NiSource (NI) 10-Q 3 Nov 15 2015 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Oct. 27, 2015
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Entity Registrant Name	NISOURCE INC/DE
Entity Central Index Key	1,111,711
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		318,671,280

Statements Of Consolidated Inco

Statements Of Consolidated Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net Revenues
Gas Distribution	$ 208.9	$ 240.3	$ 1,595.5	$ 1,878.8
Gas Transportation and Storage	172.1	170.5	739.9	710.5
Electric	428.4	424.6	1,198.7	1,279.4
Other	7.8	2.8	19.9	10.4
Gross Revenues	817.2	838.2	3,554	3,879.1
Cost of Sales (excluding depreciation and amortization)	209.1	262.4	1,307.3	1,769.6
Total Net Revenues	608.1	575.8	2,246.7	2,109.5
Operating Expenses
Operation and maintenance	311.1	327.4	1,076.9	990.5
Depreciation and amortization	132.5	123.8	391	363.1
Loss on sale of assets	1.1	0.1	1.2	1.5
Other taxes	53.7	53.4	197.2	192.2
Total Operating Expenses	498.4	504.7	1,666.3	1,547.3
Operating Income	109.7	71.1	580.4	562.2
Other Income (Deductions)
Interest expense, net	(94.9)	(94.7)	(285.9)	(287.4)
Other, net	5.8	5.7	11.6	13.4
Gains (Losses) on Extinguishment of Debt	0	0	(97.2)	0
Total Other Deductions	(89.1)	(89)	(371.5)	(274)
Income from Continuing Operations before Income Taxes	20.6	(17.9)	208.9	288.2
Income Taxes	5.8	(0.7)	74.7	111.5
Income (Loss) from Continuing Operations	14.8	(17.2)	134.2	176.7
(Loss) Income from Discontinued Operations - net of taxes	(19.7)	48.6	108.5	199.1
Net (Loss) Income	(4.9)	31.4	242.7	375.8
Less: Net income attributable to noncontrolling interest	0	0	15.6	0
Net Income	(4.9)	31.4	227.1	375.8
Income from Continuing Operations	14.8	(17.2)	134.2	176.7
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	$ (19.7)	$ 48.6	$ 92.9	$ 199.1
Basic Earnings (Loss) Per Share ($)
Continuing Operations	$ 0.05	$ (0.05)	$ 0.42	$ 0.56
Discontinued operations	(0.07)	0.15	0.30	0.63
Basic Earnings Per Share	(0.02)	0.10	0.72	1.19
Diluted Earnings (Loss) Per Share ($)
Continuing operations	0.05	(0.05)	0.42	0.56
Discontinued operations	(0.07)	0.15	0.29	0.63
Earnings Per Share, Diluted	(0.02)	0.10	0.71	1.19
Dividends Declared Per Common Share	$ 0.31	$ 0.26	$ 0.83	$ 1.02
Basic Average Common Shares Outstanding	318,090	315,418	317,390	314,889
Diluted Average Common Shares	321,465	315,418	320,718	316,006

Statements of Consolidated Comp

Statements of Consolidated Comprehensive Income - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net (Loss) Income		$ (4.9)	$ 31.4	$ 242.7	$ 375.8
Net unrealized (loss) gain on available-for-sale securities	[1]	0.3	(0.6)	0	0.2
Net unrealized gain on cash flow hedges	[2]	0.2	0.6	1.8	1.9
Unrecognized pension and OPEB (cost) benefit	[3]	(0.2)	(0.2)	2.7	(0.1)
Total other comprehensive income (loss)		0.3	(0.2)	4.5	2
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest		(4.6)	31.2	247.2	377.8
Less: Net income attributable to noncontrolling interest		0	0	15.6	0
Comprehensive (Loss) Income attributable to NiSource		(4.6)	31.2	231.6	377.8
Parent Company [Member]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax		0.2	(0.3)	0	0.1
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax		0.2	0.4	1.1	1.2
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax		$ (0.1)	$ 0	$ 2.1	$ (0.7)
[1]	Net unrealized gain (loss) on available-for-sale securities, net of $0.2 million tax expense and $0.3 million tax benefit in the third quarter of 2015 and 2014, respectively, and zero and $0.1 million tax expense for the first nine months of 2015 and 2014, respectively.
[2]	Net unrealized gains on derivatives qualifying as cash flow hedges, net of $0.2 million and $0.4 million tax expense in the third quarter of 2015 and 2014, respectively, and $1.1 million and $1.2 million tax expense for the first nine months of 2015 and 2014, respectively.
[3]	Unrecognized pension and OPEB (cost) benefit net of $0.1 million and zero tax benefit in the third quarter of 2015 and 2014, respectively, and $2.1 million tax expense and $0.7 million tax benefit for the first nine months of 2015 and 2014, respectively.

Statements of Consolidated Com4

Statements of Consolidated Comprehensive Income (Parenthetical) - Parent Company [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	$ 0.2	$ (0.3)	$ 0	$ 0.1
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	0.2	0.4	1.1	1.2
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax	$ (0.1)	$ 0	$ 2.1	$ (0.7)

Statements of Consolidated Bala

Statements of Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment
Utility Plant	$ 18,484.8	$ 17,668.4
Accumulated depreciation and amortization	(6,811.5)	(6,629.5)
Net utility plant	11,673.3	11,038.9
Other property, at cost, less accumulated depreciation	17.4	18.5
Net Property, Plant and Equipment	11,690.7	11,057.4
Investments and Other Assets
Unconsolidated affiliates	6.7	8.3
Other investments	195.8	204.8
Total Investments and Other Assets	202.5	213.1
Current Assets
Cash and cash equivalents	31.7	24.9
Restricted Cash	27.9	24.9
Accounts receivable (less reserve of $20.7 and $24.9, respectively)	500.5	920.8
Gas inventory	398.9	440.3
Underrecovered gas and fuel costs	7.1	32
Materials and supplies, at average cost	84.2	81.1
Electric production fuel, at average cost	81.1	64.8
Exchange gas receivable	19.7	28.3
Disposal Group, Including Discontinued Operation, Assets, Current	0	341.3
Regulatory assets	183.7	187.4
Deferred Tax Assets, Net, Current	227.1	214.2
Prepayments and other	75.9	106.5
Total Current Assets	1,637.8	2,466.5
Other Assets
Regulatory assets	1,507.5	1,544.5
Goodwill	1,690.7	1,690.7
Intangible assets	256.4	264.7
Disposal Group, Including Discontinued Operation, Assets, Noncurrent	0	7,546
Deferred charges and other	70.3	83.4
Total Other Assets	3,524.9	11,129.3
Total Assets	17,055.9	24,866.3
Common Stockholders' Equity
Common stock - $0.01 par value, 400,000,000 shares authorized; 318,474,781 and 316,037,421 shares outstanding, respectively	3.2	3.2
Additional paid-in capital	5,078.6	4,787.6
Retained earnings	(1,182.7)	1,494
Accumulated other comprehensive loss	(19.6)	(50.6)
Treasury stock	(79.2)	(58.9)
Total Common Stockholders' Equity	3,800.3	6,175.3
Long-term debt, excluding amounts due within one year	6,133.5	8,155.9
Total Capitalization	9,933.8	14,331.2
Current Liabilities
Current portion of long-term debt	442.6	266.6
Short-term borrowings	107.2	1,576.9
Accounts payable	349.2	610.1
Dividends payable	49.3	0
Customer deposits and credits	255.4	280.9
Taxes accrued	137	169.2
Interest accrued	77.5	140.7
Overrecovered gas and fuel costs	169.2	45.6
Exchange gas payable	66.8	101.5
Deferred revenue	9.3	3.4
Regulatory liabilities	120.2	61.1
Accrued liability for postretirement and postemployment benefits	5.2	5.3
Disposal Group, Including Discontinued Operation, Liabilities, Current	0	369
Legal and environmental	36.8	22.7
Employee-related Liabilities, Current	125.9	166.8
Other accruals	121.7	144.5
Total Current Liabilities	2,073.3	3,964.3
Other Liabilities and Deferred Credits
Deferred income taxes	2,513.9	2,380
Deferred investment tax credits	15.4	17.1
Deferred credits	99.4	100.9
Accrued liability for postretirement and postemployment benefits	665.2	733.9
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent	0	1,616.3
Regulatory liabilities	1,387.1	1,379.6
Asset retirement obligations	181.2	136.2
Other noncurrent liabilities	186.6	206.8
Total Other Liabilities and Deferred Credits	5,048.8	6,570.8
Commitments and Contingencies	0	0
Total Capitalization and Liabilities	$ 17,055.9	$ 24,866.3

Statements of Consolidated Bal6

Statements of Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Accounts receivable less reserve	$ 20.7	$ 24.9
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000	400,000,000
Common Stock, Shares, Outstanding	318,474,781	316,037,421

Statements Of Consolidated Cash

Statements Of Consolidated Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating Activities
Net (Loss) Income	$ 242.7	$ 375.8
Adjustments to Reconcile Net Income to Net Cash from Continuing Operations:
Payments of Debt Extinguishment Costs	97.2	0
Depreciation and amortization	391	363.1
Net changes in price risk management assets and liabilities	2	1.9
Deferred income taxes and investment tax credits	60.1	110.1
Deferred revenue	7.3	(0.4)
Stock compensation expense and 401(k) profit sharing contribution	38.6	50.2
Loss on sale of assets	1.2	1.5
Income from unconsolidated affiliates	0.8	0.6
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	(108.5)	(199.1)
Amortization of debt related costs	6.8	7.5
AFUDC equity	(7.7)	(7.4)
Changes in Assets and Liabilities:
Accounts receivable	420.3	360.3
Inventories	19.8	(170.5)
Accounts payable	(287.5)	(228.7)
Customer deposits and credits	(25.5)	(5)
Taxes accrued	(30.6)	(31.1)
Interest accrued	(63.1)	(54.7)
Over (Under) recovered gas and fuel costs	148.5	(19.2)
Exchange gas receivable/payable	(26.1)	(57.2)
Other accruals	(57.1)	(29.5)
Prepayments and other current assets	30.1	33.9
Regulatory assets/liabilities	111.1	(18.1)
Postretirement and postemployment benefits	(61)	(86.7)
Deferred credits	(1.3)	10.7
Deferred charges and other noncurrent assets	10.8	5.5
Other noncurrent liabilities	(13.6)	5.3
Net Operating Activities from Continuing Operations	906.3	418.8
Net Operating Activities from Discontinued Operations	287.6	467.7
Net Cash Flows from Operating Activities	1,193.9	886.5
Investing Activities
Capital expenditures	(923.4)	(914.3)
Proceeds from disposition of assets	4.3	1.6
Restricted cash deposits	(3)	(8.1)
Cash contributions from CPG	3,798.2	0
Other investing activities	(39.9)	(7.4)
Net Investing Activities from (used for) Continuing Operations	2,836.2	(928.2)
Cash Provided by (Used in) Investing Activities, Discontinued Operations	(430)	(584)
Net Cash Flows from (used for) Investing Activities	2,406.2	(1,512.2)
Financing Activities
Proceeds from Issuance of Common Limited Partners Units	(136.8)	0
Issuance of long-term debt	0	748.4
Repayments of long-term debt and capital lease obligations	(1,859.1)	(517.1)
Proceeds from (Payments for) Other Financing Activities	(93.5)	0
Change in short-term borrowings, net	(1,396.6)	612.3
Issuance of common stock	17.9	22.4
Acquisition of treasury stock	(20.3)	(10.2)
Dividends paid - common stock	(214)	(239.2)
Net Cash Provided by (Used in) Financing Activities, Continuing Operations	(3,702.4)	616.6
Cash Provided by (Used in) Financing Activities, Discontinued Operations	108.6	0
Net Cash Flows from (used for) Financing Activities	(3,593.8)	616.6
Change in cash and cash equivalents from continuing operations	40.1	107.2
Change in cash and cash equivalents from discontinued operations	(33.8)	(116.3)
Change in cash included in discontinued operations	0.5	(0.1)
Cash and cash equivalents at beginning of period	24.9	26.5
Cash and Cash Equivalents at End of Period	$ 31.7	$ 17.3

Statements Of Consolidated Comm

Statements Of Consolidated Common Stockholders' Equity - 9 months ended Sep. 30, 2015 - USD ($) $ in Millions		Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2014		$ 6,175.3	$ 3.2	$ (58.9)	$ 4,787.6	$ 1,494	$ (50.6)
Net Income (Loss) Attributable to Parent		227.1	0	0	0	227.1	0
Other comprehensive income, net of tax		4.5	0	0	0	0	4.5
Allocation of AOCI to Noncontrolling Interest	[1]	2	0	0	0	0	2
Common stock dividends ($0.83 per share)		(263.5)	0	0	0	(263.5)	0
Stockholders' Equity Note, Spinoff Transaction		(2,615.8)	0	0	0	(2,640.3)	24.5
Treasury stock acquired		(20.3)	0	(20.3)	0	0	0
Employee stock purchase plan		4	0	0	4	0	0
Long-term incentive plan		17	0	0	17	0	0
401(k) and profit sharing issuance		36.7	0	0	36.7	0	0
Dividend reinvestment plan		6.2	0	0	6.2	0	0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	[1],[2]	227.1	0	0	227.1	0	0
Ending Balance at Sep. 30, 2015		$ 3,800.3	$ 3.2	$ (79.2)	$ 5,078.6	$ (1,182.7)	$ (19.6)
[1]	This transaction, which occurred prior to the Separation, was distributed through retained earnings as part of the Separation on July 1, 2015.
[2]	Represents the purchase of an additional 8.4% limited partner interest in Columbia OpCo by an affiliate of CPG, recorded at the historical carrying value of Columbia OpCo's net assets after giving effect to the $1,168.4 million equity contribution from CPPL's IPO completed on February 11, 2015.

Statements Of Consolidated Com9

Statements Of Consolidated Common Stockholders' Equity (Parenthetical) - USD ($) $ in Millions	Feb. 11, 2015	Sep. 30, 2015
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest		8.40%
Proceeds from Issuance Initial Public Offering	$ 1,168.4
Dividends Declared Per Common Share		$ 0.83

Basis of Accounting Presentatio

Basis of Accounting Presentation	9 Months Ended
	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting Presentation	Basis of Accounting Presentation The accompanying Condensed Consolidated Financial Statements (unaudited) for NiSource Inc. ("NiSource" or the “Company”) reflect all normal recurring adjustments that are necessary, in the opinion of management, to present fairly the results of operations in accordance with GAAP in the United States of America. The accompanying financial statements contain the accounts of the Company and its majority-owned or controlled subsidiaries. The results of operations of the former Columbia Pipeline Group Operations segment have been classified as discontinued operations for all periods presented. See Note 4, "Discontinued Operations," for further information. Unless otherwise indicated, the information in the Notes to the Condensed Consolidated Financial Statements (unaudited) relates to NiSource's continuing operations. The accompanying financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in NiSource’s Annual Report on Form 10-K for the fiscal year ended December 31, 2014 . Income for interim periods may not be indicative of results for the calendar year due to weather variations and other factors. The Condensed Consolidated Financial Statements (unaudited) have been prepared pursuant to the rules and regulations of the SEC. Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations, although NiSource believes that the disclosures made in this quarterly report on Form 10-Q are adequate to make the information herein not misleading.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	9 Months Ended
	Sep. 30, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements In July 2015, the FASB issued ASU 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory . ASU 2015-11 replaces the current lower of cost or market test with a lower of cost or net realizable value test. The new standard applies only to inventories for which cost is determined by methods other than LIFO and the retail inventory method (RIM). NiSource is required to adopt ASU 2015-11 for periods beginning after December 15, 2016, including interim periods, with early adoption permitted. NiSource is currently evaluating the impact the adoption of ASU 2015-11 will have on the Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited). In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606) . ASU 2014-09 outlines a single, comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. The core principle of the new standard is that an entity should recognize revenue to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In July 2015, the FASB deferred the effective date for ASU 2014-09 to annual reporting periods beginning after December 15, 2017, including interim periods. Companies are permitted to adopt ASU 2014-09 on the original effective date of the ASU. NiSource is currently evaluating the impact the adoption of ASU 2014-09 will have on its Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited). In April 2015, the FASB issued ASU 2015-05, Intangibles - Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer's Accounting for Fees Paid in a Cloud Computing Arrangement. ASU 2015-05 clarifies guidance on determining whether a cloud computing arrangement contains a software license that should be accounted for as internal-use software. NiSource is required to adopt ASU 2015-05 for periods beginning after December 15, 2015, including interim periods, and the guidance is permitted to be applied either (1) prospectively to all agreements entered into or materially modified after the effective date or (2) retrospectively, with early adoption permitted. NiSource is currently evaluating the impact the adoption of ASU 2015-05 will have on the Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited). In April 2015, the FASB issued ASU 2015-03, Interest - Imputation of Interest (Subtopic 835-30) : Simplifying the Presentation of Debt Issuance Costs . ASU 2015-03 changes the way entities present debt issuance costs in financial statements by presenting issuance costs on the balance sheet as a direct deduction from the related debt liability rather than as a deferred charge. Amortization of these costs will continue to be reported as interest expense. NiSource is required to adopt ASU 2015-03 for periods beginning after December 15, 2015, including interim periods, and the guidance is to be applied retrospectively with early adoption permitted. NiSource is currently evaluating the impact the adoption of ASU 2015-03 will have on the Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited).

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share Basic EPS is computed by dividing net income attributable to NiSource by the weighted-average number of shares of common stock outstanding for the period. The weighted-average shares outstanding for diluted EPS includes the incremental effects of the various long-term incentive compensation plans. The numerator in calculating both basic and diluted EPS for each period is reported net income attributable to NiSource. The computation of diluted average common shares for the three months ended September 30, 2014 is not presented since NiSource had a loss from continuing operations on the Condensed Statements of Consolidated (Loss) Income (unaudited) during the period and any incremental shares would have an antidilutive effect on EPS. The computation of diluted average common shares is as follows: Three Months Ended Nine Months Ended September 30, September 30, (in thousands) 2015 2015 2014 Denominator Basic average common shares outstanding 318,090 317,390 314,889 Dilutive potential common shares: Stock options — — 30 Shares contingently issuable under employee stock plans — — 649 Shares restricted under stock plans (1) 3,375 3,328 438 Diluted Average Common Shares 321,465 320,718 316,006 (1) Change due to Separation-related adjustments, see Note 15, "Share-Based Compensation."

Discontinued Operations

Discontinued Operations	9 Months Ended
	Sep. 30, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operations [Abstract]	On July 1, 2015, NiSource completed the Separation of CPG from NiSource through a special pro rata stock dividend, distributing one share of CPG common stock for every one share of NiSource common stock held by any NiSource stockholder on June 19, 2015, the record date. The Separation resulted in two stand-alone energy infrastructure companies: NiSource, a fully regulated natural gas and electric utilities company, and CPG, a natural gas pipeline, midstream and storage company. As a stand-alone company, CPG's operations consist of substantially all of NiSource's Columbia Pipeline Group Operations segment prior to the Separation. NiSource retained no ownership interest in CPG. On the date of the Separation, CPG consisted of approximately $9.2 billion of assets, $5.6 billion of liabilities and $3.6 billion of equity. The results of operations and cash flows for the former Columbia Pipeline Group Operations segment have been reported as discontinued operations for all periods presented. Additionally, the assets and liabilities of the former Columbia Pipeline Group Operations segment were reclassified as assets and liabilities of discontinued operations for all prior periods. Results from discontinued operations are provided in the following table. These results are primarily from NiSource's former Columbia Pipeline Group Operations segment. Three Months Ended Nine Months Ended September 30, 2015 September 30, 2015 (in millions) Columbia Pipeline Group Operations Corporate and Other Total Columbia Pipeline Group Operations Corporate and Other Total Net Revenues Transportation and storage revenues $ — $ — $ — $ 561.4 $ — $ 561.4 Other revenues — — — 94.3 — 94.3 Total Sales Revenues — — — 655.7 — 655.7 Less: Cost of sales (excluding depreciation and amortization) — — — 0.2 — 0.2 Net Revenues — — — 655.5 — 655.5 Operating Expenses Operation and maintenance 5.5 (1) — 5.5 374.8 (1) — 374.8 Depreciation and amortization — — — 66.4 — 66.4 Gain on sale of assets — — — (13.6 ) — (13.6 ) Other taxes — — — 38.0 — 38.0 Total Operating Expenses 5.5 — 5.5 465.6 — 465.6 Equity Earnings in Unconsolidated Affiliates — — — 29.1 — 29.1 Operating (Loss) Income from discontinued operations (5.5 ) — (5.5 ) 219.0 — 219.0 Other Income (Deductions) Interest expense, net — — — (37.1 ) — (37.1 ) Other, net — — — 7.8 (0.6 ) 7.2 Total Other Deductions — — — (29.3 ) (0.6 ) (29.9 ) (Loss) Income from Discontinued Operations before Income Taxes (5.5 ) — (5.5 ) 189.7 (0.6 ) 189.1 Income Taxes 14.2 (2) — 14.2 80.9 (0.3 ) 80.6 (Loss) Income from Discontinued Operations - net of taxes $ (19.7 ) $ — $ (19.7 ) $ 108.8 $ (0.3 ) $ 108.5 (1) Includes approximately $5.5 million and $54.4 million for the three and nine months ended September 30, 2015, of transaction costs related to the Separation. (2) Primarily attributable to the write-off of consolidated state income tax benefits resulting from the Separation. Three Months Ended Nine Months Ended September 30, 2014 September 30, 2014 (in millions) Columbia Pipeline Group Operations Corporate and Other Total Columbia Pipeline Group Operations Corporate and Other Total Net Revenues Transportation and storage revenues $ 243.1 $ — $ 243.1 $ 746.1 $ — $ 746.1 Other revenues 74.5 — 74.5 260.6 — 260.6 Total Sales Revenues 317.6 — 317.6 1,006.7 — 1,006.7 Less: Cost of sales (excluding depreciation and amortization) — — — 0.2 — 0.2 Net Revenues 317.6 — 317.6 1,006.5 — 1,006.5 Operating Expenses Operation and maintenance 202.1 (1) — 202.1 573.3 (1) — 573.3 Depreciation and amortization 29.2 — 29.2 87.7 — 87.7 Gain on sale of assets (3.0 ) — (3.0 ) (20.8 ) — (20.8 ) Other taxes 14.6 — 14.6 50.3 — 50.3 Total Operating Expenses 242.9 — 242.9 690.5 — 690.5 Equity Earnings in Unconsolidated Affiliates 12.0 — 12.0 32.9 — 32.9 Operating Income from discontinued operations 86.7 — 86.7 348.9 — 348.9 Other Income (Deductions) Interest expense, net (14.9 ) — (14.9 ) (40.4 ) — (40.4 ) Other, net 3.5 (0.2 ) 3.3 7.8 (1.0 ) 6.8 Total Other Deductions (11.4 ) (0.2 ) (11.6 ) (32.6 ) (1.0 ) (33.6 ) Income (Loss) from Discontinued Operations before Income Taxes 75.3 (0.2 ) 75.1 316.3 (1.0 ) 315.3 Income Taxes 26.6 (0.1 ) 26.5 116.6 (0.4 ) 116.2 Income (Loss) from Discontinued Operations - net of taxes $ 48.7 $ (0.1 ) $ 48.6 $ 199.7 $ (0.6 ) $ 199.1 (1) Includes approximately $9.3 million and $12.8 million for the three and nine months ended September 30, 2014, of transaction costs related to the Separation. CPG’s financing requirements prior to the private placement of senior notes on May 22, 2015 were satisfied through borrowings from NiSource Finance. Interest expense from discontinued operations primarily represents net interest charged to CPG from NiSource Finance, less AFUDC. Subsequent to May 22, 2015, interest expense from discontinued operations also includes interest incurred on CPG’s private placement of $2,750.0 million of senior notes. Continuing Involvement Natural gas transportation and storage services provided to NiSource by CPG were $31.6 million and $105.4 million for the three and nine months ended September 30, 2015 and $31.9 million and $106.3 million for the three and nine months ended September 30, 2014. Prior to July 1, 2015, these costs were eliminated in consolidation. Beginning July 1, 2015, these costs and associated cash flows represent third-party transactions with CPG and are not eliminated in consolidation, as such services have continued subsequent to the Separation and are expected to continue for the foreseeable future. As a result of the Separation, NiSource and CPG entered into a Transition Services Agreement (TSA). NiSource expects the TSA to terminate within 18 months from the date of the Separation. The TSA sets forth the terms and conditions for NiSource and CPG to provide certain transition services to one another. NiSource will provide CPG certain information technology, financial and accounting, human resource and other specified services. For the period July 1, 2015 to September 30, 2015, the amounts NiSource billed CPG for these services were not significant. There were no assets and liabilities of discontinued operations on the Condensed Consolidated Balance Sheet (unaudited) at September 30, 2015. The assets and liabilities of discontinued operations on the Condensed Consolidated Balance Sheet (unaudited) at December 31, 2014 were: December 31, 2014 (in millions) Columbia Pipeline Group Operations Current Assets Cash and cash equivalents $ 0.5 Accounts receivable, net 149.3 Gas inventory 4.8 Materials and supplies, at average cost 24.9 Exchange gas receivable 34.8 Regulatory assets 6.1 Deferred income taxes 57.9 Prepayments and other 63.0 Total current assets $ 341.3 Noncurrent Assets Net property, plant and equipment $ 4,959.7 Goodwill 1,975.5 Unconsolidated affiliates 444.3 Other investments 5.6 Regulatory assets 151.9 Deferred charges and other 9.0 Total noncurrent assets $ 7,546.0 December 31, 2014 (in millions) Columbia Pipeline Group Operations Current Liabilities Accounts payable $ 60.5 Customer deposits and credits 13.4 Taxes accrued 106.9 Exchange gas payable 34.7 Deferred revenue 22.2 Regulatory liabilities 1.3 Accrued liability for postretirement and postemployment benefits 0.6 Legal and environmental 1.5 Accrued capital expenditures 61.1 Other accruals 66.8 Total current liabilities $ 369.0 Noncurrent Liabilities Deferred income taxes $ 1,272.2 Deferred investment tax credits 0.2 Deferred credits 0.2 Accrued liability for postretirement and postemployment benefits (1) (58.0 ) Regulatory liabilities 294.2 Asset retirement obligations 23.2 Other noncurrent liabilities 84.3 Total noncurrent liabilities $ 1,616.3 (1) Represents Columbia Pipeline Group segment's overfunded position in NiSource's net underfunded other postretirement plan.

Asset Retirement Obligations

Asset Retirement Obligations	9 Months Ended
	Sep. 30, 2015
Asset Retirement Obligation [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations Certain costs of removal that have been, and continue to be, included in depreciation rates and collected in the service rates of the rate-regulated subsidiaries are classified as “Regulatory liabilities” on the Condensed Consolidated Balance Sheets (unaudited). Changes in NiSource’s liability for asset retirement obligations for the nine months ended September 30, 2015 and 2014 are presented in the table below: (in millions) 2015 2014 Balance as of January 1, $ 136.2 $ 148.1 Accretion recorded as a regulatory asset/liability 5.9 6.3 Additions 6.4 0.3 Settlements (4.3 ) (1.3 ) Change in estimated cash flows (1) 37.0 (7.4 ) Balance as of September 30, $ 181.2 $ 146.0 (1) The current year change in estimated cash flows is primarily attributable to estimated costs associated with the EPA's final rule for regulation of CCRs and changes to cost estimates for certain solid waste management units. See Note 16, "Other Commitments and Contingencies," for additional information on CCRs.

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2015
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Matters	Regulatory Matters Gas Distribution Operations Regulatory Matters Significant Rate Developments . On November 25, 2014, Columbia of Ohio filed a Notice of Intent to file an application to adjust rates associated with its IRP and DSM Riders. Columbia of Ohio filed its Application on February 27, 2015, and requested authority to increase revenues by $24.7 million . On March 26, 2015, PUCO Staff filed Comments recommending that the PUCO approve Columbia of Ohio’s application in full. On April 22, 2015, the PUCO issued an Order that approved Columbia of Ohio's application. New rates went into effect on May 1, 2015. On March 19, 2015, Columbia of Pennsylvania filed a base rate case with the Pennsylvania PUC, seeking a revenue increase of $46.2 million annually. The case is driven by Columbia of Pennsylvania’s capital investment program which exceeds $197.0 million in 2015 and $211.0 million in 2016 as well as costs to train and comply with pipeline safety-related operation and maintenance expenditures. Columbia of Pennsylvania's request for rate relief includes the recovery of costs that are projected to be incurred after the implementation of new rates, as authorized by the Pennsylvania General Assembly with the passage of Act 11 of 2012. On August 27, 2015, the parties to the case filed a joint petition for approval of a settlement that features an annual revenue increase of $28.0 million . New rates are expected to go into effect during the fourth quarter of 2015. On April 16, 2015, Columbia of Massachusetts filed a base rate case with the Massachusetts DPU. The case, which sought increased annual revenues of approximately $49.0 million , was designed to support Columbia of Massachusetts' continued focus on providing safe and reliable service in compliance with increasing state and federal regulations and oversight, and recovery of associated increased operations and maintenance costs. Columbia of Massachusetts arrived at a settlement agreement with the Massachsuetts Attorney General in the case which was filed for approval with the Massachusetts DPU on August 19, 2015 and approved on October 7, 2015. The settlement agreement provides for increased annual revenues of $32.8 million beginning November 1, 2015, with an additional $3.6 million annual increase in revenues starting November 1, 2016. The settlement also provides that Columbia of Massachusetts cannot increase base distribution rates to become effective prior to November 1, 2018. On April 30, 2014, Columbia of Virginia filed a base rate case with the VSCC seeking an annual revenue increase of $31.8 million . New rates went into effect in October 2014, subject to refund. On December 10, 2014, Columbia of Virginia presented at hearing a Stipulation and Proposed Recommendation (“Stipulation”) executed by certain parties to the rate proceeding that included a base revenue increase of $25.2 million including recovery of costs related to the implementation of pipeline safety programs. On March 30, 2015, the VSCC issued an Order Remanding for Further Action approving the revenue increase of $25.2 million contained in the Stipulation, but remanding for further proceedings the single issue of the manner in which fixed costs were to be assigned to the fixed customer charges of each rate class. Following a hearing, the VSCC on August 21, 2015 issued a Final Order resolving the fixed customer charge and allowing Columbia of Virginia to implement new rates. Cost Recovery and Trackers . A significant portion of the NiSource distribution companies' revenue is related to the recovery of gas costs, the review and recovery of which occur via standard regulatory proceedings. All states require periodic review of actual gas procurement activity to determine prudence and to permit the recovery of prudently incurred costs related to the supply of gas for customers. NiSource distribution companies have historically been found prudent in the procurement of gas supplies to serve customers. Certain operating costs of the NiSource distribution companies are significant, recurring in nature, and generally outside the control of the distribution companies. Some states allow the recovery of such costs via cost tracking mechanisms. Such tracking mechanisms allow for abbreviated regulatory proceedings in order for the distribution companies to implement charges and recover appropriate costs. Tracking mechanisms allow for more timely recovery of such costs as compared with more traditional cost recovery mechanisms. Examples of such tracking mechanisms include GCR adjustment mechanisms, tax riders, and bad debt recovery mechanisms. Comparability of Gas Distribution Operations line item operating results is impacted by regulatory trackers that allow for the recovery in rates of certain costs such as bad debt expense. Increases in the expenses that are the subject of trackers, result in a corresponding increase in net revenues and therefore have essentially no impact on total operating income results. Certain of the NiSource distribution companies have completed rate proceedings involving infrastructure replacement or are embarking upon regulatory initiatives to replace significant portions of their operating systems that are nearing the end of their useful lives. Each LDC's approach to cost recovery may be unique, given the different laws, regulations and precedent that exist in each jurisdiction. NIPSCO has approval from the IURC to recover certain costs for gas transmission, distribution and storage system improvements. On February 27, 2015, NIPSCO filed gas TDSIC-2 which included $43.3 million of net capital expenditures for the period ended December 31, 2014. Given the Indiana Court of Appeals decision in NIPSCO's electric TDSIC filing (for further information, see "Electric Operations Regulatory Matters" below), NIPSCO elected to dismiss its TDSIC-2 filing in favor of supplying further detailed plan updates in the next proceeding, TDSIC-3. On August 31, 2015, NIPSCO filed TDSIC-3 which included $75.2 million of net capital expenditures for the period ended June 30, 2015. An order is expected in the first quarter of 2016. Electric Operations Regulatory Matters Significant Rate Developments . On July 19, 2013, NIPSCO filed its electric TDSIC with the IURC. The filing included the seven-year plan of eligible investments for a total of approximately $1.1 billion with the majority of the spend occurring in years 2016 through 2020. On February 17, 2014, the IURC issued an order approving NIPSCO’s seven-year plan of eligible investments. The order also granted NIPSCO ratemaking relief associated with the eligible investments through a rate adjustment mechanism. The NIPSCO Industrial Group and the OUCC filed Notices of Appeal with the Indiana Court of Appeals in response to the IURC's ruling. On November 25, 2014, NIPSCO’s requested TDSIC factors were approved on an interim basis and subject to refund, pending the outcome of the appeals of the IURC’s February 17, 2014 Orders. On April 8, 2015, the Court of Appeals issued an order concluding that the IURC erred in approving NIPSCO’s seven-year plan given its lack of detail regarding the projects for years two through seven. The court then remanded the decision to the IURC. On May 26, 2015, NIPSCO filed a settlement on remand which, among other things, requires NIPSCO to file an electric base rate case proceeding by December 31, 2015 and a new seven-year electric TDSIC plan following the filing of its next general rate case proceeding. The settlement agreement was rejected by the IURC on September 23, 2015. The settling parties filed a Petition for Rehearing on September 29, 2015 and were granted a rehearing which was held on October 28, 2015. On October 1, 2015, NIPSCO filed an electric base rate case with the IURC, seeking a revenue increase of approximately $148.0 million . As part of this filing, NIPSCO is proposing to update base rates for previously incurred infrastructure improvements, revised depreciation rates, and the inclusion of previously approved environmental and federally mandated compliance costs. A prehearing conference was held on October 29, 2015 and a final order is anticipated in the second half of 2016. Cost Recovery and Trackers . A significant portion of NIPSCO's revenue is related to the recovery of fuel costs to generate power and the fuel costs related to purchased power. These costs are recovered through a FAC, a standard, quarterly, “summary” regulatory proceeding in Indiana. Certain operating costs of the Electric Operations are significant, recurring in nature, and generally outside the control of NIPSCO. The IURC allows for recovery of such costs via cost tracking mechanisms. Such tracking mechanisms allow for abbreviated regulatory proceedings in order for NIPSCO to implement charges and recover appropriate costs. Tracking mechanisms allow for more timely recovery of such costs as compared with more traditional cost recovery mechanisms. Examples of such mechanisms include electric energy efficiency programs, MISO non-fuel costs and revenues, resource capacity charges, and environmental related costs. NIPSCO has approval from the IURC to recover certain environmental related costs through an ECT. Under the ECT, NIPSCO is permitted to recover (1) AFUDC and a return on the capital investment expended by NIPSCO to implement environmental compliance plan projects through an ECRM and (2) related operation and maintenance and depreciation expenses once the environmental facilities become operational through an EERM. On October 21, 2015, the IURC issued an order on ECR-26 approving NIPSCO’s request to begin earning a return on $776.5 million of net capital expenditures for the period ended June 30, 2015. The order also approved a revised capital cost estimate of $255.3 million for its Phase III multi-pollutant compliance plan projects related to the Michigan City Unit 12 FGD, a decrease from the previous IURC approved cost estimate of $264.8 million .

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value	Fair Value A. Fair Value Measurements Recurring Fair Value Measurements. The following tables present financial assets and liabilities measured and recorded at fair value on NiSource’s Condensed Consolidated Balance Sheets (unaudited) on a recurring basis and their level within the fair value hierarchy as of September 30, 2015 and December 31, 2014 : Recurring Fair Value Measurements September 30, 2015 (in millions) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Balance as of September 30, 2015 Assets Price risk management assets: Commodity financial price risk programs $ 0.1 $ — $ — $ 0.1 Available-for-sale securities 34.0 101.4 — 135.4 Total $ 34.1 $ 101.4 $ — $ 135.5 Liabilities Price risk management liabilities: Commodity financial price risk programs $ 16.3 $ — $ 0.6 $ 16.9 Total $ 16.3 $ — $ 0.6 $ 16.9 Recurring Fair Value Measurements (in millions) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Balance as of December 31, 2014 Assets Price risk management assets: Commodity financial price risk programs $ 0.1 $ — $ — $ 0.1 Available-for-sale securities 28.4 103.5 — 131.9 Total $ 28.5 $ 103.5 $ — $ 132.0 Liabilities Price risk management liabilities: Commodity financial price risk programs $ 14.2 $ — $ 0.1 $ 14.3 Total $ 14.2 $ — $ 0.1 $ 14.3 Price risk management assets and liabilities primarily include NYMEX futures and NYMEX options which are commodity exchange-traded and non-exchange-based derivative contracts. Exchange-traded derivative contracts are based on unadjusted quoted prices in active markets and are classified within Level 1. These financial assets and liabilities are secured with cash on deposit with the exchange; therefore nonperformance risk has not been incorporated into these valuations. Certain non-exchange-traded derivatives are valued using broker or over-the-counter, on-line exchanges. In such cases, these non-exchange-traded derivatives are classified within Level 2. Non-exchange-based derivative instruments include swaps, forwards, and options. In certain instances, these instruments may utilize models to measure fair value. NiSource uses a similar model to value similar instruments. Valuation models utilize various inputs that include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, other observable inputs for the asset or liability, and market-corroborated inputs, (i.e., inputs derived principally from or corroborated by observable market data by correlation or other means). Where observable inputs are available for substantially the full term of the asset or liability, the instrument is categorized in Level 2. Certain derivatives trade in less active markets with a lower availability of pricing information and models may be utilized in the valuation. When such inputs have a significant impact on the measurement of fair value, the instrument is categorized in Level 3. Credit risk is considered in the fair value calculation of derivative instruments that are not exchange-traded. Credit exposures are adjusted to reflect collateral agreements which reduce exposures. As of September 30, 2015 and December 31, 2014 , there were no material transfers between fair value hierarchies. Additionally, there were no changes in the method or significant assumptions used to estimate the fair value of NiSource’s financial instruments. Commodity price risk resulting from derivative activities at NiSource’s rate-regulated subsidiaries is limited, since regulations allow recovery of prudently incurred purchased power, fuel and gas costs through the ratemaking process, including gains or losses on these derivative instruments. If states should explore additional regulatory reform, these subsidiaries may begin providing services without the benefit of the traditional ratemaking process and may be more exposed to commodity price risk. Some of NiSource’s rate-regulated utility subsidiaries offer commodity price risk products to its customers for which derivatives are used to hedge forecasted customer usage under such products. These subsidiaries do not have regulatory recovery orders for these products and are subject to gains and losses recognized in earnings due to hedge ineffectiveness. Available-for-sale securities are investments pledged as collateral for trust accounts related to NiSource’s wholly-owned insurance company. Available-for-sale securities are included within “Other investments” in the Condensed Consolidated Balance Sheets (unaudited). Securities classified within Level 1 include U.S. Treasury debt securities which are highly liquid and are actively traded in over-the-counter markets. NiSource values corporate and mortgage-backed debt securities using a matrix pricing model that incorporates market-based information. These securities trade less frequently and are classified within Level 2. Total unrealized gains and losses from available-for-sale securities are included in other comprehensive income (loss). The amortized cost, gross unrealized gains and losses and fair value of available-for-sale debt securities at September 30, 2015 and December 31, 2014 were: September 30, 2015 (in millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale debt securities U.S. Treasury securities $ 33.8 $ 0.3 $ — $ 34.1 Corporate/Other bonds 101.0 0.7 (0.4 ) 101.3 Total Available-for-sale debt securities $ 134.8 $ 1.0 $ (0.4 ) $ 135.4 December 31, 2014 (in millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale debt securities U.S. Treasury securities $ 30.8 $ 0.3 $ (0.2 ) $ 30.9 Corporate/Other bonds 100.6 1.0 (0.6 ) 101.0 Total Available-for-sale debt securities $ 131.4 $ 1.3 $ (0.8 ) $ 131.9 For the three months ended September 30, 2015 and 2014 , the net realized gain on the sale of available-for-sale U.S. Treasury debt securities was $0.1 million and zero , respectively. For the three months ended September 30, 2015 and 2014 , the net realized gain on the sale of available-for-sale Corporate/Other bond debt securities was $0.2 million and $0.1 million , respectively. For the nine months ended September 30, 2015 and 2014, the net realized gain on sale of available-for-sale U.S. Treasury debt securities was $0.2 million and $0.1 million , respectively. For the nine months ended September 30, 2015 and 2014, the net realized gain on the sale of available-for-sale Corporate/Other bond debt securities was $0.3 million for each period. The cost of maturities sold is based upon specific identification. At September 30, 2015 , approximately $2.2 million of U.S. Treasury debt securities have maturities of less than a year while the remaining securities have maturities of greater than one year. At September 30, 2015 , approximately $8.7 million of Corporate/Other bonds have maturities of less than a year while the remaining securities have maturities of greater than one year. There are no material items in the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for the three and nine months ended September 30, 2015 and 2014 . Non-recurring Fair Value Measurements. There were no significant non-recurring fair value measurements recorded during the nine months ended September 30, 2015 . B. Other Fair Value Disclosures for Financial Instruments. The carrying amount of cash and cash equivalents, restricted cash, notes receivable, customer deposits and short-term borrowings is a reasonable estimate of fair value due to their liquid or short-term nature. NiSource’s long-term borrowings are recorded at historical amounts. The following methods and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate fair value. Long-term Debt. The fair values of these securities are estimated based on the quoted market prices for the same or similar securities. Certain premium costs associated with the early settlement of long-term debt are not taken into consideration in determining fair value. These fair value measurements are classified as Level 2 within the fair value hierarchy. For the nine months ended September 30, 2015 and 2014 , there were no changes in the method or significant assumptions used to estimate the fair value of the financial instruments. The carrying amount and estimated fair values of financial instruments were as follows: (in millions) Carrying Amount as of September 30, 2015 Estimated Fair Value as of September 30, 2015 Carrying Amount as of Dec. 31, 2014 Estimated Fair Value as of Dec. 31, 2014 Long-term debt (including current portion) $ 6,576.1 $ 7,286.7 $ 8,422.5 $ 9,505.7

Transfers Of Financial Assets

Transfers Of Financial Assets	9 Months Ended
	Sep. 30, 2015
Transfers and Servicing [Abstract]
Transfers Of Financial Assets	Transfers of Financial Assets Transfers of accounts receivable are accounted for as secured borrowings resulting in the recognition of short-term borrowings on the Condensed Consolidated Balance Sheets (unaudited). The maximum amount of debt that can be recognized related to NiSource’s accounts receivable programs is $515 million . All accounts receivables sold to the purchasers are valued at face value, which approximates fair value due to their short-term nature. The amount of the undivided percentage ownership interest in the accounts receivables sold is determined in part by required loss reserves under the agreements. Below is information about the accounts receivable securitization agreements entered into by NiSource’s subsidiaries. Columbia of Ohio is under an agreement to sell, without recourse, substantially all of its trade receivables, as they originate, to CGORC, a wholly-owned subsidiary of Columbia of Ohio. CGORC, in turn, is party to an agreement with BTMU and BNS, under the terms of which it sells an undivided percentage ownership interest in its accounts receivable to commercial paper conduits sponsored by BTMU and BNS. T his agreement was last renewed on October 16, 2015; the current agreement expires on October 15, 2016 and can be further renewed if mutually agreed to by all parties. The maximum seasonal program limit under the terms of the current agreement is $240 million . As of September 30, 2015 , $60.0 million of accounts receivable had been transferred by CGORC. CGORC is a separate corporate entity from NiSource and Columbia of Ohio, with its own separate obligations, and upon a liquidation of CGORC, CGORC’s obligations must be satisfied out of CGORC’s assets prior to any value becoming available to CGORC’s stockholder. NIPSCO is under an agreement to sell, without recourse, substantially all of its trade receivables, as they originate, to NARC, a wholly-owned subsidiary of NIPSCO. NARC, in turn, is party to an agreement with PNC and Mizuho under the terms of which it sells an undivided percentage ownership interest in its accounts receivable to PNC and a commercial paper conduit sponsored by Mizuho. This agreement was last renewed on August 26, 2015; the current agreement expires on August 24, 2016 and can be further renewed if mutually agreed to by all parties. The maximum seasonal program limit under the terms of the current agreement is $200 million . As of September 30, 2015 , $37.2 million of accounts receivable had been transferred by NARC. NARC is a separate corporate entity from NiSource and NIPSCO, with its own separate obligations, and upon a liquidation of NARC, NARC’s obligations must be satisfied out of NARC’s assets prior to any value becoming available to NARC’s stockholder. Columbia of Pennsylvania is under an agreement to sell, without recourse, substantially all of its trade receivables, as they originate, to CPRC, a wholly-owned subsidiary of Columbia of Pennsylvania. CPRC, in turn, is party to an agreement with BTMU under the terms of which it sells an undivided percentage ownership interest in its accounts receivable to a commercial paper conduit sponsored by BTMU. The agreement with BTMU was last renewed on March 10, 2015, having a current scheduled termination date of March 9, 2016 and can be further renewed if mutually agreed to by both parties. The maximum seasonal program limit under the terms of the agreement is $75 million . As of September 30, 2015 , $10.0 million of accounts receivable had been transferred by CPRC. CPRC is a separate corporate entity from NiSource and Columbia of Pennsylvania, with its own separate obligations, and upon a liquidation of CPRC, CPRC’s obligations must be satisfied out of CPRC’s assets prior to any value becoming available to CPRC’s stockholder. The following table reflects the gross and net receivables transferred as well as short-term borrowings related to the securitization transactions as of September 30, 2015 and December 31, 2014 for Columbia of Ohio, NIPSCO and Columbia of Pennsylvania: (in millions) September 30, 2015 December 31, 2014 Gross Receivables $ 347.9 $ 611.7 Less: Receivables not transferred 240.7 327.4 Net receivables transferred $ 107.2 $ 284.3 Short-term debt due to asset securitization $ 107.2 $ 284.3 Columbia of Ohio, NIPSCO and Columbia of Pennsylvania remain responsible for collecting on the receivables securitized and the receivables cannot be sold to another party.

Goodwill

Goodwill	9 Months Ended
	Sep. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets [Table Text Block]	Goodwill The following presents NiSource’s goodwill balance allocated by segment as of September 30, 2015: (in millions) Gas Distribution Operations Electric Operations Corporate and Other Total Goodwill $ 1,690.7 $ — $ — $ 1,690.7 Goodwill previously allocated to the Columbia Pipeline Group Operations segment was disposed of in conjunction with the Separation. For prior periods, such balances are presented within "Assets of discontinued operations" on the Condensed Consolidated Balance Sheets (unaudited). There were no other changes to the goodwill balance during 2015.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective tax rates for the three months ended September 30, 2015 and 2014 were 28.2% and 3.9% , respectively. The effective tax rates for the nine months ended September 30, 2015 and 2014 were 35.8% and 38.7% , respectively. These effective tax rates differ from the Federal tax rate of 35% primarily due to the effects of tax credits, state income taxes, utility ratemaking, and other permanent book-to-tax differences. NiSource’s interim effective tax rates reflect the estimated annual effective tax rates for 2015 and 2014, adjusted for tax expense associated with certain discrete items. The increase in the three month effective tax rate of 24.3% in 2015 versus 2014 is primarily due to the cumulative effect of an estimated annual effective tax rate adjustment resulting from estimated state apportionment changes and other permanent items. The tax rate adjustment in 2015 resulted in a $1.9 million reduction of income tax expense while the 2014 tax rate adjustment resulted in an increase of $4.5 million of income tax expense. The decrease in the year-to-date effective tax rate of 2.9% is primarily due to the impact of the Indiana tax rate change recorded in 2014. There were no material changes recorded in the third quarter of 2015 to NiSource's uncertain tax positions as of December 31, 2014 .

Pension And Other Postretiremen

Pension And Other Postretirement Benefits	9 Months Ended
	Sep. 30, 2015
Pension and Other Postretirement Benefit Expense [Abstract]
Pension And Other Postretirement Benefits	Pension and Other Postretirement Benefits NiSource provides defined contribution plans and noncontributory defined benefit retirement plans that cover its employees. Benefits under the defined benefit retirement plans reflect the employees’ compensation, years of service and age at retirement. Additionally, NiSource provides health care and life insurance benefits for certain retired employees. The majority of employees may become eligible for these benefits if they reach retirement age while working for NiSource. The expected cost of such benefits is accrued during the employees’ years of service. Current rates of rate-regulated companies include postretirement benefit costs, including amortization of the regulatory assets that arose prior to inclusion of these costs in rates. For most plans, cash contributions are remitted to grantor trusts. For the nine months ended September 30, 2015 , NiSource contributed $2.0 million to its pension plans and $18.3 million to its other postretirement benefit plans. The following tables provide the components of the plans’ net periodic benefits cost for the three and nine months ended September 30, 2015 and 2014 : Pension Benefits Other Postretirement Benefits Three Months Ended September 30, (in millions) 2015 2014 2015 2014 Components of Net Periodic Benefit Cost Service cost $ 7.9 $ 7.5 $ 1.4 $ 1.7 Interest cost 22.8 23.8 6.2 5.9 Expected return on assets (37.3 ) (39.3 ) (5.6 ) (5.1 ) Amortization of prior service cost (credit) 0.1 0.3 (1.1 ) (1.4 ) Recognized actuarial loss 13.8 10.2 0.7 0.2 Total Net Periodic Benefit Cost $ 7.3 $ 2.5 $ 1.6 $ 1.3 Pension Benefits Other Postretirement Benefits Nine Months Ended September 30, (in millions) 2015 2014 2015 2014 Components of Net Periodic Benefit Cost Service cost $ 24.3 $ 22.5 $ 4.5 $ 5.7 Interest cost 67.0 71.4 17.8 19.5 Expected return on assets (117.7 ) (117.9 ) (15.6 ) (15.1 ) Amortization of prior service cost (credit) 0.3 0.9 (3.9 ) (2.9 ) Recognized actuarial loss 41.6 30.6 2.8 0.2 Total Net Periodic Benefit Cost $ 15.5 $ 7.5 $ 5.6 $ 7.4 As of July 1, 2015, certain NiSource pension and other postretirement benefit plans were remeasured to account for the Separation of CPG. The remeasurement resulted in an increase to the pension benefit obligation, net of plan assets, of $22.2 million , and net increases to regulatory assets and accumulated other comprehensive loss of $21.1 million and $1.1 million , respectively. Net periodic pension benefit cost for the remainder of 2015 increased by $6.4 million as a result of the remeasurement. The other postretirement benefits obligation, net of plan assets, decreased by $43.6 million as a result of the remeasurement. Additionally, the remeasurement resulted in a decrease to regulatory assets of $34.8 million , an increase to regulatory liabilities of $8.1 million and a decrease to accumulated other comprehensive loss of $0.7 million . Net periodic other postretirement benefit cost for the remainder of 2015 decreased by $0.8 million as a result of the remeasurement. The following table provides the key assumptions that were used to calculate the pension and other postretirement benefits obligation and the net periodic benefit cost at the measurement dates of July 1, 2015 and December 31, 2014. Pension Benefits Other Postretirement Benefits July 1, 2015 December 31, 2014 July 1, 2015 December 31, 2014 Actuarial Assumptions Discount Rate 4.19 % 3.81 % 4.31 % 3.94 % Expected return on assets 8.30 % 8.30 % 8.15 % 8.14 % Health Care Trend Rates Trend for 2015 — — 8.76 % 6.90 % Ultimate Trend — — 4.50 % 4.50 % Year Ultimate Trend Reached — — 2022 2021

Variable Interests and Variable

Variable Interests and Variable Interest Entities	9 Months Ended
	Sep. 30, 2015
Variable Interest Entities And Equity Investments [Abstract]
Variable Interests and Variable Interest Entities	Variable Interests and Variable Interest Entities In general, a VIE is an entity (1) that has an insufficient amount of at-risk equity to permit the entity to finance its activities without additional financial subordinated support provided by any parties, (2) whose at-risk equity owners, as a group, do not have power, through voting rights or similar rights, to direct activities of the entity that most significantly impact the entity’s economic performance or (3) whose at-risk owners do not absorb the entity’s losses or receive the entity’s residual return. A VIE is required to be consolidated by a company if that company is determined to be the primary beneficiary of the VIE. NiSource consolidates those VIEs for which it is the primary beneficiary. NiSource considers quantitative and qualitative elements in determining the primary beneficiary. Qualitative measures include the ability to control an entity and the obligation to absorb losses or the right to receive benefits from such entity. NiSource’s analysis includes an assessment of guarantees, operating leases, purchase agreements, and other contracts, as well as its investments and joint ventures. For items that have been identified as variable interests, or where there is involvement with an identified VIE, an in-depth review of the relationship between the relevant entities and NiSource is made to evaluate qualitative and quantitative factors to determine the primary beneficiary, if any, and whether additional disclosures would be required under the current standard. NIPSCO has a service agreement with Pure Air, a general partnership between Air Products and Chemicals, Inc. and First Air Partners LP, under which Pure Air provides scrubber services to reduce sulfur dioxide emissions for Units 7 and 8 at the Bailly Generating Station. NiSource has made an exhaustive effort to obtain information needed from Pure Air to determine the status of Pure Air as a VIE. However, NIPSCO has not been able to obtain this information and, as a result, it is unclear whether Pure Air is a VIE and if NIPSCO is the primary beneficiary. NIPSCO will continue to request the information required to determine whether Pure Air is a VIE. NIPSCO has no exposure to loss related to the service agreement with Pure Air. Payments under this agreement were $16.5 million and $17.0 million for the nine months ended September 30, 2015 and 2014 , respectively.

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2015
Debt Instrument [Line Items]
Long-term Debt [Text Block]	Prior to the Separation, CPG closed its placement of $2,750.0 million in aggregate principal amount of its senior notes. Using the proceeds from this offering, CPG made cash payments to NiSource representing the settlement of inter-company borrowings and the payment of a one-time special dividend. In May 2015, using proceeds from the cash payments from CPG, NiSource Finance settled its two bank term loans in the amount of $1,075.0 million and executed a tender offer for $750.0 million consisting of a combination of its 5.25% notes due 2017 , 6.40% notes due 2018 and 4.45% notes due 2021 . In conjunction with the debt retired, NiSource Finance recorded a $97.2 million loss on early extinguishment of long-term debt, primarily attributable to early redemption premiums.

Short-Term Borrowings

Short-Term Borrowings	9 Months Ended
	Sep. 30, 2015
Short-term Debt [Abstract]
Short-Term Borrowings	Short-Term Borrowings During the third quarter of 2015, NiSource Finance maintained a $1.5 billion revolving credit facility with a syndicate of banks led by Barclays Capital with a termination date of July 1, 2020 . The purpose of the facility is to fund ongoing working capital requirements including the provision of liquidity support for NiSource Finance's $1.5 billion commercial paper program, provide for issuance of letters of credit and also for general corporate purposes. At September 30, 2015 , NiSource had no outstanding borrowings under this facility. NiSource Finance's commercial paper program has a program limit of up to $1.5 billion with a dealer group comprised of Barclays, Citigroup, Credit Suisse and Wells Fargo. At September 30, 2015 , NiSource had no commercial paper outstanding. As of September 30, 2015 , NiSource had $14.7 million of stand-by letters of credit outstanding all of which were under the revolving credit facility. At December 31, 2014 , NiSource had $30.9 million of stand-by letters of credit outstanding of which $14.7 million were under the revolving credit facility. Transfers of accounts receivable are accounted for as secured borrowings resulting in the recognition of short-term borrowings on the Condensed Consolidated Balance Sheets (unaudited) in the amount of $107.2 million and $284.3 million as of September 30, 2015 and December 31, 2014 , respectively. Refer to Note 8, "Transfers of Financial Assets," for additional information. (in millions) September 30, December 31, Commercial Paper weighted average interest rate of 0.82% at December 31, 2014 $ — $ 792.6 Credit facilities borrowings weighted average interest rate of 1.44% at December 31, 2014 — 500.0 Accounts receivable securitization facility borrowings 107.2 284.3 Total Short-Term Borrowings $ 107.2 $ 1,576.9 Given their turnover is less than 90 days, cash flows related to the borrowings and repayments of the items listed above are presented net in the Condensed Statements of Consolidated Cash Flows (unaudited).

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2015
Share-based Compensation [Abstract]
Share-Based Compensation	Share-Based Compensation The NiSource stockholders originally approved and adopted the NiSource Inc. 2010 Omnibus Incentive Plan (“Omnibus Plan”) at the Annual Meeting of Stockholders held on May 11, 2010. Stockholders re-approved the Omnibus Plan as amended at the Annual Meeting of Stockholders held on May 12, 2015. The Omnibus Plan provides for awards to employees and non-employee directors of incentive and nonqualified stock options, stock appreciation rights, restricted stock, restricted stock units, performance shares, performance units, cash-based awards and other stock-based awards and supersedes the long-term incentive plan approved by stockholders on April 13, 1994 ("1994 Plan") and the Director Stock Incentive Plan ("Director Plan"). The Omnibus Plan provides that the number of shares of common stock of NiSource available for awards is 8,000,000 plus the number of shares subject to outstanding awards that expire or terminate for any reason that were granted under either the 1994 Plan or the Director Plan, plus the number of shares that were awarded as a result of the Separation-related adjustments described below. At September 30, 2015 , there were 5,705,683 shares reserved for future awards under the Omnibus Plan. NiSource recognized stock-based employee compensation expense of $4.2 million and $14.2 million for the three months ended September 30, 2015 and 2014 , respectively, as well as related tax benefits of $1.5 million and $5.5 million , respectively. For the nine months ended September 30, 2015 and 2014 , stock-based employee compensation expense of $15.1 million and $24.1 million was recognized, respectively, as well as related tax benefits of $5.4 million and $9.3 million , respectively. As of September 30, 2015 , the total remaining unrecognized compensation cost related to non-vested awards amounted to $15.8 million , which will be amortized over the weighted-average remaining requisite service period of 1.8 years . Restricted Stock Units and Restricted Stock. During the nine months ended September 30, 2015 , NiSource granted 660,230 restricted stock units and shares of restricted stock, subject to service conditions. The total grant date fair value of restricted stock units and shares of restricted stock was $23.9 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, which will be expensed, net of forfeitures, over the vesting period which is generally three years. As of September 30, 2015 , 967,191 non-vested (all of which are expected to vest) restricted stock units and shares of restricted stock were granted and outstanding. 401(k) Match, Profit Sharing and Company Contribution. NiSource has a voluntary 401(k) savings plan covering eligible employees that allows for periodic discretionary matches as a percentage of each participant’s contributions payable in shares of common stock. NiSource also has a retirement savings plan that provides for discretionary profit sharing contributions payable in shares of common stock to eligible employees based on earnings results; and eligible exempt employees hired after January 1, 2010, receive a non-elective company contribution of 3% of eligible pay payable in shares of NiSource common stock. For the quarters ended September 30, 2015 and 2014 , NiSource recognized 401(k) match, profit sharing and non-elective contribution expense of $4.8 million and $7.7 million , respectively. For the nine months ended September 30, 2015 and 2014, NiSource recognized 401(k) match, profit sharing and non-elective contribution expenses of $19.0 million and $20.3 million , respectively. Separation-related Adjustments. Pursuant to the terms of the Employee Matters Agreement, effective July 1, 2015, between NiSource and CPG, the Compensation Committee of the Board of Directors of NiSource Inc. approved an adjustment to outstanding awards granted under the Omnibus Plan in order to preserve the intrinsic aggregate value of such awards immediately before the Separation. The Separation-related adjustments did not have a material impact on either compensation expense or the potentially dilutive securities to be considered in the calculation of diluted earnings per share of common stock.

Other Commitments And Contingen

Other Commitments And Contingencies	9 Months Ended
	Sep. 30, 2015
Other Commitments and Contingencies [Abstract]
Commitments and Contingencies	Other Commitments and Contingencies A. Guarantees and Indemnities. As a part of normal business, NiSource 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 subsidiary on a stand-alone basis, thereby facilitating the extension of sufficient credit to accomplish the subsidiaries’ intended commercial purposes. The total guarantees and indemnities in existence at September 30, 2015 and the years in which they expire were: (in millions) Total 2015 2016 2017 2018 2019 After Guarantees of subsidiaries debt $ 6,135.5 $ 230.0 $ 291.5 $ 267.4 $ 476.0 $ 500.0 $ 4,370.6 Accounts receivable securitization 107.2 107.2 — — — — — Letters of credit 14.7 — 14.7 — — — — Other guarantees 54.9 — — — — 1.7 53.2 Total commercial commitments $ 6,312.3 $ 337.2 $ 306.2 $ 267.4 $ 476.0 $ 501.7 $ 4,423.8 Guarantees of Subsidiaries Debt. NiSource has guaranteed the payment of $6,135.5 million of debt for various wholly-owned subsidiaries including NiSource Finance and Columbia of Massachusetts, and through a support agreement for Capital Markets, which is reflected on NiSource’s Condensed Consolidated Balance Sheets (unaudited). The subsidiaries are required to comply with certain covenants under the debt indenture and in the event of default, NiSource would be obligated to pay the debt’s principal and related interest. NiSource does not anticipate its subsidiaries will have any difficulty maintaining compliance. On October 3, 2011, NiSource executed a Second Supplemental Indenture to the original Columbia of Massachusetts Indenture dated April 1, 1991, for the specific purpose of guaranteeing Columbia of Massachusetts’ outstanding unregistered medium-term notes. Lines and Letters of Credit and Accounts Receivable Advances. During the third quarter of 2015, NiSource Finance maintained a $1.5 billion revolving credit facility with a syndicate of banks led by Barclays Capital with a termination date of July 1, 2020 . The purpose of the facility is to fund ongoing working capital requirements including the provision of liquidity support for NiSource’s $1.5 billion commercial paper program, provide for issuance of letters of credit, and also for general corporate purposes. At September 30, 2015 , NiSource had no borrowings under its five-year revolving credit facility, no commercial paper outstanding and $107.2 million outstanding under its accounts receivable securitization agreements. At September 30, 2015 , NiSource had issued stand-by letters of credit of approximately $14.7 million for the benefit of third parties. See Note 14, "Short-Term Borrowings," for additional information. B. Legal Proceedings. The Company is party to certain claims and legal proceedings arising in the ordinary course of business, none of which is deemed to be individually material at this time. Due to the inherent uncertainty of litigation, there can be no assurance that the resolution of any particular claim or proceeding would not have a material adverse effect on the Company’s results of operations, financial position or liquidity. It is possible that if one or more of such matters were decided against the Company, the effects could be material to the Company’s results of operations in the period in which the Company would be required to record or adjust the related liability and could also be material to the Company’s cash flows in the periods the Company would be required to pay such liability. C. Environmental Matters. NiSource operations are subject to environmental statutes and regulations related to air quality, water quality, hazardous waste and solid waste. NiSource believes that it is in substantial compliance with those environmental regulations currently applicable to its operations. It is management'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 fines and penalties will not be incurred. Management expects a significant portion of environmental assessment and remediation costs to be recoverable through rates for certain NiSource companies. As of September 30, 2015 and December 31, 2014 , NiSource had recorded an accrual of approximately $125.4 million and $126.6 million , respectively, to cover environmental remediation at various sites. The current portion of this accrual is included in "Legal and environmental" in the Condensed Consolidated Balance Sheets (unaudited). The noncurrent portion is included in "Other noncurrent liabilities" in the Condensed Consolidated Balance Sheets (unaudited). NiSource 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 may 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. These expenditures are not currently estimable at some sites. NiSource periodically adjusts its accrual as information is collected and estimates become more refined. Air The actions listed below could require further reductions in emissions from various emission sources. NiSource will continue to closely monitor developments in these matters. Climate Change. Future legislative and regulatory programs could significantly restrict emissions of GHGs or could impose a cost or tax on GHG emissions. National Ambient Air Quality Standards. The CAA requires the EPA to set NAAQS for particulate matter and five other pollutants considered harmful to public health and the environment. Periodically, the EPA imposes new or modifies existing NAAQS. States that contain areas that do not meet the new or revised standards must take steps to maintain or achieve compliance with the standards. These steps could include additional pollution controls on boilers, engines, turbines and other facilities owned by electric generation and gas distribution operations. The following NAAQS were recently added or modified: Ozone: On October 1, 2015, the EPA issued a pre-publication final rule to lower the 8-hour ozone standard from 75 ppb to 70 ppb. After the EPA proceeds with designations, areas where NiSource operates that are currently designated as attainment may be re-classified as non-attainment. NiSource will continue to monitor this matter and cannot estimate its impact at this time. Waste NiSource subsidiaries are potentially responsible parties at waste disposal sites under the CERCLA (commonly known as Superfund) and similar state laws. Additionally, NiSource affiliates have retained environmental liabilities, including cleanup liabilities, associated with certain former operations. A program has been instituted to identify and investigate former MGP sites where Gas Distribution Operations subsidiaries or predecessors may have liability. The program has identified 64 such sites where liability is probable. Remedial actions at many of these sites are being overseen by state or federal environmental agencies through consent agreements or voluntary remediation agreements. NiSource utilizes a probabilistic model to estimate its future remediation costs related to its MGP sites. The model was prepared with the assistance of a third-party and incorporates NiSource and general industry experience with remediating MGP sites. NiSource completes an annual refresh of the model in the second quarter of each fiscal year. No material changes to the estimated future remediation costs were noted as a result of the refresh completed as of June 30, 2015. The total estimated liability at NiSource related to the facilities subject to remediation was $112.6 million and $121.5 million at September 30, 2015 and December 31, 2014 , respectively. The liability represents NiSource’s best estimate of the probable cost to remediate the facilities. NiSource believes that it is reasonably possible that remediation costs could vary by as much as $25 million in addition to the costs noted above. Remediation costs are estimated based on the best available information, applicable remediation standards at the balance sheet date, and experience with similar facilities. Additional Issues Related to Individual Business Segments The sections below describe various regulatory actions that affect individual business segments for which NiSource has retained a liability. Electric Operations. Air NIPSCO is subject to a number of air-quality mandates in the next several years. The mandates, which include the NSR Consent Decree, the Utility Mercury and Air Toxics Standards Rule (MATS), and the Clean Power Plan (CPP), require or may require NIPSCO to make capital improvements to its electric generating stations. The cost of capital improvements associated with the NSR Consent Decree and MATS is estimated to be $860 million , of which approximately $41.8 million remains to be spent. The cost to comply with the CPP cannot be estimated at this time. NIPSCO believes that the capital costs are probable of recovery from customers. Utility Mercury and Air Toxics Standards Rule: On December 16, 2011, the EPA finalized the MATS rule establishing new emissions limits for mercury and other air toxics. NIPSCO’s affected units have completed projects to meet the April 2015 compliance deadline. For NIPSCO’s remaining affected units, a one-year compliance extension granted by IDEM delays the compliance date until April 2016. NIPSCO continues to implement an IURC-approved plan for the installation of additional environmental controls needed to comply with the MATS extension. On June 29, 2015, the United States Supreme Court remanded the MATS rule back to the United States Court of Appeals for the District of Columbia Circuit for further proceedings. The MATS rule remains in effect until the Court of Appeals issues a ruling. The timing for resolving the process is unclear at this time. NIPSCO will continue to monitor developments in this matter. Clean Power Plan : On October 23, 2015, the EPA issued a final rule to regulate CO2 emissions from existing fossil-fuel EGUs under section 111(d) of the CAA. The final rule establishes national CO2 emission rate standards that are applied to each state’s mix of affected EGUs to establish a state-specific emission rate and mass emission limits. The final rule requires each state to submit a plan indicating how the state will meet the EPA's emission rate or mass emission limit, including possibly imposing reduction obligations on specific units. Initial state plans are required to be submitted to the EPA by September 6, 2016. As part of the initial submittal of state plans, states have the option to request extensions for the submittal of final state plans. If granted an extension by the EPA, a state’s final plan must be submitted by September 6, 2018. If a state does not submit a satisfactory plan, the EPA will impose a FIP on that state. A proposed FIP was issued on August 3, 2015, concurrent with the pre-publication final rule. The cost to comply with this rule will depend on a number of factors, including the requirements of the state plan or final FIP and the level of NIPSCO's required CO2 emission reductions. It is possible that this new rule, comprehensive federal or state GHG legislation, or other GHG regulation could result in additional expense or compliance costs that could materially impact NiSource's financial results. NIPSCO will continue to monitor this matter and cannot estimate its impact at this time. Water On August 15, 2014, the EPA published the final Phase II Rule of the Clean Water Act Section 316(b), which requires all large existing steam electric generating stations to meet certain performance standards to reduce the effects on aquatic organisms at their cooling water intake structures. Under this rule, stations will have to either demonstrate that the performance of their existing fish protection systems meet the new standards or develop new systems, such as a closed-cycle cooling tower. The cost to comply will depend on a number of factors, including evaluation of the various compliance options available under the regulation and permitting-related determinations by IDEM. NIPSCO estimates that the cost of compliance is between $4 million and $35 million , dependent upon study results, agency requirements and technology ultimately required to achieve compliance. On September 30, 2015, the EPA issued a pre-publication final rule to amend the effluent limitations guidelines and standards for the Steam Electric Power Generating category. Once in effect, this rule will impose new water treatment requirements on NIPSCO’s electric generating facilities. A final rule is expected in the fourth quarter of 2015. NIPSCO is currently reviewing the rule and cannot estimate the cost of compliance at this time. Waste On April 17, 2015, the EPA released a final rule for regulation of CCRs. The rule regulates CCRs under the Resource Conservation and Recovery Act Subtitle D, which determines them to be non-hazardous. The rule will require increased groundwater monitoring, reporting, recordkeeping and posting related information to the Internet. The rule also establishes requirements related to CCR management, impoundments, landfills and storage. The rule will allow NIPSCO to continue its byproduct beneficial use program. The publication of the CCR rule resulted in revisions to previously recorded legal obligations associated with the retirement of certain NIPSCO facilities. The actual asset retirement costs related to the CCR rule may vary substantially from the estimates used to record the increased asset retirement obligation due to the uncertainty about the compliance strategies that will be used and the preliminary nature of available data used to estimate costs. Refer to Note 5, "Asset Retirement Obligations," for further information. In addition, in order to comply with the rule NIPSCO will be required to incur future capital expenditures to modify its infrastructure and manage CCRs. As allowed by the EPA, NIPSCO will continue to collect data over time to determine the nature, extent and cost of these future capital expenditures. Given the preliminary stage of this data collection, NIPSCO is unable to estimate a range for these future capital expenditures at this time. D. Other Matters. Transmission Upgrade Agreements. On February 11, 2014, NIPSCO entered into two TUAs with upgrade sponsors to complete upgrades on NIPSCO’s transmission system on behalf of those sponsors. The upgrade sponsors agreed to reimburse NIPSCO for the total cost to construct transmission upgrades and place them into service, multiplied by a rate of 1.71 ("the multiplier"). On June 10, 2014, certain upgrade sponsors for both TUAs filed a complaint at the FERC against NIPSCO regarding the multiplier stated in the TUAs. On June 30, 2014, NIPSCO filed an answer defending the terms of the TUAs and the just and reasonable nature of the multiplier charged therein and moved for dismissal of the complaint. On December 8, 2014, the FERC issued an order in response to the complaint finding that it is appropriate for NIPSCO to recover, through the multiplier, substantiated costs of ownership related to the TUAs. The FERC set for hearing the issue of what constitutes the incremental costs NIPSCO will incur, but is holding that hearing in abeyance to allow for settlement. NIPSCO will continue to monitor developments in this matter and does not believe the impact is material to the Condensed Consolidated Financial Statements (unaudited). Springfield, Massachusetts. On November 23, 2012, while Columbia of Massachusetts was investigating the source of an odor of gas at a service location in Springfield, Massachusetts, a gas service line was pierced and an explosion occurred. While this explosion impacted multiple buildings and resulted in several injuries, no life threatening injuries or fatalities have been reported. Columbia of Massachusetts fully cooperated with both the Massachusetts DPU and the Occupational Safety & Health Administration in their investigations of this incident, which have been concluded. Columbia of Massachusetts believes any costs associated with damages, injuries and other losses related to this incident are substantially covered by insurance. Any amounts not covered by insurance are not expected to have a material impact on NiSource's consolidated financial statements. In accordance with GAAP, NiSource recorded any accruals and the related insurance recoveries resulting from this incident on a gross basis within the Condensed Consolidated Balance Sheets (unaudited).

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 30, 2015
Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The following tables display the components of Accumulated Other Comprehensive Loss for the three and nine months ended September 30, 2015 and 2014 : Three Months Ended September 30, 2015 (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of July 1, 2015 $ — $ (20.0 ) $ (24.4 ) $ (44.4 ) Other comprehensive income before reclassifications 0.5 (0.2 ) (1.3 ) (1.0 ) Amounts reclassified from accumulated other comprehensive income (0.2 ) 0.4 1.1 1.3 Net current-period other comprehensive income (loss) 0.3 0.2 (0.2 ) 0.3 Distribution of CPG to shareholders (Note 4) — 13.9 10.6 24.5 Balance as of September 30, 2015 $ 0.3 $ (5.9 ) $ (14.0 ) $ (19.6 ) Nine Months Ended September 30, 2015 (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of January 1, 2015 $ 0.3 $ (23.6 ) $ (27.3 ) $ (50.6 ) Other comprehensive income before reclassifications 0.3 (0.2 ) 1.2 1.3 Amounts reclassified from accumulated other comprehensive income (0.3 ) 2.0 1.5 3.2 Net current-period other comprehensive income — 1.8 2.7 4.5 Allocation of AOCI to noncontrolling interest — 2.0 — 2.0 Distribution of CPG to shareholders (Note 4) — 13.9 10.6 24.5 Balance as of September 30, 2015 $ 0.3 $ (5.9 ) $ (14.0 ) $ (19.6 ) Three Months Ended September 30, 2014 (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated (1) Balance as of July 1, 2014 $ 0.5 $ (24.5 ) $ (17.4 ) $ (41.4 ) Other comprehensive income before reclassifications (0.5 ) — (0.1 ) (0.6 ) Amounts reclassified from accumulated other comprehensive income (0.1 ) 0.6 (0.1 ) 0.4 Net current-period other comprehensive (loss) income (0.6 ) 0.6 (0.2 ) (0.2 ) Balance as of September 30, 2014 $ (0.1 ) $ (23.9 ) $ (17.6 ) $ (41.6 ) Nine Months Ended September 30, 2014 (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of January 1, 2014 $ (0.3 ) $ (25.8 ) $ (17.5 ) $ (43.6 ) Other comprehensive income before reclassifications 0.5 0.1 (0.4 ) 0.2 Amounts reclassified from accumulated other comprehensive income (0.3 ) 1.8 0.3 1.8 Net current-period other comprehensive income (loss) 0.2 1.9 (0.1 ) 2.0 Balance as of September 30, 2014 $ (0.1 ) $ (23.9 ) $ (17.6 ) $ (41.6 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits.

Business Segment Information

Business Segment Information	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Business Segment Information	Business Segment Information On July 1, 2015, NiSource completed the Separation. CPG's operations consisted of all of NiSource's Columbia Pipeline Group Operations segment prior to the Separation. Results of the Columbia Pipeline Group Operations segment are included in discontinued operations. At September 30, 2015 , NiSource’s operations are divided into two primary business segments. The Gas Distribution Operations segment provides natural gas service and transportation for residential, commercial and industrial customers in Ohio, Pennsylvania, Virginia, Kentucky, Maryland, Indiana and Massachusetts. The Electric Operations segment provides electric service in 20 counties in the northern part of Indiana. The following table provides information about business segments. NiSource uses operating income as its primary measurement for each of the reported segments and makes decisions on finance, dividends and taxes at the corporate level on a consolidated basis. Segment revenues include intersegment sales to affiliated subsidiaries, which are eliminated in consolidation. Affiliated sales are recognized on the basis of prevailing market, regulated prices or at levels provided for under contractual agreements. Operating income is derived from revenues and expenses directly associated with each segment. Three Months Ended Nine Months Ended September 30, (in millions) 2015 2014 2015 2014 Revenues Gas Distribution Operations Unaffiliated $ 384.6 $ 411.9 $ 2,349.3 $ 2,593.9 Intersegment 0.1 — 0.4 0.2 Total 384.7 411.9 2,349.7 2,594.1 Electric Operations Unaffiliated 428.4 424.4 1,199.5 1,279.9 Intersegment 0.2 0.3 0.6 0.6 Total 428.6 424.7 1,200.1 1,280.5 Corporate and Other Unaffiliated 4.2 1.9 5.2 5.3 Intersegment 94.1 105.9 288.1 303.6 Total 98.3 107.8 293.3 308.9 Eliminations (94.4 ) (106.2 ) (289.1 ) (304.4 ) Consolidated Gross Revenues $ 817.2 $ 838.2 $ 3,554.0 $ 3,879.1 Operating Income (Loss) Gas Distribution Operations $ 20.0 $ 0.8 $ 394.9 $ 362.4 Electric Operations 98.5 76.9 214.2 218.7 Corporate and Other (8.8 ) (6.6 ) (28.7 ) (18.9 ) Consolidated Operating Income $ 109.7 $ 71.1 $ 580.4 $ 562.2

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	9 Months Ended
	Sep. 30, 2015
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information The following table provides additional information regarding NiSource’s Condensed Statements of Consolidated Cash Flows (unaudited) for the nine months ended September 30, 2015 and 2014 : Nine Months Ended September 30, (in millions) 2015 2014 Supplemental Disclosures of Cash Flow Information Non-cash transactions: Capital expenditures included in current liabilities $ 130.7 $ 117.6 Assets acquired under a capital lease 5.5 69.9 Schedule of interest and income taxes paid: Cash paid for interest, net of interest capitalized $ 354.1 $ 375.0 Cash paid for income taxes 20.2 12.2

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2015
Earnings Per Share [Abstract]
Computation Of Diluted Average Common Shares	Three Months Ended Nine Months Ended September 30, September 30, (in thousands) 2015 2015 2014 Denominator Basic average common shares outstanding 318,090 317,390 314,889 Dilutive potential common shares: Stock options — — 30 Shares contingently issuable under employee stock plans — — 649 Shares restricted under stock plans (1) 3,375 3,328 438 Diluted Average Common Shares 321,465 320,718 316,006

Discontinued Operations (Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 30, 2015
Components of Net Income (Loss), Current Year [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations [Table Text Block]	Three Months Ended Nine Months Ended September 30, 2015 September 30, 2015 (in millions) Columbia Pipeline Group Operations Corporate and Other Total Columbia Pipeline Group Operations Corporate and Other Total Net Revenues Transportation and storage revenues $ — $ — $ — $ 561.4 $ — $ 561.4 Other revenues — — — 94.3 — 94.3 Total Sales Revenues — — — 655.7 — 655.7 Less: Cost of sales (excluding depreciation and amortization) — — — 0.2 — 0.2 Net Revenues — — — 655.5 — 655.5 Operating Expenses Operation and maintenance 5.5 (1) — 5.5 374.8 (1) — 374.8 Depreciation and amortization — — — 66.4 — 66.4 Gain on sale of assets — — — (13.6 ) — (13.6 ) Other taxes — — — 38.0 — 38.0 Total Operating Expenses 5.5 — 5.5 465.6 — 465.6 Equity Earnings in Unconsolidated Affiliates — — — 29.1 — 29.1 Operating (Loss) Income from discontinued operations (5.5 ) — (5.5 ) 219.0 — 219.0 Other Income (Deductions) Interest expense, net — — — (37.1 ) — (37.1 ) Other, net — — — 7.8 (0.6 ) 7.2 Total Other Deductions — — — (29.3 ) (0.6 ) (29.9 ) (Loss) Income from Discontinued Operations before Income Taxes (5.5 ) — (5.5 ) 189.7 (0.6 ) 189.1 Income Taxes 14.2 (2) — 14.2 80.9 (0.3 ) 80.6 (Loss) Income from Discontinued Operations - net of taxes $ (19.7 ) $ — $ (19.7 ) $ 108.8 $ (0.3 ) $ 108.5
Components of Net Income (Loss), Prior Year [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations [Table Text Block]	Three Months Ended Nine Months Ended September 30, 2014 September 30, 2014 (in millions) Columbia Pipeline Group Operations Corporate and Other Total Columbia Pipeline Group Operations Corporate and Other Total Net Revenues Transportation and storage revenues $ 243.1 $ — $ 243.1 $ 746.1 $ — $ 746.1 Other revenues 74.5 — 74.5 260.6 — 260.6 Total Sales Revenues 317.6 — 317.6 1,006.7 — 1,006.7 Less: Cost of sales (excluding depreciation and amortization) — — — 0.2 — 0.2 Net Revenues 317.6 — 317.6 1,006.5 — 1,006.5 Operating Expenses Operation and maintenance 202.1 (1) — 202.1 573.3 (1) — 573.3 Depreciation and amortization 29.2 — 29.2 87.7 — 87.7 Gain on sale of assets (3.0 ) — (3.0 ) (20.8 ) — (20.8 ) Other taxes 14.6 — 14.6 50.3 — 50.3 Total Operating Expenses 242.9 — 242.9 690.5 — 690.5 Equity Earnings in Unconsolidated Affiliates 12.0 — 12.0 32.9 — 32.9 Operating Income from discontinued operations 86.7 — 86.7 348.9 — 348.9 Other Income (Deductions) Interest expense, net (14.9 ) — (14.9 ) (40.4 ) — (40.4 ) Other, net 3.5 (0.2 ) 3.3 7.8 (1.0 ) 6.8 Total Other Deductions (11.4 ) (0.2 ) (11.6 ) (32.6 ) (1.0 ) (33.6 ) Income (Loss) from Discontinued Operations before Income Taxes 75.3 (0.2 ) 75.1 316.3 (1.0 ) 315.3 Income Taxes 26.6 (0.1 ) 26.5 116.6 (0.4 ) 116.2 Income (Loss) from Discontinued Operations - net of taxes $ 48.7 $ (0.1 ) $ 48.6 $ 199.7 $ (0.6 ) $ 199.1
Carrying Value of Assets [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations [Table Text Block]	December 31, 2014 (in millions) Columbia Pipeline Group Operations Current Assets Cash and cash equivalents $ 0.5 Accounts receivable, net 149.3 Gas inventory 4.8 Materials and supplies, at average cost 24.9 Exchange gas receivable 34.8 Regulatory assets 6.1 Deferred income taxes 57.9 Prepayments and other 63.0 Total current assets $ 341.3 Noncurrent Assets Net property, plant and equipment $ 4,959.7 Goodwill 1,975.5 Unconsolidated affiliates 444.3 Other investments 5.6 Regulatory assets 151.9 Deferred charges and other 9.0 Total noncurrent assets $ 7,546.0
Carrying Value of Liabilities [Domain]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations [Table Text Block]	December 31, 2014 (in millions) Columbia Pipeline Group Operations Current Liabilities Accounts payable $ 60.5 Customer deposits and credits 13.4 Taxes accrued 106.9 Exchange gas payable 34.7 Deferred revenue 22.2 Regulatory liabilities 1.3 Accrued liability for postretirement and postemployment benefits 0.6 Legal and environmental 1.5 Accrued capital expenditures 61.1 Other accruals 66.8 Total current liabilities $ 369.0 Noncurrent Liabilities Deferred income taxes $ 1,272.2 Deferred investment tax credits 0.2 Deferred credits 0.2 Accrued liability for postretirement and postemployment benefits (1) (58.0 ) Regulatory liabilities 294.2 Asset retirement obligations 23.2 Other noncurrent liabilities 84.3 Total noncurrent liabilities $ 1,616.3

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	9 Months Ended
	Sep. 30, 2015
Asset Retirement Obligation [Abstract]
Changes In Company's Liability For Asset Retirement Obligations	(in millions) 2015 2014 Balance as of January 1, $ 136.2 $ 148.1 Accretion recorded as a regulatory asset/liability 5.9 6.3 Additions 6.4 0.3 Settlements (4.3 ) (1.3 ) Change in estimated cash flows (1) 37.0 (7.4 ) Balance as of September 30, $ 181.2 $ 146.0 (1) The current year change in estimated cash flows is primarily attributable to estimated costs associated with the EPA's final rule for regulation of CCRs and changes to cost estimates for certain solid waste management units. See Note 16, "Other Commitments and Contingencies," for additional information on CCRs.

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	Recurring Fair Value Measurements September 30, 2015 (in millions) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Balance as of September 30, 2015 Assets Price risk management assets: Commodity financial price risk programs $ 0.1 $ — $ — $ 0.1 Available-for-sale securities 34.0 101.4 — 135.4 Total $ 34.1 $ 101.4 $ — $ 135.5 Liabilities Price risk management liabilities: Commodity financial price risk programs $ 16.3 $ — $ 0.6 $ 16.9 Total $ 16.3 $ — $ 0.6 $ 16.9 Recurring Fair Value Measurements (in millions) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Balance as of December 31, 2014 Assets Price risk management assets: Commodity financial price risk programs $ 0.1 $ — $ — $ 0.1 Available-for-sale securities 28.4 103.5 — 131.9 Total $ 28.5 $ 103.5 $ — $ 132.0 Liabilities Price risk management liabilities: Commodity financial price risk programs $ 14.2 $ — $ 0.1 $ 14.3 Total $ 14.2 $ — $ 0.1 $ 14.3
Available-For-Sale Debt Securities	September 30, 2015 (in millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale debt securities U.S. Treasury securities $ 33.8 $ 0.3 $ — $ 34.1 Corporate/Other bonds 101.0 0.7 (0.4 ) 101.3 Total Available-for-sale debt securities $ 134.8 $ 1.0 $ (0.4 ) $ 135.4 December 31, 2014 (in millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale debt securities U.S. Treasury securities $ 30.8 $ 0.3 $ (0.2 ) $ 30.9 Corporate/Other bonds 100.6 1.0 (0.6 ) 101.0 Total Available-for-sale debt securities $ 131.4 $ 1.3 $ (0.8 ) $ 131.9
Carrying Amount And Estimated Fair Values Of Financial Instruments	(in millions) Carrying Amount as of September 30, 2015 Estimated Fair Value as of September 30, 2015 Carrying Amount as of Dec. 31, 2014 Estimated Fair Value as of Dec. 31, 2014 Long-term debt (including current portion) $ 6,576.1 $ 7,286.7 $ 8,422.5 $ 9,505.7

Transfers Of Financial Assets (

Transfers Of Financial Assets (Tables)	9 Months Ended
	Sep. 30, 2015
Transfers and Servicing [Abstract]
Schedule Of Gross And Net Receivables Transferred As Well As Short-Term Borrowings Related To The Securitization Transactions	(in millions) September 30, 2015 December 31, 2014 Gross Receivables $ 347.9 $ 611.7 Less: Receivables not transferred 240.7 327.4 Net receivables transferred $ 107.2 $ 284.3 Short-term debt due to asset securitization $ 107.2 $ 284.3

Goodwill (Tables)

Goodwill (Tables)	9 Months Ended
	Sep. 30, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	(in millions) Gas Distribution Operations Electric Operations Corporate and Other Total Goodwill $ 1,690.7 $ — $ — $ 1,690.7

Pension And Other Postretirem35

Pension And Other Postretirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Components Of The Plans' Net Periodic Benefits Cost	Pension Benefits Other Postretirement Benefits Three Months Ended September 30, (in millions) 2015 2014 2015 2014 Components of Net Periodic Benefit Cost Service cost $ 7.9 $ 7.5 $ 1.4 $ 1.7 Interest cost 22.8 23.8 6.2 5.9 Expected return on assets (37.3 ) (39.3 ) (5.6 ) (5.1 ) Amortization of prior service cost (credit) 0.1 0.3 (1.1 ) (1.4 ) Recognized actuarial loss 13.8 10.2 0.7 0.2 Total Net Periodic Benefit Cost $ 7.3 $ 2.5 $ 1.6 $ 1.3 Pension Benefits Other Postretirement Benefits Nine Months Ended September 30, (in millions) 2015 2014 2015 2014 Components of Net Periodic Benefit Cost Service cost $ 24.3 $ 22.5 $ 4.5 $ 5.7 Interest cost 67.0 71.4 17.8 19.5 Expected return on assets (117.7 ) (117.9 ) (15.6 ) (15.1 ) Amortization of prior service cost (credit) 0.3 0.9 (3.9 ) (2.9 ) Recognized actuarial loss 41.6 30.6 2.8 0.2 Total Net Periodic Benefit Cost $ 15.5 $ 7.5 $ 5.6 $ 7.4
Schedule of Assumptions Used [Table Text Block]	Pension Benefits Other Postretirement Benefits July 1, 2015 December 31, 2014 July 1, 2015 December 31, 2014 Actuarial Assumptions Discount Rate 4.19 % 3.81 % 4.31 % 3.94 % Expected return on assets 8.30 % 8.30 % 8.15 % 8.14 % Health Care Trend Rates Trend for 2015 — — 8.76 % 6.90 % Ultimate Trend — — 4.50 % 4.50 % Year Ultimate Trend Reached — — 2022 2021

Short-Term Borrowings (Tables)

Short-Term Borrowings (Tables)	9 Months Ended
	Sep. 30, 2015
Short-term Debt [Abstract]
Schedule Of Short-Term Borrowings	(in millions) September 30, December 31, Commercial Paper weighted average interest rate of 0.82% at December 31, 2014 $ — $ 792.6 Credit facilities borrowings weighted average interest rate of 1.44% at December 31, 2014 — 500.0 Accounts receivable securitization facility borrowings 107.2 284.3 Total Short-Term Borrowings $ 107.2 $ 1,576.9

Other Commitments And Conting37

Other Commitments And Contingencies (Tables)	9 Months Ended
	Sep. 30, 2015
Other Commitments and Contingencies [Abstract]
Schedule of Guarantor Obligations	The total guarantees and indemnities in existence at September 30, 2015 and the years in which they expire were: (in millions) Total 2015 2016 2017 2018 2019 After Guarantees of subsidiaries debt $ 6,135.5 $ 230.0 $ 291.5 $ 267.4 $ 476.0 $ 500.0 $ 4,370.6 Accounts receivable securitization 107.2 107.2 — — — — — Letters of credit 14.7 — 14.7 — — — — Other guarantees 54.9 — — — — 1.7 53.2 Total commercial commitments $ 6,312.3 $ 337.2 $ 306.2 $ 267.4 $ 476.0 $ 501.7 $ 4,423.8

Accumulated Other Comprehensi38

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 30, 2015
Other Comprehensive Income (Loss), Tax [Abstract]
Components Of Accumulated Other Comprehensive Loss	Three Months Ended September 30, 2015 (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of July 1, 2015 $ — $ (20.0 ) $ (24.4 ) $ (44.4 ) Other comprehensive income before reclassifications 0.5 (0.2 ) (1.3 ) (1.0 ) Amounts reclassified from accumulated other comprehensive income (0.2 ) 0.4 1.1 1.3 Net current-period other comprehensive income (loss) 0.3 0.2 (0.2 ) 0.3 Distribution of CPG to shareholders (Note 4) — 13.9 10.6 24.5 Balance as of September 30, 2015 $ 0.3 $ (5.9 ) $ (14.0 ) $ (19.6 ) Nine Months Ended September 30, 2015 (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of January 1, 2015 $ 0.3 $ (23.6 ) $ (27.3 ) $ (50.6 ) Other comprehensive income before reclassifications 0.3 (0.2 ) 1.2 1.3 Amounts reclassified from accumulated other comprehensive income (0.3 ) 2.0 1.5 3.2 Net current-period other comprehensive income — 1.8 2.7 4.5 Allocation of AOCI to noncontrolling interest — 2.0 — 2.0 Distribution of CPG to shareholders (Note 4) — 13.9 10.6 24.5 Balance as of September 30, 2015 $ 0.3 $ (5.9 ) $ (14.0 ) $ (19.6 ) Three Months Ended September 30, 2014 (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated (1) Balance as of July 1, 2014 $ 0.5 $ (24.5 ) $ (17.4 ) $ (41.4 ) Other comprehensive income before reclassifications (0.5 ) — (0.1 ) (0.6 ) Amounts reclassified from accumulated other comprehensive income (0.1 ) 0.6 (0.1 ) 0.4 Net current-period other comprehensive (loss) income (0.6 ) 0.6 (0.2 ) (0.2 ) Balance as of September 30, 2014 $ (0.1 ) $ (23.9 ) $ (17.6 ) $ (41.6 ) Nine Months Ended September 30, 2014 (in millions) Gains and Losses on Securities (1) Gains and Losses on Cash Flow Hedges (1) Pension and OPEB Items (1) Accumulated Other Comprehensive Loss (1) Balance as of January 1, 2014 $ (0.3 ) $ (25.8 ) $ (17.5 ) $ (43.6 ) Other comprehensive income before reclassifications 0.5 0.1 (0.4 ) 0.2 Amounts reclassified from accumulated other comprehensive income (0.3 ) 1.8 0.3 1.8 Net current-period other comprehensive income (loss) 0.2 1.9 (0.1 ) 2.0 Balance as of September 30, 2014 $ (0.1 ) $ (23.9 ) $ (17.6 ) $ (41.6 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits.

Business Segment Information (T

Business Segment Information (Tables)	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Schedule Of Operating Income Derived From Revenues And Expenses By Segment	Three Months Ended Nine Months Ended September 30, (in millions) 2015 2014 2015 2014 Revenues Gas Distribution Operations Unaffiliated $ 384.6 $ 411.9 $ 2,349.3 $ 2,593.9 Intersegment 0.1 — 0.4 0.2 Total 384.7 411.9 2,349.7 2,594.1 Electric Operations Unaffiliated 428.4 424.4 1,199.5 1,279.9 Intersegment 0.2 0.3 0.6 0.6 Total 428.6 424.7 1,200.1 1,280.5 Corporate and Other Unaffiliated 4.2 1.9 5.2 5.3 Intersegment 94.1 105.9 288.1 303.6 Total 98.3 107.8 293.3 308.9 Eliminations (94.4 ) (106.2 ) (289.1 ) (304.4 ) Consolidated Gross Revenues $ 817.2 $ 838.2 $ 3,554.0 $ 3,879.1 Operating Income (Loss) Gas Distribution Operations $ 20.0 $ 0.8 $ 394.9 $ 362.4 Electric Operations 98.5 76.9 214.2 218.7 Corporate and Other (8.8 ) (6.6 ) (28.7 ) (18.9 ) Consolidated Operating Income $ 109.7 $ 71.1 $ 580.4 $ 562.2

Supplemental Cash Flow Inform40

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2015
Supplemental Cash Flow Information [Abstract]
Additional Information Regarding Condensed Statements Of Consolidated Cash Flows	Nine Months Ended September 30, (in millions) 2015 2014 Supplemental Disclosures of Cash Flow Information Non-cash transactions: Capital expenditures included in current liabilities $ 130.7 $ 117.6 Assets acquired under a capital lease 5.5 69.9 Schedule of interest and income taxes paid: Cash paid for interest, net of interest capitalized $ 354.1 $ 375.0 Cash paid for income taxes 20.2 12.2

Earnings Per Share Table (Detai

Earnings Per Share Table (Details) - shares shares in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Basic Average Common Shares Outstanding		318,090	315,418	317,390	314,889
Stock options		0		0	30
Shares contingently issuable under employee stock plans		0		0	649
Shares restricted under stock plans	[1]	3,375		3,328	438
Weighted Average Number of Shares Outstanding, Diluted		321,465	315,418	320,718	316,006
[1]	Change due to Separation-related adjustments, see Note 15, "Share-Based Compensation."

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jul. 01, 2015	May. 22, 2015	Dec. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets	$ 17,055.9		$ 17,055.9				$ 24,866.3
Transaction Costs Related to Separation	5.5	$ 9.3	54.4	$ 12.8
Columbia Pipeline Group Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets	0		0		$ 9,200
Liabilities	0		0		5,600
Equity					$ 3,600
Columbia Pipeline Group [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Related Party Transaction, Other Revenues from Transactions with Related Party	$ 31.6	$ 31.9	$ 105.4	$ 106.3
Senior Notes [Member] | Columbia Pipeline Group [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Debt Instrument, Face Amount						$ 2,750

Discontinued Operations (Income

Discontinued Operations (Income Statement Disclosures) (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Natural Gas Midstream Revenue	$ 0		$ 243.1		$ 561.4		$ 746.1
Disposal Group, Including Discontinued Operation, Other Revenue, Net	0		74.5		94.3		260.6
Disposal Group, Including Discontinued Operation, Revenue	0		317.6		655.7		1,006.7
Disposal Group, Including Discontinued Operation, Costs of Goods Sold	0		0		0.2		0.2
Disposal Group, Including Discontinued Operation, Gross Profit (Loss)	0		317.6		655.5		1,006.5
Disposal Group, Including Discontinued Operation, Utilities Operating Expense, Maintenance and Operations	5.5		202.1		374.8		573.3
Disposal Group, Including Discontinued Operation, Depreciation and Amortization	0		29.2		66.4		87.7
Disposal Group, Including Discontinued Operation, Impairment And Gain Loss On Sale Of Assets, Net	0		(3)		(13.6)		(20.8)
Disposal Group, Including Discontinued Operation, Taxes, Miscellaneous	0		14.6		38		50.3
Disposal Group, Including Discontinued Operation, Operating Expense	5.5		242.9		465.6		690.5
Disposal Group, Including Discontinued Operation, Income Loss From Equity Method Investments	0		12		29.1		32.9
Disposal Group, Including Discontinued Operation, Operating Income (Loss)	(5.5)		86.7		219		348.9
Disposal Group, Including Discontinued Operation, Interest Expense	0		(14.9)		(37.1)		(40.4)
Disposal Group, Including Discontinued Operation, Other Expense	0		3.3		7.2		6.8
Disposal Group, Including Discontinued Operation, Nonoperating Income Expense	0		(11.6)		(29.9)		(33.6)
Disposal Group, Including Discontinued Operation, Income Loss From Discontinued Operation Before Income Taxes Domestic	(5.5)		75.1		189.1		315.3
Disposal Group, Including Discontinued Operation, Income Tax Expense Benefit	14.2		26.5		80.6		116.2
(Loss) Income from Discontinued Operations - net of taxes	(19.7)		48.6		108.5		199.1
Columbia Pipeline Group Operations [Member] | Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Natural Gas Midstream Revenue	0		243.1		561.4		746.1
Disposal Group, Including Discontinued Operation, Other Revenue, Net	0		74.5		94.3		260.6
Disposal Group, Including Discontinued Operation, Revenue	0		317.6		655.7		1,006.7
Disposal Group, Including Discontinued Operation, Costs of Goods Sold	0		0		0.2		0.2
Disposal Group, Including Discontinued Operation, Gross Profit (Loss)	0		317.6		655.5		1,006.5
Disposal Group, Including Discontinued Operation, Utilities Operating Expense, Maintenance and Operations	5.5	[1]	202.1	[2]	374.8	[1]	573.3	[2]
Disposal Group, Including Discontinued Operation, Depreciation and Amortization	0		29.2		66.4		87.7
Disposal Group, Including Discontinued Operation, Impairment And Gain Loss On Sale Of Assets, Net	0		(3)		(13.6)		(20.8)
Disposal Group, Including Discontinued Operation, Taxes, Miscellaneous	0		14.6		38		50.3
Disposal Group, Including Discontinued Operation, Operating Expense	5.5		242.9		465.6		690.5
Disposal Group, Including Discontinued Operation, Income Loss From Equity Method Investments	0		12		29.1		32.9
Disposal Group, Including Discontinued Operation, Operating Income (Loss)	(5.5)		86.7		219		348.9
Disposal Group, Including Discontinued Operation, Interest Expense	0		(14.9)		(37.1)		(40.4)
Disposal Group, Including Discontinued Operation, Other Expense	0		3.5		7.8		7.8
Disposal Group, Including Discontinued Operation, Nonoperating Income Expense	0		(11.4)		(29.3)		(32.6)
Disposal Group, Including Discontinued Operation, Income Loss From Discontinued Operation Before Income Taxes Domestic	(5.5)		75.3		189.7		316.3
Disposal Group, Including Discontinued Operation, Income Tax Expense Benefit	14.2	[3]	26.6		80.9		116.6
(Loss) Income from Discontinued Operations - net of taxes	(19.7)		48.7		108.8		199.7
Corporate and Other [Member] | Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Natural Gas Midstream Revenue	0		0		0		0
Disposal Group, Including Discontinued Operation, Other Revenue, Net	0		0		0		0
Disposal Group, Including Discontinued Operation, Revenue	0		0		0		0
Disposal Group, Including Discontinued Operation, Costs of Goods Sold	0		0		0		0
Disposal Group, Including Discontinued Operation, Gross Profit (Loss)	0		0		0		0
Disposal Group, Including Discontinued Operation, Utilities Operating Expense, Maintenance and Operations	0		0		0		0
Disposal Group, Including Discontinued Operation, Depreciation and Amortization	0		0		0		0
Disposal Group, Including Discontinued Operation, Impairment And Gain Loss On Sale Of Assets, Net	0		0		0		0
Disposal Group, Including Discontinued Operation, Taxes, Miscellaneous	0		0		0		0
Disposal Group, Including Discontinued Operation, Operating Expense	0		0		0		0
Disposal Group, Including Discontinued Operation, Income Loss From Equity Method Investments	0		0		0		0
Disposal Group, Including Discontinued Operation, Operating Income (Loss)	0		0		0		0
Disposal Group, Including Discontinued Operation, Interest Expense	0		0		0		0
Disposal Group, Including Discontinued Operation, Other Expense	0		(0.2)		(0.6)		(1)
Disposal Group, Including Discontinued Operation, Nonoperating Income Expense	0		(0.2)		(0.6)		(1)
Disposal Group, Including Discontinued Operation, Income Loss From Discontinued Operation Before Income Taxes Domestic	0		(0.2)		(0.6)		(1)
Disposal Group, Including Discontinued Operation, Income Tax Expense Benefit	0		(0.1)		(0.3)		(0.4)
(Loss) Income from Discontinued Operations - net of taxes	$ 0		$ (0.1)		$ (0.3)		$ (0.6)
[1]	Includes approximately $5.5 million and $54.4 million for the three and nine months ended September 30, 2015, of transaction costs related to the Separation.
[2]	Includes approximately $9.3 million and $12.8 million for the three and nine months ended September 30, 2014, of transaction costs related to the Separation.
[3]	Primarily attributable to the write-off of consolidated state income tax benefits resulting from the Separation.

Discontinued Operations (Balanc

Discontinued Operations (Balance Sheet Disclosures) (Details) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Assets, Current		$ 0	$ 341.3
Disposal Group, Including Discontinued Operation, Assets, Noncurrent		0	7,546
Disposal Group, Including Discontinued Operation, Liabilities, Current		0	369
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		$ 0	1,616.3
Columbia Pipeline Group Operations [Member] | Discontinued Operations, Disposed of by Means Other than Sale, Spinoff [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents			0.5
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net			149.3
Disposal Group, Including Discontinued Operation, Inventory			4.8
Disposal Group, Including Discontinued Operation, Raw Materials and Supplies, Gross			24.9
Disposal Group, Including Discontinued Operation, Exchange Gas Receivable			34.8
Disposal Group, Including Discontinued Operation, Regulatory Assets, Current			6.1
Disposal Group, Including Discontinued Operation, Deferred Tax Asset, Current			57.9
Disposal Group, Including Discontinued Operation, Other Assets, Current			63
Disposal Group, Including Discontinued Operation, Assets, Current			341.3
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment, Noncurrent			4,959.7
Disposal Group, Including Discontinued Operation, Goodwill, Noncurrent			1,975.5
Disposal Group, Including Discontinued Operation, Investments In Affiliates Subsidiaries Associates And Joint Ventures			444.3
Disposal Group, Including Discontinued Operation, Other Long Term Investments			5.6
Disposal Group, Including Discontinued Operation, Regulatory Assets, Noncurrent			151.9
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent			9
Disposal Group, Including Discontinued Operation, Assets, Noncurrent			7,546
Disposal Group, Including Discontinued Operation, Accounts Payable			60.5
Disposal Group, Including Discontinued Operation, Customer Deposits, Current			13.4
Disposal Group, Including Discontinued Operation, Accrued Income Tax Payable, Current			106.9
Disposal Group, Including Discontinued Operation, Exchange Gas Payable			34.7
Disposal Group, Including Discontinued Operation, Deferred Revenue, Current			22.2
Disposal Group, Including Discontinued Operation, Regulatory Liability, Current			1.3
Disposal Group, Including Discontinued Operation, Accrued Liability for Postretirement and Postemployment Benefits, Current			0.6
Disposal Group, Including Discontinued Operation, Legal and Environmental Reserves			1.5
Disposal Group, Including Discontinued Operation, Accrued Capital Expenditures			61.1
Disposal Group, Including Discontinued Operation, Other Liabilities, Current			66.8
Disposal Group, Including Discontinued Operation, Liabilities, Current			369
Disposal Group, Including Discontinued Operation, Deferred Tax Liabilities, Noncurrent			1,272.2
Disposal Group, Including Discontinued Operation, Deferred Investment Tax Credits, Noncurrent			0.2
Disposal Group, Including Discontinued Operation, Other Deferred Credits, Noncurrent			0.2
Disposal Group, Including Discontinued Operation, Pension and Other Postretirement and Postemployment Benefit Plans Liabilities, Noncurrent	[1]		(58)
Disposal Group, Including Discontinued Operation, Regulatory Liabilities, Noncurrent			294.2
Disposal Group, Including Discontinued Operation, Asset Retirement Obligations, Noncurrent			23.2
Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent			84.3
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent			$ 1,616.3
[1]	Represents Columbia Pipeline Group segment's overfunded position in NiSource's net underfunded other postretirement plan.

Asset Retirement Obligations (C

Asset Retirement Obligations (Changes In Company's Liability For Asset Retirement Obligations) (Details) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014
Beginning Balance		$ 136.2	$ 148.1
Accretion recorded as a regulatory asset/liability		5.9	6.3
Additions		6.4	0.3
Settlements		(4.3)	(1.3)
Change in estimated cash flows	[1]	37	(7.4)
Ending Balance		$ 181.2	$ 146
[1]	The current year change in estimated cash flows is primarily attributable to estimated costs associated with the EPA's final rule for regulation of CCRs and changes to cost estimates for certain solid waste management units. See Note 16, "Other Commitments and Contingencies," for additional information on CCRs.

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) - USD ($) $ in Millions

Oct. 07, 2015

Oct. 01, 2015

Aug. 27, 2015

Apr. 16, 2015

Mar. 30, 2015

Mar. 19, 2015

Feb. 27, 2015

Apr. 30, 2014

Jul. 19, 2013

Aug. 21, 2015

Jul. 21, 2015

Apr. 22, 2015

Regulatory Matters [Line Items]

Seven Year Plan of Eligible Investments, Length of Plan

seven-year

Columbia Of Ohio [Member]

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 24.7

Columbia Of Massachusetts [Member]

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 49

Columbia Of Pennsylvania [Member]

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 28

$ 46.2

Capital Investment Program Amount

197

Capital Investment Program Amount year 2

$ 211

Columbia Of Virginia [Member]

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 31.8

Public Utilities, Approved Rate Increase (Decrease), Amount

$ 25.2

NIPSCO [Member]

Regulatory Matters [Line Items]

Seven Year Plan of Eligible Investments Under TDSIC

$ 1,100

NIPSCO [Member] | Flue Gas Desulfurization [Member]

Regulatory Matters [Line Items]

Revised Capital Expenditure Estimate

$ 255.3

Previously Approved Capital Expenditure Estimate

$ 264.8

NIPSCO [Member] | ECR 26 [Member] [Domain]

Regulatory Matters [Line Items]

Regulatory Net Capital Expenditures Included In Filing

$ 776.5

NIPSCO [Member] | TDSIC 2 Gas [Member]

Regulatory Matters [Line Items]

Regulatory Net Capital Expenditures Included In Filing

$ 43.3

NIPSCO [Member] | TDSIC 3 Gas [Member] [Domain]

Regulatory Matters [Line Items]

Regulatory Net Capital Expenditures Included In Filing

$ 75.2

Subsequent Event [Member] | Columbia Of Massachusetts [Member]

Regulatory Matters [Line Items]

Public Utilities, Approved Rate Increase (Decrease), Amount

$ 32.8

Public Utilities, Approved Rate Increase (Decrease), Amount, Year 2 and on

$ 3.6

Subsequent Event [Member] | NIPSCO [Member]

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 148

Fair Value (Narrative) (Details

Fair Value (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Fair Value Disclosure [Line Items]
Transfers between Fair Value Hierarchies			0	0
Fair Value, Assets and Liabilities Measured on a Recurring Basis			0	0
Fair Value, Assets and Liabilities Measured on a Non-Recurring Basis			0	0
Government [Member]
Fair Value Disclosure [Line Items]
Available-for-sale Securities, Gross Realized Gain (Loss)	$ 0.1	$ 0	$ 0.2	$ 0.1
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	2.2		2.2
Corporate Debt Securities [Member]
Fair Value Disclosure [Line Items]
Available-for-sale Securities, Gross Realized Gain (Loss)	0.2	$ 0.1	0.3	$ 0.3
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	$ 8.7		$ 8.7

Fair Value (Fair Value Of Finan

Fair Value (Fair Value Of Financial Assets And Liabilities Measured On A Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available-for-sale securities	$ 135.4	$ 131.9
Fair value assets measured on recurring basis, total	135.5	132
Fair value liabilities measured on recurring basis, total	16.9	14.3
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available-for-sale securities	34	28.4
Fair value assets measured on recurring basis, total	34.1	28.5
Fair value liabilities measured on recurring basis, total	16.3	14.2
Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available-for-sale securities	101.4	103.5
Fair value assets measured on recurring basis, total	101.4	103.5
Fair value liabilities measured on recurring basis, total	0	0
Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available-for-sale securities	0	0
Fair value assets measured on recurring basis, total	0	0
Fair value liabilities measured on recurring basis, total	0.6	0.1
Commodity Contract [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value assets measured on recurring basis, derivative financial instruments	0.1	0.1
Fair value liabilities measured on recurring basis, derivative financial instruments	16.9	14.3
Commodity Contract [Member] | Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value assets measured on recurring basis, derivative financial instruments	0.1	0.1
Fair value liabilities measured on recurring basis, derivative financial instruments	16.3	14.2
Commodity Contract [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value assets measured on recurring basis, derivative financial instruments	0	0
Fair value liabilities measured on recurring basis, derivative financial instruments	0	0
Commodity Contract [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value assets measured on recurring basis, derivative financial instruments	0	0
Fair value liabilities measured on recurring basis, derivative financial instruments	$ 0.6	$ 0.1

Fair Value (Available-For-Sale

Fair Value (Available-For-Sale Debt Securities) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Fair Value Disclosure [Line Items]
Amortized Cost	$ 134.8	$ 131.4
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1	1.3
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(0.4)	(0.8)
Fair Value	135.4	131.9
Government [Member]
Fair Value Disclosure [Line Items]
Amortized Cost	33.8	30.8
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0.3	0.3
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	(0.2)
Fair Value	34.1	30.9
Corporate Debt Securities [Member]
Fair Value Disclosure [Line Items]
Amortized Cost	101	100.6
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0.7	1
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(0.4)	(0.6)
Fair Value	$ 101.3	$ 101

Fair Value (Carrying Amount And

Fair Value (Carrying Amount And Estimated Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 6,576.1	$ 8,422.5
Long-term debt (including current portion), Estimated Fair Value	$ 7,286.7	$ 9,505.7

Transfers Of Financial Assets51

Transfers Of Financial Assets (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Accounts receivable securitization facility borrowings	$ 107.2	$ 284.3
Net receivables transferred	$ 107.2	$ 284.3
Columbia Gas Of Ohio Receivables Corporation [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Trade Receivable Agreement Expiration Date	Oct. 15, 2016
Net receivables transferred	$ 60
NIPSCO Accounts Receivable Corporation [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Trade Receivable Agreement Expiration Date	Aug. 24, 2016
Net receivables transferred	$ 37.2
Columbia Gas Of Pennsylvania Receivables Corporation [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Trade Receivable Agreement Expiration Date	Mar. 9, 2016
Net receivables transferred	$ 10
Maximum [Member] | Accounts Receivable Program [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Accounts receivable securitization facility borrowings	515
Maximum [Member] | Columbia Gas Of Ohio Receivables Corporation [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Trade receivables, seasonal program maximum	240
Maximum [Member] | NIPSCO Accounts Receivable Corporation [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Trade receivables, seasonal program maximum	200
Maximum [Member] | Columbia Gas Of Pennsylvania Receivables Corporation [Member]
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Trade receivables, seasonal program maximum	$ 75

Transfers Of Financial Assets52

Transfers Of Financial Assets (Schedule Of Gross And Net Receivables Transferred As Well As Short-Term Borrowings Related To The Securitization Transactions) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Gross Receivables	$ 347.9	$ 611.7
Less: Receivables not transferred	240.7	327.4
Net receivables transferred	107.2	284.3
Accounts receivable securitization facility borrowings	$ 107.2	$ 284.3

Goodwill (Table) (Details)

Goodwill (Table) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill	$ 1,690.7	$ 1,690.7
Gas Distribution Operations [Member]
Goodwill [Line Items]
Goodwill	1,690.7
Electric Operations [Member]
Goodwill [Line Items]
Goodwill	0
Corporate and Other [Member]
Goodwill [Line Items]
Goodwill	$ 0

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Taxes [Line Items]
Effective income tax rates	28.20%	3.90%	35.80%	38.70%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate			35.00%
Increase (Decrease) in Effective Tax Rate	24.30%		(2.90%)
Reduction in Income Tax Expense due to Rate Adjustment			$ 1.9
Increase in Income Tax Expense due to Rate Adjustment				$ 4.5
Changes to Liability for Uncertain Tax Positions			$ 0

Pension And Other Postretirem55

Pension And Other Postretirement Benefits (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Jul. 01, 2015
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Change in Pension Projected Benefit Obligation, net of plan assets, due to Interim Measurement		$ 22.2
Employer contributions	$ 2
Increase in regulatory assets due to Interim Measurement		21.1
Change in Accumulated Other Comprehensive Income due to Interim Measurement		1.1
Change in Net Periodic Benefit Cost due to Interim Measurement	6.4
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Change in Pension Projected Benefit Obligation, net of plan assets, due to Interim Measurement		43.6
Employer contributions	18.3
Increase in regulatory assets due to Interim Measurement		8.1
Decrease in regulatory assets due to Interim Measurement		34.8
Change in Accumulated Other Comprehensive Income due to Interim Measurement		$ 0.7
Change in Net Periodic Benefit Cost due to Interim Measurement	$ 0.8

Pension And Other Postretirem56

Pension And Other Postretirement Benefits (Components Of The Plans' Net Periodic Benefits Cost) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 7.9	$ 7.5	$ 24.3	$ 22.5
Interest cost	22.8	23.8	67	71.4
Expected return on assets	(37.3)	(39.3)	(117.7)	(117.9)
Amortization of prior service cost (credit)	0.1	0.3	0.3	0.9
Recognized actuarial loss	13.8	10.2	41.6	30.6
Total Net Periodic Benefits Cost	7.3	2.5	15.5	7.5
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service Cost	1.4	1.7	4.5	5.7
Interest cost	6.2	5.9	17.8	19.5
Expected return on assets	(5.6)	(5.1)	(15.6)	(15.1)
Amortization of prior service cost (credit)	(1.1)	(1.4)	(3.9)	(2.9)
Recognized actuarial loss	0.7	0.2	2.8	0.2
Total Net Periodic Benefits Cost	$ 1.6	$ 1.3	$ 5.6	$ 7.4

Pension And Other Postretirem57

Pension And Other Postretirement Benefits (Schedule of Significant Actuarial Assumptions) (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	4.50%	4.50%
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.19%	3.81%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	8.30%	8.30%
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.31%	3.94%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	8.15%	8.14%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	8.76%	6.90%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate	2,022	2,021

Variable Interests and Variab58

Variable Interests and Variable Interest Entities (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Schedule of Equity Method Investments [Line Items]
Payments made to Pure Air	$ 16.5	$ 17

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	May. 22, 2015	May. 18, 2015
Debt Instrument [Line Items]
Gains (Losses) on Extinguishment of Debt	$ 0		$ 0	$ (97.2)	$ 0
Nisource Finance [Member]
Debt Instrument [Line Items]
Debt Instrument Tendered		$ 750
Extinguishment of Debt, Amount		$ 1,075
Nisource Finance [Member] | 5.25% Notes Due 2017 [Member]
Debt Instrument [Line Items]
debt instrument year wise maturity date		2,017
Debt Instrument, Interest Rate, Stated Percentage							5.25%
Nisource Finance [Member] | 6.40% Notes Due 2018 [Member]
Debt Instrument [Line Items]
debt instrument year wise maturity date		2,018
Debt Instrument, Interest Rate, Stated Percentage							6.40%
Nisource Finance [Member] | 4.45% Notes Due 2021 [Member]
Debt Instrument [Line Items]
debt instrument year wise maturity date		2,021
Debt Instrument, Interest Rate, Stated Percentage							4.45%
Columbia Pipeline Group [Member] | Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 2,750

Short-Term Borrowings (Narrativ

Short-Term Borrowings (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,500
Commercial paper outstanding	0	$ 792.6
Line of Credit Facility, Amount Outstanding	$ 0	500
Revolving Credit Facility, Expiration Date	Jul. 1, 2020
Accounts receivable securitization facility borrowings	$ 107.2	284.3
Short-term borrowings	107.2	1,576.9
Letters Of Credit [Member]
Short-term Debt [Line Items]
Letters of Credit Outstanding, Amount	14.7	30.9
Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Amount Outstanding	0
Commercial Paper [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,500
Commercial paper outstanding	0
Standby Letters of Credit [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Amount Outstanding	$ 14.7	$ 14.7

Short-Term Borrowings (Schedule

Short-Term Borrowings (Schedule Of Short-Term Borrowings) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Short-term Debt [Line Items]
Commercial paper outstanding	$ 0	$ 792.6
Credit facilities borrowings	0	500
Accounts receivable securitization facility borrowings	107.2	284.3
Total short-term borrowings	107.2	$ 1,576.9
Revolving Credit Facility [Member]
Short-term Debt [Line Items]
Credit facilities borrowings	0
Commercial Paper [Member]
Short-term Debt [Line Items]
Commercial paper outstanding	$ 0
Commercial Paper/credit facilities borrowings, weighted average interest rate	0.00%	0.82%
Credit Facilities [Member]
Short-term Debt [Line Items]
Commercial Paper/credit facilities borrowings, weighted average interest rate	0.00%	1.44%
Letters Of Credit [Member]
Short-term Debt [Line Items]
Letters of Credit Outstanding, Amount	$ 14.7	$ 30.9
Standby Letters of Credit [Member]
Short-term Debt [Line Items]
Credit facilities borrowings	$ 14.7	$ 14.7

Share-Based Compensation (Narra

Share-Based Compensation (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	May. 11, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant					8,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	5,705,683		5,705,683
Allocated Share-based Compensation Expense	$ 4.2	$ 14.2	$ 15.1	$ 24.1
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	1.5	5.5	5.4	9.3
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	15.8		$ 15.8
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			1 year 9 months
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay			3.00%
Defined Contribution Plan, Cost Recognized	$ 4.8	$ 7.7	$ 19	$ 20.3
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			660,230
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value			$ 23.9
Restricted Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	967,191		967,191

Other Commitments And Conting63

Other Commitments And Contingencies (Narrative) (Details) $ in Millions	Aug. 15, 2014USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2014USD ($)
Other Commitments And Contingencies [Line Items]
Revolving credit facility, maximum		$ 1,500
Line of Credit Facility, Expiration Date		Jul. 1, 2020
Line of Credit Facility, Amount Outstanding		$ 0	$ 500
Commercial Paper		0	792.6
Guarantor Obligations, Maximum Exposure, Undiscounted		6,312.3
Recorded reserves to cover environmental remediation at various sites		125.4	126.6
Change in Liability for Estimated Future Remediation Costs		$ 0
Estimated Cost of Compliance with Clean Water Act, minimum	$ 4
Estimated Cost of Compliance with Clean Water Act, maximum	$ 35
Transmission Upgrade Agreement Multiplier		1.71
MGP Sites
Other Commitments And Contingencies [Line Items]
Number of waste disposal sites identified by program		64
Liability for Estimated Remediation Costs		$ 112.6	$ 121.5
Reasonably possible remediation costs variance from reserve		25
Guarantees Of Subsidiaries Debt [Member]
Other Commitments And Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted		6,135.5
Letters Of Credit [Member]
Other Commitments And Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted		14.7
Other Guarantees [Member]
Other Commitments And Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted		54.9
Accounts Receivable Securitization [Member]
Other Commitments And Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted		107.2
Maximum [Member] | NIPSCO [Member]
Other Commitments And Contingencies [Line Items]
Payments for Capital Improvements		860
Remaining Payments for Capital Improvements		41.8
Revolving Credit Facility [Member]
Other Commitments And Contingencies [Line Items]
Line of Credit Facility, Amount Outstanding		0
Commercial Paper [Member]
Other Commitments And Contingencies [Line Items]
Revolving credit facility, maximum		1,500
Commercial Paper		$ 0

Other Commitments And Conting64

Other Commitments And Contingencies (Existence And Expiration Of Commercial Commitments) (Details) $ in Millions	Sep. 30, 2015USD ($)
Other Commitments And Contingencies [Line Items]
Guarantee Obligations Maximum Exposure Year One	$ 337.2
Guarantee Obligations Maximum Exposure Year Two	306.2
Guarantee Obligations Maximum Exposure Year Three	267.4
Guarantee Obligations Maximum Exposure Year Four	476
Guarantee Obligations Maximum Exposure Year Five	501.7
Guarantee Obligations Maximum Exposure Thereafter	4,423.8
Guarantor Obligations, Maximum Exposure, Undiscounted	6,312.3
Guarantees of subsidiaries debt
Other Commitments And Contingencies [Line Items]
Guarantee Obligations Maximum Exposure Year One	230
Guarantee Obligations Maximum Exposure Year Two	291.5
Guarantee Obligations Maximum Exposure Year Three	267.4
Guarantee Obligations Maximum Exposure Year Four	476
Guarantee Obligations Maximum Exposure Year Five	500
Guarantee Obligations Maximum Exposure Thereafter	4,370.6
Guarantor Obligations, Maximum Exposure, Undiscounted	6,135.5
Accounts Receivable Securitization [Member]
Other Commitments And Contingencies [Line Items]
Guarantee Obligations Maximum Exposure Year One	107.2
Guarantee Obligations Maximum Exposure Year Two	0
Guarantee Obligations Maximum Exposure Year Three	0
Guarantee Obligations Maximum Exposure Year Four	0
Guarantee Obligations Maximum Exposure Year Five	0
Guarantee Obligations Maximum Exposure Thereafter	0
Guarantor Obligations, Maximum Exposure, Undiscounted	107.2
Letters Of Credit [Member]
Other Commitments And Contingencies [Line Items]
Guarantee Obligations Maximum Exposure Year One	0
Guarantee Obligations Maximum Exposure Year Two	14.7
Guarantee Obligations Maximum Exposure Year Three	0
Guarantee Obligations Maximum Exposure Year Four	0
Guarantee Obligations Maximum Exposure Year Five	0
Guarantee Obligations Maximum Exposure Thereafter	0
Guarantor Obligations, Maximum Exposure, Undiscounted	14.7
Other Guarantees [Member]
Other Commitments And Contingencies [Line Items]
Guarantee Obligations Maximum Exposure Year One	0
Guarantee Obligations Maximum Exposure Year Two	0
Guarantee Obligations Maximum Exposure Year Three	0
Guarantee Obligations Maximum Exposure Year Four	0
Guarantee Obligations Maximum Exposure Year Five	1.7
Guarantee Obligations Maximum Exposure Thereafter	53.2
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 54.9

Accumulated Other Comprehensi65

Accumulated Other Comprehensive Loss (Components Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		$ (44.4)	$ (41.4)	$ (50.6)	$ (43.6)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		(1)	(0.6)	1.3	0.2
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		1.3	0.4	3.2	1.8
Other Comprehensive Income (Loss), Net of Tax		0.3	(0.2)	4.5	2
Allocation of AOCI to Noncontrolling Interest	[1]			2
Distribution of Spinoff		24.5		24.5
Ending Balance		(19.6)	(41.6)	(19.6)	(41.6)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		0	0.5	0.3	(0.3)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		0.5	(0.5)	0.3	0.5
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		(0.2)	(0.1)	(0.3)	(0.3)
Other Comprehensive Income (Loss), Net of Tax		0.3	(0.6)	0	0.2
Allocation of AOCI to Noncontrolling Interest				0
Distribution of Spinoff		0		0
Ending Balance		0.3	(0.1)	0.3	(0.1)
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(20)	(24.5)	(23.6)	(25.8)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		(0.2)	0	(0.2)	0.1
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		0.4	0.6	2	1.8
Other Comprehensive Income (Loss), Net of Tax		0.2	0.6	1.8	1.9
Allocation of AOCI to Noncontrolling Interest				2
Distribution of Spinoff		13.9		13.9
Ending Balance		(5.9)	(23.9)	(5.9)	(23.9)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance		(24.4)	(17.4)	(27.3)	(17.5)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		(1.3)	(0.1)	1.2	(0.4)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		1.1	(0.1)	1.5	0.3
Other Comprehensive Income (Loss), Net of Tax		(0.2)	(0.2)	2.7	(0.1)
Allocation of AOCI to Noncontrolling Interest				0
Distribution of Spinoff		10.6		10.6
Ending Balance		$ (14)	$ (17.6)	$ (14)	$ (17.6)
[1]	This transaction, which occurred prior to the Separation, was distributed through retained earnings as part of the Separation on July 1, 2015.

Business Segment Information (N

Business Segment Information (Narrative) (Details)	9 Months Ended
	Sep. 30, 2015
Segment Reporting [Abstract]
Primary business segments	2
Number of counties in which electric service provided by Electric Operations	20

Business Segment Information (S

Business Segment Information (Schedule Of Operating Income Derived From Revenues And Expenses By Segment) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
Revenues	$ 817.2	$ 838.2	$ 3,554	$ 3,879.1
Consolidated Operating Income (Loss)	109.7	71.1	580.4	562.2
Gas Distribution Operations [Member]
Segment Reporting Information [Line Items]
Revenues	384.7	411.9	2,349.7	2,594.1
Consolidated Operating Income (Loss)	20	0.8	394.9	362.4
Gas Distribution Operations [Member] | Unaffiliated [Member]
Segment Reporting Information [Line Items]
Revenues	384.6	411.9	2,349.3	2,593.9
Gas Distribution Operations [Member] | Intersegment [Member]
Segment Reporting Information [Line Items]
Revenues	0.1	0	0.4	0.2
Electric Operations [Member]
Segment Reporting Information [Line Items]
Revenues	428.6	424.7	1,200.1	1,280.5
Consolidated Operating Income (Loss)	98.5	76.9	214.2	218.7
Electric Operations [Member] | Unaffiliated [Member]
Segment Reporting Information [Line Items]
Revenues	428.4	424.4	1,199.5	1,279.9
Electric Operations [Member] | Intersegment [Member]
Segment Reporting Information [Line Items]
Revenues	0.2	0.3	0.6	0.6
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Revenues	98.3	107.8	293.3	308.9
Consolidated Operating Income (Loss)	(8.8)	(6.6)	(28.7)	(18.9)
Corporate and Other [Member] | Unaffiliated [Member]
Segment Reporting Information [Line Items]
Revenues	4.2	1.9	5.2	5.3
Corporate and Other [Member] | Intersegment [Member]
Segment Reporting Information [Line Items]
Revenues	94.1	105.9	288.1	303.6
Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	$ (94.4)	$ (106.2)	$ (289.1)	$ (304.4)

Supplemental Cash Flow Inform68

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Supplemental Cash Flow [Line Items]
Capital expenditures included in current liabilities	$ 130.7	$ 117.6
Assets acquired under a capital lease	5.5	69.9
Cash paid for interest, net of interest capitalized	354.1	375
Cash paid for income taxes	$ 20.2	$ 12.2