.8
Exchange gas receivable		27.7	19
Deferred property taxes		61.2	52
Taxes receivable		0
Prepayments and other		28.9	48.5
Total Current Assets		473.7	1,235.6
Investments
Unconsolidated affiliates		446.7	438.1
Consolidated affiliates		0	0
Other investments		0.8	13.8
Total Investments		447.5	451.9
Property, Plant and Equipment
Property, plant and equipment		10,461.2	9,052.3
Accumulated depreciation and amortization		(3,126.2)	(2,988.6)
Net Property, Plant and Equipment		7,335	6,063.7
Other Noncurrent Assets
Regulatory assets		172.9	177.7
Goodwill		1,975.5	1,975.5
Notes receivable-affiliated		0	0
Postretirement and postemployment benefits assets		121.8	115.7
Deferred income taxes		0	0
Deferred charges and other		11.3	15.5
Total Other Noncurrent Assets		2,281.5	2,284.4
Total Assets		10,537.7	10,035.6
Current Liabilities
Short-term borrowings		0	15
Short-term borrowings-affiliated		0	0
Accounts payable		70.4	56.8
Accounts payable-affiliated		4	0
Customer deposits		17.3	17.9
Taxes accrued		116.9	106
Interest accrued		9.4	9.5
Exchange gas payable		27.2	18.6
Deferred revenue		3.9	15
Accrued capital expenditures		111.4	100.1
Accrued compensation and related costs		62.3	51.9
Other accruals		110.1	70
Total Current Liabilities		532.9	460.8
Noncurrent Liabilities
Long-term debt		2,728.6	2,725.6
Long-term debt-affiliated		0	0
Deferred income taxes		1,500.4	1,348.1
Accrued liability for postretirement and postemployment benefits		32.2	49.4
Regulatory liabilities		273.6	321.6
Asset retirement obligations		20.8	25.7	23.2
Other noncurrent liabilities		59.8	91.4
Total Noncurrent Liabilities		4,615.4	4,561.8
Total Liabilities		5,148.3	5,022.6
Temporary Equity
Redeemable noncontrolling interest		952.9	0
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,150 and 399,841,350 shares outstanding, respectively		0.1	4
Additional paid-in capital		4,513.8	4,032.7
(Accumulated deficit) Retained earnings		(53.5)	46.9
Net Parent Investment		0	0
Accumulated Other Comprehensive Income (Loss), Net of Tax	[1]	(23.9)	(27)	(34.5)
Total CPG Equity		4,436.5	4,056.6	4,176.3
Noncontrolling Interest		0	956.4
Total Equity		4,436.5	5,013
Total Liabilities, Temporary Equity and Equity		10,537.7	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		(1,513.3)	(260)
Materials and supplies, at average cost		0	0
Exchange gas receivable		0	0
Deferred property taxes		0	0
Taxes receivable		(112.2)
Prepayments and other		0	(5.7)
Total Current Assets		(1,625.5)	(265.7)
Investments
Unconsolidated affiliates		0	0
Consolidated affiliates		(18,992.3)	(18,353.3)
Other investments		0	0
Total Investments		(18,992.3)	(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		(0.4)	(0.4)
Deferred income taxes		(84.8)	(18.9)
Deferred charges and other		0	0
Total Other Noncurrent Assets		(1,933.4)	(1,867.5)
Total Assets		(22,551.2)	(20,486.5)
Current Liabilities
Short-term borrowings			0
Short-term borrowings-affiliated		(1,494.4)	(233.3)
Accounts payable		0	0
Accounts payable-affiliated		(18.9)	(26.7)
Customer deposits		0	0
Taxes accrued		(112.2)	(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		(1,625.5)	(265.7)
Noncurrent Liabilities
Long-term debt		0	0
Long-term debt-affiliated		(1,848.2)	(1,848.2)
Deferred income taxes		(84.8)	(18.9)
Accrued liability for postretirement and postemployment benefits		(0.4)	(0.4)
Regulatory liabilities		0	0
Asset retirement obligations		0	0
Other noncurrent liabilities		0	0
Total Noncurrent Liabilities		(1,933.4)	(1,867.5)
Total Liabilities		(3,558.9)	(2,133.2)
Temporary Equity
Redeemable noncontrolling interest		(952.9)
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,150 and 399,841,350 shares outstanding, respectively		0	0
Additional paid-in capital		0	0
(Accumulated deficit) Retained earnings			0
Net Parent Investment		(18,113)	(17,479)
Accumulated Other Comprehensive Income (Loss), Net of Tax		73.6	82.1
Total CPG Equity		(18,039.4)	(17,396.9)
Noncontrolling Interest			(956.4)
Total Equity			(18,353.3)
Total Liabilities, Temporary Equity and Equity		(22,551.2)	(20,486.5)
Columbia Pipeline Group
Current Assets
Cash and cash equivalents		38.8	800	0	0
Accounts receivable, net		0	0
Accounts receivable-affiliated		799.6	14.6
Materials and supplies, at average cost		0	0
Exchange gas receivable		0	0
Deferred property taxes		0	0
Taxes receivable		68.6
Prepayments and other		0.3	0.3
Total Current Assets		907.3	814.9
Investments
Unconsolidated affiliates		0	0
Consolidated affiliates		5,421.1	5,174.6
Other investments		0	12
Total Investments		5,421.1	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		1.7	4.9
Total Other Noncurrent Assets		1,849.9	1,872
Total Assets		8,178.3	7,873.5
Current Liabilities
Short-term borrowings			0
Short-term borrowings-affiliated		0	99
Accounts payable		0	0.1
Accounts payable-affiliated		7	10.8
Customer deposits		0	0
Taxes accrued		0	0
Interest accrued		9.3	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		0.1	0
Total Current Liabilities		16.4	119.3
Noncurrent Liabilities
Long-term debt		2,728.6	2,725.6
Long-term debt-affiliated		0	0
Deferred income taxes		42.8	0
Accrued liability for postretirement and postemployment benefits		0.7	0.3
Regulatory liabilities		0	0
Asset retirement obligations		0	0
Other noncurrent liabilities		0.4	15.3
Total Noncurrent Liabilities		2,772.5	2,741.2
Total Liabilities		2,788.9	2,860.5
Temporary Equity
Redeemable noncontrolling interest		952.9
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,150 and 399,841,350 shares outstanding, respectively		0.1	4
Additional paid-in capital		4,513.8	4,032.7
(Accumulated deficit) Retained earnings		(53.5)	46.9
Net Parent Investment		0	0
Accumulated Other Comprehensive Income (Loss), Net of Tax		(23.9)	(27)
Total CPG Equity		4,436.5	4,056.6
Noncontrolling Interest			956.4
Total Equity			5,013
Total Liabilities, Temporary Equity and Equity		8,178.3	7,873.5
Columbia Energy Group
Current Assets
Cash and cash equivalents		30	46.7	0	0
Accounts receivable, net		0.1	5.6
Accounts receivable-affiliated		579.5	85.6
Materials and supplies, at average cost		0	0
Exchange gas receivable		0	0
Deferred property taxes		0	0
Taxes receivable		43.6
Prepayments and other		0.4	10.1
Total Current Assets		653.6	148
Investments
Unconsolidated affiliates		0	0
Consolidated affiliates		7,482	7,569.8
Other investments		0	0.3
Total Investments		7,482	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		56.5	35.1
Goodwill		0	0
Notes receivable-affiliated		0	0
Postretirement and postemployment benefits assets		0.8	0.5
Deferred income taxes		0	0
Deferred charges and other		0	0
Total Other Noncurrent Assets		57.3	35.6
Total Assets		8,192.9	7,753.7
Current Liabilities
Short-term borrowings			0
Short-term borrowings-affiliated		0	0
Accounts payable		0.6	0
Accounts payable-affiliated		5.1	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		0.5	0.3
Total Current Liabilities		6.2	5.1
Noncurrent Liabilities
Long-term debt		0	0
Long-term debt-affiliated		1,217.3	1,217.3
Deferred income taxes		1,542.4	1,350.4
Accrued liability for postretirement and postemployment benefits		6.4	8.3
Regulatory liabilities		10.2	10.5
Asset retirement obligations		0	0
Other noncurrent liabilities		1.8	0.2
Total Noncurrent Liabilities		2,778.1	2,586.7
Total Liabilities		2,784.3	2,591.8
Temporary Equity
Redeemable noncontrolling interest		952.9
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,150 and 399,841,350 shares outstanding, respectively		0	0
Additional paid-in capital		0	0
(Accumulated deficit) Retained earnings		0	0
Net Parent Investment		4,479.3	4,232.3
Accumulated Other Comprehensive Income (Loss), Net of Tax		(23.6)	(26.8)
Total CPG Equity		4,455.7	4,205.5
Noncontrolling Interest			956.4
Total Equity			5,161.9
Total Liabilities, Temporary Equity and Equity		8,192.9	7,753.7
Columbia OpCo
Current Assets
Cash and cash equivalents		0	1.9	0	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
Taxes receivable		0
Prepayments and other		0	0
Total Current Assets		0	5.3
Investments
Unconsolidated affiliates		0	0
Consolidated affiliates		6,089.2	5,608.9
Other investments		0	0
Total Investments		6,089.2	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		8,064.7	7,589.7
Current Liabilities
Short-term borrowings			0
Short-term borrowings-affiliated		570.8	0
Accounts payable		0	0
Accounts payable-affiliated		0.8	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		571.6	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		571.6	0
Temporary Equity
Redeemable noncontrolling interest		0
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,150 and 399,841,350 shares outstanding, respectively		0	0
Additional paid-in capital		0	0
(Accumulated deficit) Retained earnings		0	0
Net Parent Investment		7,516.2	7,615.4
Accumulated Other Comprehensive Income (Loss), Net of Tax		(23.1)	(25.7)
Total CPG Equity		7,493.1	7,589.7
Noncontrolling Interest			0
Total Equity			7,589.7
Total Liabilities, Temporary Equity and Equity		8,064.7	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
Taxes receivable		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
Temporary Equity
Redeemable noncontrolling interest		0
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,150 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 Income (Loss), Net of Tax		0	0
Total CPG Equity		0	0
Noncontrolling Interest			0
Total Equity			0
Total Liabilities, Temporary Equity and Equity		0	0
Non-Guarantor Subsidiaries
Current Assets
Cash and cash equivalents		11.1	82.3	$ 0.5	$ 0.4
Accounts receivable, net		194.1	146.8
Accounts receivable-affiliated		190	156.4
Materials and supplies, at average cost		26	32.8
Exchange gas receivable		27.7	19
Deferred property taxes		61.2	52
Taxes receivable		0
Prepayments and other		28.2	43.8
Total Current Assets		538.3	533.1
Investments
Unconsolidated affiliates		446.7	438.1
Consolidated affiliates		0	0
Other investments		0.8	1.5
Total Investments		447.5	439.6
Property, Plant and Equipment
Property, plant and equipment		10,461.2	9,052.3
Accumulated depreciation and amortization		(3,126.2)	(2,988.6)
Net Property, Plant and Equipment		7,335	6,063.7
Other Noncurrent Assets
Regulatory assets		116.4	142.6
Goodwill		0	0
Notes receivable-affiliated		0	0
Postretirement and postemployment benefits assets		121.4	115.6
Deferred income taxes		84.8	0
Deferred charges and other		9.6	10.6
Total Other Noncurrent Assets		332.2	268.8
Total Assets		8,653	7,305.2
Current Liabilities
Short-term borrowings			15
Short-term borrowings-affiliated		923.6	134.3
Accounts payable		69.8	56.7
Accounts payable-affiliated		10	11.1
Customer deposits		17.3	17.9
Taxes accrued		229.1	111.7
Interest accrued		0.1	0.1
Exchange gas payable		27.2	18.6
Deferred revenue		3.9	15
Accrued capital expenditures		111.4	100.1
Accrued compensation and related costs		62.3	51.9
Other accruals		109.5	69.7
Total Current Liabilities		1,564.2	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		25.5	41.2
Regulatory liabilities		263.4	311.1
Asset retirement obligations		20.8	25.7
Other noncurrent liabilities		57.6	75.9
Total Noncurrent Liabilities		998.2	1,101.4
Total Liabilities		2,562.4	1,703.5
Temporary Equity
Redeemable noncontrolling interest		0
Equity
Common stock, $0.01 par value, 10,001,000 and 2,000,000,000 shares authorized, respectively; 10,000,150 and 399,841,350 shares outstanding, respectively		0	0
Additional paid-in capital		0	0
(Accumulated deficit) Retained earnings			0
Net Parent Investment		6,117.5	5,631.3
Accumulated Other Comprehensive Income (Loss), Net of Tax		(26.9)	(29.6)
Total CPG Equity		6,090.6	5,601.7
Noncontrolling Interest			0
Total Equity			5,601.7
Total Liabilities, Temporary Equity and Equity		$ 8,653	$ 7,305.2
[1]	All amounts are net of tax. Amounts in parentheses indicate debits.

Condensed Consolidating Fina113

Condensed Consolidating Financial Statements (Condensed Consolidating Statements of Operations) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Revenues
Transportation revenues										$ 1,155.1	$ 1,054.4	$ 990.8
Transportation revenues-affiliated										0	47.5	95.7
Storage revenues										196.5	171.4	144
Storage revenues-affiliated										0	26.2	53.2
Other revenues										30.4	35.4	64.3
Total Operating Revenues										1,382	1,334.9	1,348
Operating Expenses
Operation and maintenance										863.2	652.1	628.4
Operation and maintenance-affiliated										0	52.9	123.2
Depreciation and amortization										172.8	139.9	118.8
Gain on sale of assets										(16.6)	(55.3)	(34.5)
Impairment of long-lived assets										26.1	2.4	0
Property and other taxes										83.2	75.3	67.1
Total Operating Expenses										1,128.7	867.3	903
Equity Earnings in Unconsolidated Affiliates										64.3	60.5	46.6
Equity Earnings in Consolidated Affiliates										0	0	0
Operating Income		$ 127.4	$ (53)	$ 91.5	$ 151.7	$ 122.2	$ 135.9	$ 107.3	$ 162.7	317.6	528.1	491.6
Other Income (Deductions)
Interest expense	[1]									(119.1)	(67.6)	0
Interest expense-affiliated										(2.1)	(29.3)	(62)
Other, net										35.1	29.3	8.8
Total Other Deductions, net										(86.1)	(67.6)	(53.2)
Income from Continuing Operations before Income Taxes										231.5	460.5	438.4
Income Taxes										77.8	153	169.7
Income from Continuing Operations		68.1	(49.6)	48.6	86.6	75.4	74.9	60.1	97.1	153.7	307.5	268.7
Income (Loss) from Discontinued Operations-net of taxes		0	0	0	0.2	0	(0.1)	(0.3)	0	0.2	(0.4)	(0.6)
Net Income										153.9	307.1	268.1
Less: Net income attributable to noncontrolling interest										37.1	39.9
Net Income Attributable to CPG		$ 58.2	$ (52.5)	$ 38.9	$ 72.2	$ 63.4	$ 63	$ 50.8	$ 90	116.8	267.2	268.1
Consolidating adjustments and eliminations
Operating Revenues
Transportation revenues										0	0	0
Transportation revenues-affiliated											0	0
Storage revenues										0	0	0
Storage revenues-affiliated											0	0
Other revenues										0	0	0
Total Operating Revenues										0	0	0
Operating Expenses
Operation and maintenance										(0.2)	0	0
Operation and maintenance-affiliated										(3.7)	(2.2)	0
Depreciation and amortization										0	0	0
Gain on sale of assets										0	0	0
Impairment of long-lived assets										0	0
Property and other taxes										0	0	0
Total Operating Expenses										(3.9)	(2.2)	0
Equity Earnings in Unconsolidated Affiliates										0	0	0
Equity Earnings in Consolidated Affiliates										(1,227.1)	(1,400.2)	(538.3)
Operating Income										(1,223.2)	(1,398)	(538.3)
Other Income (Deductions)
Interest expense										5.1	6.9
Interest expense-affiliated										80.3	40.8	0
Other, net										(85.4)	(47.7)	0
Total Other Deductions, net										0	0	0
Income from Continuing Operations before Income Taxes										(1,223.2)	(1,398)	(538.3)
Income Taxes										0	0	0
Income from Continuing Operations										(1,223.2)	(1,398)	(538.3)
Income (Loss) from Discontinued Operations-net of taxes										(0.2)	0.4	0.6
Net Income										(1,223.4)	(1,397.6)	(537.7)
Less: Net income attributable to noncontrolling interest										(37.1)	(39.9)
Net Income Attributable to CPG										(1,186.3)	(1,357.7)
Columbia Pipeline Group
Operating Revenues
Transportation revenues										0	0	0
Transportation revenues-affiliated											0	0
Storage revenues										0	0	0
Storage revenues-affiliated											0	0
Other revenues										0	0	0
Total Operating Revenues										0	0	0
Operating Expenses
Operation and maintenance										146.6	20.5	0
Operation and maintenance-affiliated										3.7	2.2	0
Depreciation and amortization										0	0	0
Gain on sale of assets										0	0	0
Impairment of long-lived assets										0	0
Property and other taxes										0.1	0	0
Total Operating Expenses										150.4	22.7	0
Equity Earnings in Unconsolidated Affiliates										0	0	0
Equity Earnings in Consolidated Affiliates										284	341.2	268.7
Operating Income										133.6	318.5	268.7
Other Income (Deductions)
Interest expense										(121)	(73)
Interest expense-affiliated										(2.1)	(2.5)	0
Other, net										81.1	45.4	0
Total Other Deductions, net										(42)	(30.1)	0
Income from Continuing Operations before Income Taxes										91.6	288.4	268.7
Income Taxes										(62.1)	(19.1)	0
Income from Continuing Operations										153.7	307.5	268.7
Income (Loss) from Discontinued Operations-net of taxes										0.2	(0.4)	(0.6)
Net Income										153.9	307.1	268.1
Less: Net income attributable to noncontrolling interest										37.1	39.9
Net Income Attributable to CPG										116.8	267.2
Columbia Energy Group
Operating Revenues
Transportation revenues										0	0	0
Transportation revenues-affiliated											0	0
Storage revenues										0	0	0
Storage revenues-affiliated											0	0
Other revenues										0	0	0
Total Operating Revenues										0	0	0
Operating Expenses
Operation and maintenance										0.8	(1.2)	(2.6)
Operation and maintenance-affiliated										0	0.4	0.5
Depreciation and amortization										0.7	0	0
Gain on sale of assets										0	0	0
Impairment of long-lived assets										0	1.8
Property and other taxes										1.4	0	0
Total Operating Expenses										2.9	1	(2.1)
Equity Earnings in Unconsolidated Affiliates										0	0	0
Equity Earnings in Consolidated Affiliates										465.2	529.4	269.6
Operating Income										462.3	528.4	271.7
Other Income (Deductions)
Interest expense										0	0
Interest expense-affiliated										(45)	(40.8)	0
Other, net										4.6	0.5	(0.1)
Total Other Deductions, net										(40.4)	(40.3)	(0.1)
Income from Continuing Operations before Income Taxes										421.9	488.1	271.6
Income Taxes										137.8	146.6	2.9
Income from Continuing Operations										284.1	341.5	268.7
Income (Loss) from Discontinued Operations-net of taxes										0.2	(0.4)	(0.6)
Net Income										284.3	341.1	268.1
Less: Net income attributable to noncontrolling interest										37.1	39.9
Net Income Attributable to CPG										247.2	301.2
Columbia OpCo
Operating Revenues
Transportation revenues										0	0	0
Transportation revenues-affiliated											0	0
Storage revenues										0	0	0
Storage revenues-affiliated											0	0
Other revenues										0	0	0
Total Operating Revenues										0	0	0
Operating Expenses
Operation and maintenance										0	0	0
Operation and maintenance-affiliated										0	0	0
Depreciation and amortization										0	0	0
Gain on sale of assets										0	0	0
Impairment of long-lived assets										0	0
Property and other taxes										0.1	0	0
Total Operating Expenses										0.1	0	0
Equity Earnings in Unconsolidated Affiliates										0	0	0
Equity Earnings in Consolidated Affiliates										477.9	529.6	0
Operating Income										477.8	529.6	0
Other Income (Deductions)
Interest expense										0	0
Interest expense-affiliated										(3.7)	0	0
Other, net										0	3.5	0
Total Other Deductions, net										(3.7)	3.5	0
Income from Continuing Operations before Income Taxes										474.1	533.1	0
Income Taxes										0	0	0
Income from Continuing Operations										474.1	533.1	0
Income (Loss) from Discontinued Operations-net of taxes										0	0	0
Net Income										474.1	533.1	0
Less: Net income attributable to noncontrolling interest										0	0
Net Income Attributable to CPG										474.1	533.1
CPG OpCo GP
Operating Revenues
Transportation revenues										0	0	0
Transportation revenues-affiliated											0	0
Storage revenues										0	0	0
Storage revenues-affiliated											0	0
Other revenues										0	0	0
Total Operating Revenues										0	0	0
Operating Expenses
Operation and maintenance										0	0	0
Operation and maintenance-affiliated										0	0	0
Depreciation and amortization										0	0	0
Gain on sale of assets										0	0	0
Impairment of long-lived assets										0	0
Property and other taxes										0	0	0
Total Operating Expenses										0	0	0
Equity Earnings in Unconsolidated Affiliates										0	0	0
Equity Earnings in Consolidated Affiliates										0	0	0
Operating Income										0	0	0
Other Income (Deductions)
Interest expense										0	0
Interest expense-affiliated										0	0	0
Other, net										0	0	0
Total Other Deductions, net										0	0	0
Income from Continuing Operations before Income Taxes										0	0	0
Income Taxes										0	0	0
Income from Continuing Operations										0	0	0
Income (Loss) from Discontinued Operations-net of taxes										0	0	0
Net Income										0	0	0
Less: Net income attributable to noncontrolling interest										0	0
Net Income Attributable to CPG										0	0
Non-Guarantor Subsidiaries
Operating Revenues
Transportation revenues										1,155.1	1,054.4	990.8
Transportation revenues-affiliated											47.5	95.7
Storage revenues										196.5	171.4	144
Storage revenues-affiliated											26.2	53.2
Other revenues										30.4	35.4	64.3
Total Operating Revenues										1,382	1,334.9	1,348
Operating Expenses
Operation and maintenance										716	632.8	631
Operation and maintenance-affiliated										0	52.5	122.7
Depreciation and amortization										172.1	139.9	118.8
Gain on sale of assets										(16.6)	(55.3)	(34.5)
Impairment of long-lived assets										26.1	0.6
Property and other taxes										81.6	75.3	67.1
Total Operating Expenses										979.2	845.8	905.1
Equity Earnings in Unconsolidated Affiliates										64.3	60.5	46.6
Equity Earnings in Consolidated Affiliates										0	0	0
Operating Income										467.1	549.6	489.5
Other Income (Deductions)
Interest expense										(3.2)	(1.5)
Interest expense-affiliated										(31.6)	(26.8)	(62)
Other, net										34.8	27.6	8.9
Total Other Deductions, net										0	(0.7)	(53.1)
Income from Continuing Operations before Income Taxes										467.1	548.9	436.4
Income Taxes										2.1	25.5	166.8
Income from Continuing Operations										465	523.4	269.6
Income (Loss) from Discontinued Operations-net of taxes										0	0	0
Net Income										465	523.4	$ 269.6
Less: Net income attributable to noncontrolling interest										0	0
Net Income Attributable to CPG										$ 465	$ 523.4
[1]	Refer to Note 4, "Transactions with Affiliates" for a discussion of interest expense-affiliated for the year ended December 31, 2016, 2015 and 2014.

Condensed Consolidating Fina114

Condensed Consolidating Financial Statements (Condensed Consolidating Statements of Comprehensive Income) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Condensed Statement of Income Captions [Line Items]
Net Income		$ 153.9		$ 307.1		$ 268.1
Net unrealized gain on cash flow hedges	[1]	1.3		0.2		1
Unrecognized pension and OPEB benefit (cost)	[2]	2	[3]	5.2	[3]	(9.7)
Total other comprehensive income (loss)	[4]	3.3		5.4		(8.7)
Total Comprehensive Income		157.2		312.5		259.4
Less: Comprehensive Income-noncontrolling interest		37.3		40		0
Comprehensive Income-controlling interests		119.9		272.5		259.4
Consolidating adjustments and eliminations
Condensed Statement of Income Captions [Line Items]
Net Income		(1,223.4)		(1,397.6)		(537.7)
Net unrealized gain on cash flow hedges		(1.3)		(0.2)		(1)
Unrecognized pension and OPEB benefit (cost)		(2)		(5.2)		9.7
Total other comprehensive income (loss)		(3.3)		(5.4)		8.7
Total Comprehensive Income		(1,226.7)		(1,403)		(529)
Less: Comprehensive Income-noncontrolling interest		(37.3)		(40)
Comprehensive Income-controlling interests		(1,189.4)		(1,363)
Columbia Pipeline Group
Condensed Statement of Income Captions [Line Items]
Net Income		153.9		307.1		268.1
Net unrealized gain on cash flow hedges		1.3		0.2		1
Unrecognized pension and OPEB benefit (cost)		2		5.2		(9.7)
Total other comprehensive income (loss)		3.3		5.4		(8.7)
Total Comprehensive Income		157.2		312.5		259.4
Less: Comprehensive Income-noncontrolling interest		37.3		40
Comprehensive Income-controlling interests		119.9		272.5
Columbia Energy Group
Condensed Statement of Income Captions [Line Items]
Net Income		284.3		341.1		268.1
Net unrealized gain on cash flow hedges		(0.8)		(1.6)		0
Unrecognized pension and OPEB benefit (cost)		1.7		5.4		(9.7)
Total other comprehensive income (loss)		0.9		3.8		(9.7)
Total Comprehensive Income		285.2		344.9		258.4
Less: Comprehensive Income-noncontrolling interest		37.3		40
Comprehensive Income-controlling interests		247.9		304.9
Columbia OpCo
Condensed Statement of Income Captions [Line Items]
Net Income		474.1		533.1		0
Net unrealized gain on cash flow hedges		0		0		0
Unrecognized pension and OPEB benefit (cost)		0		0		0
Total other comprehensive income (loss)		0		0		0
Total Comprehensive Income		474.1		533.1		0
Less: Comprehensive Income-noncontrolling interest		0		0
Comprehensive Income-controlling interests		474.1		533.1
CPG OpCo GP
Condensed Statement of Income Captions [Line Items]
Net Income		0		0		0
Net unrealized gain on cash flow hedges		0		0		0
Unrecognized pension and OPEB benefit (cost)		0		0		0
Total other comprehensive income (loss)		0		0		0
Total Comprehensive Income		0		0		0
Less: Comprehensive Income-noncontrolling interest		0		0
Comprehensive Income-controlling interests		0		0
Non-Guarantor Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net Income		465		523.4		269.6
Net unrealized gain on cash flow hedges		2.1		1.8		1
Unrecognized pension and OPEB benefit (cost)		0.3		(0.2)		0
Total other comprehensive income (loss)		2.4		1.6		1
Total Comprehensive Income		467.4		525		$ 270.6
Less: Comprehensive Income-noncontrolling interest		0		0
Comprehensive Income-controlling interests		$ 467.4		$ 525
[1]	Net unrealized gain on derivatives qualifying as cash flow hedges, net of $0.7 million, $0.2 million and $0.7 million tax expense in 2016, 2015 and 2014, respectively.
[2]	Unrecognized pension and OPEB benefit (cost), net of $1.3 million tax expense, $1.2 million tax benefit, and $6.1 million tax benefit in 2016, 2015 and 2014, respectively.
[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 Fina115

Condensed Consolidating Financial Statements (Condensed Consolidating Statements of of Cash Flows) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Activities
Net Cash Provided by (Used in) Operating Activities	$ 360.2	$ 493.5	$ 564.8
Investing Activities
Capital expenditures	(1,438.1)	(1,181)	(747.2)
Insurance recoveries	3	2.1	11.3
Changes in short-term lendings-affiliated	0	145.5	(57.2)
Proceeds from disposition of assets	10.4	77.6	9.3
Contributions to equity investees	(6.2)	(1.4)	(69.2)
Distributions from equity investees	2.2	16	0
Other investing activities	0.6	(27.4)	(7.1)
Net Cash Flows used for Investing Activities	(1,428.1)	(968.6)	(860.1)
Financing Activities
Change in short-term borrowings	(15)	15	0
Change in short-term borrowings-affiliated	500	(252.5)	(467.1)
Repayment of short-term debt to related parties	(500)	0	0
Issuance of long-term debt	0	2,745.9	0
Payment of capital lease obligations and other debt related costs	(5.4)	(23.6)	(6.4)
Issuance of long-term debt-affiliated	0	1,217.3	768.9
Payments of long-term debt-affiliated, including current portion	0	(2,807.8)	0
Proceeds from issuance of common units, net of offering costs	0	1,168.4	0
Issuance of common stock, net of offering costs	0	1,394.7	0
Contribution of capital from parent	500.1	0
Distribution of IPO proceeds to NiSource	0	(500)	0
Distribution to NiSource	0	(1,450)	0
Payments of Distributions to Unitholders	0	0
Distribution to noncontrolling interest	(41)	(23.2)	0
Distribution to noncontrolling interest in Columbia OpCo	0	0
Acquisition of treasury stock	(6.2)	0	0
Dividends paid - common stock	(105.1)	(79.5)	0
Dividends paid to TransCanada	(110.5)	0	0
Distribution received from Columbia OpCo		0
Transfer from NiSource	0	0.8	0
Net Cash Flows from Financing Activities	216.9	1,405.5	295.4
Change in cash and cash equivalents	(851)	930.4	0.1
Cash and cash equivalents at beginning of period	930.9	0.5	0.4
Cash and cash equivalents at end of period	79.9	930.9	0.5
Consolidating adjustments and eliminations
Operating Activities
Net Cash Provided by (Used in) Operating Activities	(608.9)	(20.2)	(2.2)
Investing Activities
Capital expenditures	0	32.7	0
Insurance recoveries	0	0	0
Changes in short-term lendings-affiliated	1,261.1	233.3	0
Proceeds from disposition of assets	0	(32.7)	0
Contributions to equity investees	0	1,663.5	0
Distributions from equity investees	0	0
Other investing activities	0	0	0
Net Cash Flows used for Investing Activities	1,261.1	1,896.8	0
Financing Activities
Change in short-term borrowings	0	0
Change in short-term borrowings-affiliated	(1,261.1)	(233.3)	0
Repayment of short-term debt to related parties	0
Issuance of long-term debt		0
Payment of capital lease obligations and other debt related costs	0	0	0
Issuance of long-term debt-affiliated		0	0
Payments of long-term debt-affiliated, including current portion		0
Proceeds from issuance of common units, net of offering costs		0
Issuance of common stock, 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	2.2
Payments of Distributions to Unitholders	76.9	43.4
Distribution to noncontrolling interest	(41)	(23.2)
Distribution to noncontrolling interest in Columbia OpCo	573	187.3
Acquisition of treasury stock	0
Dividends paid - common stock	0	0
Dividends paid to TransCanada	0
Distribution received from Columbia OpCo		(187.3)
Transfer from NiSource		0
Net Cash Flows from Financing Activities	(652.2)	(1,876.6)	2.2
Change in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	0	0	0
Cash and cash equivalents at end of period	0	0	0
Columbia Pipeline Group
Operating Activities
Net Cash Provided by (Used in) Operating Activities	(213.6)	(29.7)	0
Investing Activities
Capital expenditures	0	0	0
Insurance recoveries	0	0	0
Changes in short-term lendings-affiliated	(736.1)	0	0
Proceeds from disposition of assets	0	0	0
Contributions to equity investees	0	0	0
Distributions from equity investees	0	0
Other investing activities	10.3	(5.2)	0
Net Cash Flows used for Investing Activities	(725.8)	(5.2)	0
Financing Activities
Change in short-term borrowings	0	0
Change in short-term borrowings-affiliated	401	99	0
Repayment of short-term debt to related parties	(500)
Issuance of long-term debt		2,745.9
Payment of capital lease obligations and other debt related costs	(1.1)	(27.9)	0
Issuance of long-term debt-affiliated		0	0
Payments of long-term debt-affiliated, including current portion		(1,848.2)
Proceeds from issuance of common units, net of offering costs		0
Issuance of common stock, net of offering costs		1,394.7
Contribution of capital from parent	500.1	0
Distribution of IPO proceeds to NiSource		0
Distribution to NiSource		(1,450)	0
Payments of Distributions to Unitholders	0	0
Distribution to noncontrolling interest	0	0
Distribution to noncontrolling interest in Columbia OpCo	0	0
Acquisition of treasury stock	(6.2)
Dividends paid - common stock	(105.1)	(79.5)
Dividends paid to TransCanada	(110.5)
Distribution received from Columbia OpCo		0
Transfer from NiSource		0.9
Net Cash Flows from Financing Activities	178.2	834.9	0
Change in cash and cash equivalents	(761.2)	800	0
Cash and cash equivalents at beginning of period	800	0	0
Cash and cash equivalents at end of period	38.8	800	0
Columbia Energy Group
Operating Activities
Net Cash Provided by (Used in) Operating Activities	473.7	(49.6)	(3.7)
Investing Activities
Capital expenditures	0	(32.7)	0
Insurance recoveries	0	0	0
Changes in short-term lendings-affiliated	(490.4)	(83.9)	4.8
Proceeds from disposition of assets	0	26.2	0
Contributions to equity investees	0	(1,217.3)	0
Distributions from equity investees	0	0
Other investing activities	0	0	0
Net Cash Flows used for Investing Activities	(490.4)	(1,307.7)	4.8
Financing Activities
Change in short-term borrowings	0	0
Change in short-term borrowings-affiliated	0	(5.1)	5.2
Repayment of short-term debt to related parties	0
Issuance of long-term debt		0
Payment of capital lease obligations and other debt related costs	0	6.3	(6.3)
Issuance of long-term debt-affiliated		1,217.3	0
Payments of long-term debt-affiliated, including current portion		0
Proceeds from issuance of common units, net of offering costs		0
Issuance of common stock, net of offering costs		0
Contribution of capital from parent	0	0
Distribution of IPO proceeds to NiSource		0
Distribution to NiSource		0	0
Payments of Distributions to Unitholders	0	0
Distribution to noncontrolling interest	0	0
Distribution to noncontrolling interest in Columbia OpCo	0	0
Acquisition of treasury stock	0
Dividends paid - common stock	0	0
Dividends paid to TransCanada	0
Distribution received from Columbia OpCo		187.3
Transfer from NiSource		(1.8)
Net Cash Flows from Financing Activities	0	1,404	(1.1)
Change in cash and cash equivalents	(16.7)	46.7	0
Cash and cash equivalents at beginning of period	46.7	0	0
Cash and cash equivalents at end of period	30	46.7	0
Columbia OpCo
Operating Activities
Net Cash Provided by (Used in) Operating Activities	(3)	3.5	0
Investing Activities
Capital expenditures	0	0	0
Insurance recoveries	0	0	0
Changes in short-term lendings-affiliated	3.3	(3.3)	0
Proceeds from disposition of assets	0	0	0
Contributions to equity investees	0	(446.2)	0
Distributions from equity investees	0	0
Other investing activities	0	0	0
Net Cash Flows used for Investing Activities	3.3	(449.5)	0
Financing Activities
Change in short-term borrowings	0	0
Change in short-term borrowings-affiliated	570.8	0	0
Repayment of short-term debt to related parties	0
Issuance of long-term debt		0
Payment of capital lease obligations and other debt related costs	0	0	0
Issuance of long-term debt-affiliated		0	0
Payments of long-term debt-affiliated, including current portion		0
Proceeds from issuance of common units, net of offering costs		1,170
Issuance of common stock, net of offering costs		0
Contribution of capital from parent	0	0
Distribution of IPO proceeds to NiSource		(500)
Distribution to NiSource		0	0
Payments of Distributions to Unitholders	0	0
Distribution to noncontrolling interest	0	0
Distribution to noncontrolling interest in Columbia OpCo	(573)	(187.3)
Acquisition of treasury stock	0
Dividends paid - common stock	0	0
Dividends paid to TransCanada	0
Distribution received from Columbia OpCo		0
Transfer from NiSource		(34.8)
Net Cash Flows from Financing Activities	(2.2)	447.9	0
Change in cash and cash equivalents	(1.9)	1.9	0
Cash and cash equivalents at beginning of period	1.9	0	0
Cash and cash equivalents at end of period	0	1.9	0
CPG OpCo GP
Operating Activities
Net Cash Provided by (Used in) Operating Activities	0	0	0
Investing Activities
Capital expenditures	0	0	0
Insurance recoveries	0	0	0
Changes in short-term lendings-affiliated	0	0	0
Proceeds from disposition of assets	0	0	0
Contributions to equity investees	0	0	0
Distributions from equity investees	0	0
Other investing activities	0	0	0
Net Cash Flows used for Investing Activities	0	0	0
Financing Activities
Change in short-term borrowings	0	0
Change in short-term borrowings-affiliated	0	0	0
Repayment of short-term debt to related parties	0
Issuance of long-term debt		0
Payment of capital lease obligations and other debt related costs	0	0	0
Issuance of long-term debt-affiliated		0	0
Payments of long-term debt-affiliated, including current portion		0
Proceeds from issuance of common units, net of offering costs		0
Issuance of common stock, net of offering costs		0
Contribution of capital from parent	0	0
Distribution of IPO proceeds to NiSource		0
Distribution to NiSource		0	0
Payments of Distributions to Unitholders	0	0
Distribution to noncontrolling interest	0	0
Distribution to noncontrolling interest in Columbia OpCo	0	0
Acquisition of treasury stock	0
Dividends paid - common stock	0	0
Dividends paid to TransCanada	0
Distribution received from Columbia OpCo		0
Transfer from NiSource		0
Net Cash Flows from Financing Activities	0	0	0
Change in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	0	0	0
Cash and cash equivalents at end of period	0	0	0
Non-Guarantor Subsidiaries
Operating Activities
Net Cash Provided by (Used in) Operating Activities	712	589.5	570.7
Investing Activities
Capital expenditures	(1,438.1)	(1,181)	(747.2)
Insurance recoveries	3	2.1	11.3
Changes in short-term lendings-affiliated	(37.9)	(0.6)	(62)
Proceeds from disposition of assets	10.4	84.1	9.3
Contributions to equity investees	(6.2)	(1.4)	(69.2)
Distributions from equity investees	2.2	16
Other investing activities	(9.7)	(22.2)	(7.1)
Net Cash Flows used for Investing Activities	(1,476.3)	(1,103)	(864.9)
Financing Activities
Change in short-term borrowings	(15)	15
Change in short-term borrowings-affiliated	789.3	(113.1)	(472.3)
Repayment of short-term debt to related parties	0
Issuance of long-term debt		0
Payment of capital lease obligations and other debt related costs	(4.3)	(2)	(0.1)
Issuance of long-term debt-affiliated		0	768.9
Payments of long-term debt-affiliated, including current portion		(959.6)
Proceeds from issuance of common units, net of offering costs		(1.6)
Issuance of common stock, 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	(2.2)
Payments of Distributions to Unitholders	(76.9)	(43.4)
Distribution to noncontrolling interest	0	0
Distribution to noncontrolling interest in Columbia OpCo	0	0
Acquisition of treasury stock	0
Dividends paid - common stock	0	0
Dividends paid to TransCanada	0
Distribution received from Columbia OpCo		0
Transfer from NiSource		36.5
Net Cash Flows from Financing Activities	693.1	595.3	294.3
Change in cash and cash equivalents	(71.2)	81.8	0.1
Cash and cash equivalents at beginning of period	82.3	0.5	0.4
Cash and cash equivalents at end of period	$ 11.1	$ 82.3	$ 0.5