NiSource (NI) 10-Q 1 Nov 16 2016 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Oct. 25, 2016
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Entity Registrant Name	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		322,737,775

Statements Of Consolidated Inco

Statements Of Consolidated Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net Revenues
Gas Distribution	$ 212.3	$ 208.9	$ 1,244.3	$ 1,595.5
Gas Transportation	180	172.1	689.5	739.9
Electric	465.5	428.4	1,249.2	1,198.7
Other	3.5	7.8	12.5	19.9
Total Gross Revenues	861.3	817.2	3,195.5	3,554
Cost of Sales (excluding depreciation and amortization)	218.2	209.1	949.6	1,307.3
Total Net Revenues	643.1	608.1	2,245.9	2,246.7
Operating Expenses
Operation and maintenance	336.6	311.1	1,028.9	1,076.9
Depreciation and amortization	136.3	132.5	406	391
Loss (gain) on sale of assets and impairments, net	(0.1)	1.1	(0.4)	1.2
Other taxes	56.6	53.7	178.1	197.2
Total Operating Expenses	529.4	498.4	1,612.6	1,666.3
Operating Income	113.7	109.7	633.3	580.4
Other Income (Deductions)
Interest expense, net	(85)	(94.9)	(261.5)	(285.9)
Other, net	3.5	5.8	(1.9)	11.6
Loss on early extinguishment of long-term debt	0	0	0	(97.2)
Total Other Deductions	(81.5)	(89.1)	(263.4)	(371.5)
Income from Continuing Operations before Income Taxes	32.2	20.6	369.9	208.9
Income Taxes	8.5	5.8	130.6	74.7
Income from Continuing Operations	23.7	14.8	239.3	134.2
Income (Loss) from Discontinued Operations - net of taxes	3.5	(19.7)	3.4	108.5
Net Income (Loss)	27.2	(4.9)	242.7	242.7
Less: Net income attributable to noncontrolling interest	0	0	0	15.6
Net Income (Loss) attributable to NiSource	27.2	(4.9)	242.7	227.1
Income from Continuing Operations	23.7	14.8	239.3	134.2
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	$ 3.5	$ (19.7)	$ 3.4	$ 92.9
Basic Earnings Per Share
Continuing Operations	$ 0.07	$ 0.05	$ 0.74	$ 0.42
Discontinued operations	0.01	(0.07)	0.02	0.30
Basic Earnings (Loss) Per Share	0.08	(0.02)	0.76	0.72
Diluted Earnings Per Share
Continuing operations	0.07	0.05	0.74	0.42
Discontinued operations	0.01	(0.07)	0.01	0.29
Diluted Earnings (Loss) Per Share	0.08	(0.02)	0.75	0.71
Dividends Declared Per Common Share	$ 0.165	$ 0.310	$ 0.640	$ 0.830
Basic Average Common Shares Outstanding	322,318	318,090	321,445	317,390
Diluted Average Common Shares	323,918	321,465	323,197	320,718

Statements of Consolidated Comp

Statements of Consolidated Comprehensive Income - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net Income (Loss)		$ 27.2	$ (4.9)	$ 242.7	$ 242.7
Other comprehensive income (loss):
Net unrealized gain (loss) on available-for-sale securities	[1]	(0.3)	0.3	2.2	0
Net unrealized gain (loss) on cash flow hedges	[2]	(22.6)	0.2	(146.8)	1.8
Unrecognized pension and OPEB benefit	[3]	0.2	(0.2)	0.7	2.7
Total other comprehensive income (loss)		(22.7)	0.3	(143.9)	4.5
Comprehensive Income (Loss)		4.5	(4.6)	98.8	247.2
Less: Comprehensive income attributable to noncontrolling interest		0	0	0	15.6
Comprehensive Income (Loss) attributable to NiSource		$ 4.5	$ (4.6)	$ 98.8	$ 231.6
[1]	Net unrealized gain (loss) on available-for-sale securities, net of $0.1 million tax benefit and $0.2 million tax expense in the third quarter of 2016 and 2015, respectively, and $1.2 million and zero tax expense for the nine months ended 2016 and 2015, respectively.
[2]	Net unrealized gain (loss) on derivatives qualifying as cash flow hedges, net of $14.0 million tax benefit and $0.2 million tax expense in the third quarter of 2016 and 2015, respectively, and $90.6 million tax benefit and $1.1 million tax expense for the nine months ended 2016 and 2015, respectively.
[3]	Unrecognized pension and OPEB benefit (cost), net of $0.1 million tax expense and $0.1 million tax benefit in the third quarter of 2016 and 2015, respectively, and $0.4 million and $2.1 million tax expense for the nine months ended 2016 and 2015, respectively.

Statements of Consolidated Com4

Statements of Consolidated Comprehensive Income (Parenthetical) - Parent Company - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	$ (0.1)	$ 0.2	$ 1.2	$ 0
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	(14)	0.2	(90.6)	1.1
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax	$ (0.1)	$ 0.1	$ (0.4)	$ (2.1)

Statements of Consolidated Bala

Statements of Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment
Utility Plant	$ 19,856.9	$ 18,946.9
Accumulated depreciation and amortization	(7,020.2)	(6,853.4)
Net utility plant	12,836.7	12,093.5
Other property, at cost, less accumulated depreciation	17.1	18
Net Property, Plant and Equipment	12,853.8	12,111.5
Investments and Other Assets
Unconsolidated affiliates	6.5	6.9
Other investments	200.5	187.7
Total Investments and Other Assets	207	194.6
Current Assets
Cash and cash equivalents	16.1	15.5
Restricted Cash	13.8	29.7
Accounts receivable (less reserve of $19.1 and $20.3, respectively)	471	660
Gas inventory	323.6	343.5
Materials and supplies, at average cost	100.1	86.8
Electric production fuel, at average cost	110	106.3
Exchange gas receivable	16.9	21
Regulatory assets	262.9	206.9
Prepayments and other	64.1	107.5
Total Current Assets	1,378.5	1,577.2
Other Assets
Regulatory assets	1,619.7	1,599.8
Goodwill	1,690.7	1,690.7
Intangible assets	245.4	253.7
Deferred charges and other	72.1	65
Total Other Assets	3,627.9	3,609.2
Total Assets	18,067.2	17,492.5
Common Stockholders' Equity
Common stock - $0.01 par value, 400,000,000 shares authorized; 322,564,310 and 319,110,083 shares outstanding, respectively	3.3	3.2
Treasury stock	(87.4)	(79.3)
Additional paid-in capital	5,135.6	5,078
Retained deficit	(1,060.9)	(1,123.3)
Accumulated other comprehensive loss	(179)	(35.1)
Total Common Stockholders' Equity	3,811.6	3,843.5
Long-term debt, excluding amounts due within one year	6,096.2	5,948.5
Total Capitalization	9,907.8	9,792
Current Liabilities
Current portion of long-term debt	582.6	433.7
Short-term borrowings	1,059	567.4
Accounts payable	352.2	433.4
Dividends payable	53.1	0
Customer deposits and credits	255.2	316.3
Taxes accrued	130.9	183.5
Interest accrued	71.1	129
Exchange gas payable	58.2	62.3
Regulatory liabilities	107.2	231.4
Legal and environmental	38.6	37.6
Accrued compensation and employee benefits	136	141.3
Other accruals	67.5	121.6
Total Current Liabilities	2,911.6	2,657.5
Other Liabilities and Deferred Credits
Risk management liabilities	264.5	22.6
Deferred income taxes	2,384.2	2,365.3
Deferred investment tax credits	13.8	14.8
Deferred credits	95.2	90.7
Accrued liability for postretirement and postemployment benefits	738.2	759.7
Regulatory liabilities	1,296.8	1,350.4
Asset retirement obligations	272.3	254
Other noncurrent liabilities	182.8	185.5
Total Other Liabilities and Deferred Credits	5,247.8	5,043
Commitments and Contingencies	0	0
Total Capitalization and Liabilities	$ 18,067.2	$ 17,492.5

Statements of Consolidated Bal6

Statements of Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Accounts receivable less reserve	$ 19.1	$ 20.3
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	400,000,000	400,000,000
Common Stock, Shares, Outstanding	322,564,310	319,110,083

Statements Of Consolidated Cash

Statements Of Consolidated Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating Activities
Net Income (Loss)	$ 242.7	$ 242.7
Adjustments to Reconcile Net Income to Net Cash from Continuing Operations:
Loss on early extinguishment of debt	0	97.2
Depreciation and amortization	406	391
Deferred income taxes and investment tax credits	137.7	60.1
Stock compensation expense and 401(k) profit sharing contribution	33.6	38.6
Income from discontinued operations - net of taxes	(3.4)	(108.5)
Amortization of discount/premium on debt	5.4	6.8
AFUDC equity	(8.8)	(7.7)
Other adjustments	(2.3)	11.3
Changes in Assets and Liabilities:
Accounts receivable	188.2	420.3
Inventories	(0.7)	19.8
Accounts payable	(83.2)	(287.5)
Customer deposits and credits	(61.1)	(25.5)
Taxes accrued	(51.3)	(30.6)
Interest accrued	(57.9)	(63.1)
Exchange gas receivable/payable	(0.1)	(26.1)
Other accruals	(29.8)	(57.1)
Prepayments and other current assets	43.9	30.1
Regulatory assets/liabilities	(202.2)	259.6
Postretirement and postemployment benefits	(20.9)	(61)
Deferred credits	4.6	(1.3)
Deferred charges and other noncurrent assets	(3)	10.8
Other noncurrent liabilities	(4.6)	(13.6)
Net Operating Activities from Continuing Operations	532.8	906.3
Net Operating Activities from (used for) Discontinued Operations	(0.8)	287.6
Net Cash Flows from Operating Activities	532	1,193.9
Investing Activities
Capital expenditures	(1,083.4)	(923.4)
Cash contributions from CPG	0	3,798.2
Proceeds from disposition of assets	3.4	4.3
Restricted cash withdrawals (deposits)	15.9	(3)
Cost of removal	(79.5)	(49.2)
Other investing activities	(24.6)	9.3
Net Investing Activities from (used for) Continuing Operations	(1,168.2)	2,836.2
Net Investing Activities used for Discontinued Operations	0	(430)
Net Cash Flows from (used for) Investing Activities	(1,168.2)	2,406.2
Financing Activities
Cash of CPG at separation	0	(136.8)
Issuance of long-term debt	500	0
Repayments of long-term debt and capital lease obligations	(210.9)	(1,859.1)
Premiums and other debt related costs	(0.3)	(93.5)
Change in short-term borrowings, net	491.6	(1,396.6)
Issuance of common stock	16.8	17.9
Acquisition of treasury stock	(8.1)	(20.3)
Dividends paid - common stock	(152.3)	(214)
Net Financing Activities from (used for) Continuing Operations	636.8	(3,702.4)
Net Financing Activities from Discontinued Operations	0	108.6
Net Cash Flows from (used for) Financing Activities	636.8	(3,593.8)
Change in cash and cash equivalents from continuing operations	1.4	40.1
Change in cash and cash equivalents from discontinued operations	(0.8)	(33.8)
Change in cash included in discontinued operations	0	0.5
Cash and cash equivalents at beginning of period	15.5	24.9
Cash and Cash Equivalents at End of Period	$ 16.1	$ 31.7

Statements Of Consolidated Comm

Statements Of Consolidated Common Stockholders' Equity - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Deficit	Accumulated Other Comprehensive Loss
Cumulative effect of change in accounting principle	$ 25.3	$ 0	$ 0	$ 0	$ 25.3	$ 0
Beginning Balance at Dec. 31, 2015	3,843.5	3.2	(79.3)	5,078	(1,123.3)	(35.1)
Net Income	242.7	0	0	0	242.7	0
Other comprehensive loss, net of tax	(143.9)	0	0	0	0	(143.9)
Common stock dividends ($0.64 per share)	(205.6)	0	0	0	(205.6)	0
Treasury stock acquired	(8.1)	0	(8.1)	0	0	0
Common stock	0.1	0.1	0	0	0	0
Employee stock purchase plan	3.4	0	0	3.4	0	0
Long-term incentive plan	16.9	0	0	16.9	0	0
401(k) and profit sharing	30.8	0	0	30.8	0	0
Dividend reinvestment plan	6.5	0	0	6.5	0	0
Ending Balance at Sep. 30, 2016	$ 3,811.6	$ 3.3	$ (87.4)	$ 5,135.6	$ (1,060.9)	$ (179)

Statements Of Consolidated Com9

Statements Of Consolidated Common Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Dividends Declared Per Common Share	$ 0.165	$ 0.310	$ 0.640	$ 0.830

Basis of Accounting Presentatio

Basis of Accounting Presentation	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting Presentation	Basis of Accounting Presentation 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, 2015 . 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, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements and Changes in Accounting Principles	Recent Accounting Pronouncements Recently Issued Accounting Pronouncements In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force). The pronouncement provides specific guidance on eight cash flow classification issues to reduce the diversity in practice. NiSource is required to adopt ASU 2016-15 for periods beginning after December 15, 2017, including interim periods therein. NiSource is currently evaluating the impact the adoption of ASU 2016-15 will have on the Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited). In June 2016, the FASB issued ASU 2016-13, Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . ASU 2016-13 changes the impairment model for most financial assets, replacing the current "incurred loss" model. ASU 2016-13 will require the use of an "expected loss" model for instruments measured at amortized cost and will also require entities to record allowances for available-for-sale debt securities rather than reduce the carrying amount. NiSource is required to adopt ASU 2016-13 for periods beginning after December 15, 2019, including interim periods therein. Early adoption is permitted for annual periods beginning after December 15, 2018. NiSource is currently evaluating the impact the adoption of ASU 2016-13 will have on the Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited). In May 2016, the FASB issued ASU 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients . The pronouncement clarifies implementation guidance in ASU 2014-09 on assessing collectability, noncash consideration and the presentation of sales and other similar taxes collected from customers. ASU 2016-12 has the same effective date and transition requirements as ASU 2015-14, Revenue from Contracts with Customers (Topic 606). NiSource is currently evaluating the impact the adoption of ASU 2016-12 will have on the Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited). In March 2016, the FASB issued ASU 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations. ASU 2016-08 clarifies the principal versus agent guidance in ASU 2014-09, the new revenue recognition standard. The amendment clarifies how an entity should identify the unit of accounting for the principal versus agent evaluation, and how it should apply the control principle to certain types of arrangements. ASU 2016-08 has the same effective date and transition requirements as ASU 2015-14. NiSource is currently evaluating the impact the adoption of ASU 2016-08 will have on the Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited). In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) . ASU 2016-02 introduces a lessee model that brings most leases on the balance sheet. The standard requires that lessees recognize the following for all leases (with the exception of short-term leases, as that term is defined in the standard) at the lease commencement date: (1) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and (2) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. NiSource is required to adopt ASU 2016-02 for periods beginning after December 15, 2018, including interim periods therein, and the guidance is to be applied with a modified retrospective approach, with early adoption permitted. NiSource has formed an internal stakeholder group that meets periodically to share information and gather data related to leasing activity at NiSource. NiSource has compiled a list of all active leases, and is in the process of evaluating that list to determine the ultimate impact the new standard will have on NiSource’s financial statements. As of September 30, 2016, NiSource has not determined an adoption date for ASU 2016-02. Recently Issued Accounting Pronouncements - Progress Toward Adoption NiSource has progressed in its adoption efforts related to ASU 2014-09, Revenue from Contracts with Customers (Topic 606) . An internal stakeholder group has been formed from the relevant departments at the Company to promote information sharing and communication of the new requirements. Additionally, NiSource participates in an informal forum of industry peers where questions can be asked and interpretations of the new standard can be shared. NiSource has separated its various revenue streams into high-level categories, which will serve as the basis for accounting analysis and documentation as it relates to ASU 2014-09’s impact on revenues at the Company. Substantially all of NiSource’s revenues are tariff based. As of September 30, 2016, NiSource has not concluded on an adoption date or a method of adoption for ASU 2014-09. Recently Adopted Accounting Pronouncements In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. Among other provisions, the standard requires that all excess-related income tax effects of awards are recognized in the income statement when the awards vest and are distributed and also allows an employer to make a policy election to account for forfeitures as they occur. NiSource elected to early adopt ASU 2016-09 during the third quarter of 2016. Upon adoption, NiSource elected to begin accounting for forfeitures of share-based awards as they occur. The impact of this change was not material. Additionally, NiSource recorded an adjustment to beginning retained deficit of $25.3 million . This adjustment represents excess tax benefits generated in years prior to 2016 that were previously not recognized in stockholders' equity due to NOLs in those years. Both of these adjustments were adopted on a modified retrospective basis. Lastly, NiSource recorded income tax benefits of $7.2 million related to excess tax benefits generated in 2016. These benefits were adopted on a prospective basis. However, because NiSource adopted the standard during an interim period, the standard required this $7.2 million benefit be reflected as though it was adopted as of January 1, 2016. The impact of these benefits on previously issued financial statements is summarized in the tables below: (in millions, except per share amounts) As Previously Reported Effect of Change As Adjusted Three Months Ended March 31, 2016 Income from Continuing Operations before Income Taxes $ 291.6 $ — $ 291.6 Income Taxes 111.9 (6.9 ) 105.0 Income from Continuing Operations 179.7 6.9 186.6 Income from Discontinued Operations - net of taxes — — — Net Income $ 179.7 $ 6.9 $ 186.6 Basic Earnings Per Share Continuing operations $ 0.56 $ 0.02 $ 0.58 Discontinued operations — — — Basic Earnings Per Share $ 0.56 $ 0.02 $ 0.58 Diluted Earnings Per Share Continuing operations $ 0.56 $ 0.02 $ 0.58 Discontinued operations — — — Diluted Earnings Per Share $ 0.56 $ 0.02 $ 0.58 Basic Average Common Shares Outstanding 320.3 — 320.3 Diluted Average Common Shares 322.0 0.5 322.5 (in millions, except per share amounts) As Previously Reported Effect of Change As Adjusted Three Months Ended June 30, 2016 Income from Continuing Operations before Income Taxes $ 46.1 $ — $ 46.1 Income Taxes 17.4 (0.3 ) 17.1 Income from Continuing Operations 28.7 0.3 29.0 Loss from Discontinued Operations - net of taxes (0.1 ) — (0.1 ) Net Income $ 28.6 $ 0.3 $ 28.9 Basic Earnings Per Share Continuing operations $ 0.09 $ — $ 0.09 Discontinued operations — — — Basic Earnings Per Share $ 0.09 $ — $ 0.09 Diluted Earnings Per Share Continuing operations $ 0.09 $ — $ 0.09 Discontinued operations — — — Diluted Earnings Per Share $ 0.09 $ — $ 0.09 Basic Average Common Shares Outstanding 321.7 — 321.7 Diluted Average Common Shares 322.9 0.3 323.2 (in millions, except per share amounts) As Previously Reported Effect of Change As Adjusted Six Months Ended June 30, 2016 Income from Continuing Operations before Income Taxes $ 337.7 $ — $ 337.7 Income Taxes 129.3 (7.2 ) 122.1 Income from Continuing Operations 208.4 7.2 215.6 Loss from Discontinued Operations - net of taxes (0.1 ) — (0.1 ) Net Income $ 208.3 $ 7.2 $ 215.5 Basic Earnings Per Share Continuing operations $ 0.65 $ 0.02 $ 0.67 Discontinued operations — — — Basic Earnings Per Share $ 0.65 $ 0.02 $ 0.67 Diluted Earnings Per Share Continuing operations $ 0.65 $ 0.02 $ 0.67 Discontinued operations — — — Diluted Earnings Per Share $ 0.65 $ 0.02 $ 0.67 Basic Average Common Shares Outstanding 321.0 — 321.0 Diluted Average Common Shares 322.5 0.3 322.8 None of the other provisions of this standard materially impacted NiSource's Condensed Consolidated Financial Statements (unaudited) or Notes to Condensed Consolidated Financial Statements (unaudited).

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2016
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 is as follows: Three Months Ended Nine Months Ended September 30, September 30, (in thousands) 2016 2015 2016 2015 Denominator Basic average common shares outstanding 322,318 318,090 321,445 317,390 Dilutive potential common shares: Shares contingently issuable under employee stock plans 228 — 146 — Shares restricted under employee stock plans 1,372 3,375 1,606 3,328 Diluted Average Common Shares 323,918 321,465 323,197 320,718

Discontinued Operations

Discontinued Operations	9 Months Ended
	Sep. 30, 2016
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	Discontinued Operations On July 1, 2015, NiSource completed the Separation 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, on the date of the Separation, CPG's operations consisted of NiSource's Columbia Pipeline Group Operations segment prior to the Separation. Following 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. During the third quarter of 2016, Nisource recorded a $3.6 million tax benefit resulting from favorable estimate-to-actual adjustments related to non-deductible costs from the Separation. There were no other material results from discontinued operations during 2016. Results from discontinued operations for the three and nine months ended September 30, 2015 are included in the table below. 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 Income (Loss) 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 ) Income (Loss) 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 Income (Loss) 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 of transaction costs related to the Separation for the three and nine months ended September 30, 2015, respectively. (2) Primarily attributable to the write-off of consolidated state income tax benefits resulting from 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 $31.9 million and $107.5 million for the three and nine months ended September 30, 2016 , respectively, and $31.6 million and $105.4 million for the three and nine months ended September 30, 2015, respectively. 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 TSAs. NiSource expects the TSAs to terminate within 24 months from the date of the Separation. The TSAs set forth the terms and conditions for NiSource and CPG to provide certain transition services to one another. Under the TSAs, NiSource provides CPG certain information technology, financial and accounting, human resource and other specified services. For the three and nine months ended September 30, 2016, the amounts NiSource billed CPG for these services were immaterial. There were no material assets and liabilities of discontinued operations on the Condensed Consolidated Balance Sheets (unaudited) as of September 30, 2016 and December 31, 2015.

Asset Retirement Obligations

Asset Retirement Obligations	9 Months Ended
	Sep. 30, 2016
Asset Retirement Obligation [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations Changes in NiSource’s liability for asset retirement obligations for the nine months ended September 30, 2016 and 2015 are presented in the table below: (in millions) 2016 2015 Balance as of January 1, $ 254.0 $ 136.2 Accretion recorded as a regulatory asset/liability 7.7 5.9 Additions — 6.4 Settlements (2.2 ) (4.3 ) Change in estimated cash flows 12.8 (1) 37.0 (2) Balance as of September 30, $ 272.3 $ 181.2 (1) The change in estimated cash flows for 2016 is primarily attributed to changes in estimated costs for retirement of gas mains. (2) The change in estimated cash flows for 2015 primarily represents 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 17, "Other Commitments and Contingencies," for additional information on CCRs.

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2016
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Matters	Regulatory Matters Gas Distribution Operations Regulatory Matters Significant Rate Developments . On April 30, 2013, Indiana Governor Pence signed Senate Enrolled Act 560, the TDSIC statute, into law. Among other provisions, this legislation provides for cost recovery outside of a base rate proceeding for new or replacement electric and gas transmission, distribution, and storage projects that a public utility undertakes for the purposes of safety, reliability, system modernization, or economic development. Provisions of the TDSIC statute require that, among other things, requests for recovery include a seven-year plan of eligible investments. Once the plan is approved by the IURC, 80 percent of eligible costs can be recovered using a periodic rate adjustment mechanism. The cost recovery mechanism is referred to as a TDSIC mechanism. Recoverable costs include a return on, and of, the investment, including AFUDC, post-in-service carrying charges, operation and maintenance expenses, depreciation and property taxes. The remaining 20 percent of recoverable costs are to be deferred for future recovery in the public utility’s next general rate case. The periodic rate adjustment mechanism is capped at an annual increase of no more than two percent of total retail revenues. On June 22, 2016, the IURC issued an order on TDSIC-4 approving, in all material respects, NIPSCO’s updated seven-year plan of approximately $800 million in TDSIC-eligible investments. On August 31, 2016, NIPSCO filed TDSIC-5 which included an updated seven-year plan of $824 million in TDSIC-eligible investments. An order is expected from the IURC in the fourth quarter of 2016. On March 18, 2016, Columbia of Pennsylvania filed a base rate case with the Pennsylvania PUC, seeking a revenue increase of $55.3 million annually. The case was driven by Columbia of Pennsylvania’s ongoing capital investment program which exceeded $197.0 million in 2015, and is projected to exceed $220.0 million in 2016 and $265.0 million in 2017. This case was also driven by operation and maintenance expenditures related to employee training and compliance with pipeline safety regulations. Columbia of Pennsylvania's request for rate relief included the recovery of costs that will be incurred after the implementation of new rates, as authorized by the Pennsylvania General Assembly with the passage of Act 11 of 2012. On September 2, 2016, the parties to the case filed a joint petition for settlement which provides for an annual revenue increase of $35.0 million . On September 28, 2016, the assigned administrative law judge issued a recommended decision to approve the proposed settlement, without modification. An order approving the settlement was issued from the Pennsylvania PUC on October 27, 2016, with new rates to be implemented in December 2016. On April 15, 2016, Columbia of Maryland filed a base rate case with the MPSC, seeking an annual revenue increase of $6.5 million . The case was driven by Columbia of Maryland’s ongoing capital investment program and by operations and maintenance expenditures related to compliance with pipeline safety regulations. On July 27, 2016, the parties to the case filed a joint petition for approval of a proposed settlement that includes an annual revenue increase of $3.7 million . On September 26, 2016, the assigned public utility law judge issued a proposed order approving the settlement without modification. There were no appeals to the administrative law judge's proposed order. As such, it became the order of the MPSC and new rates took effect on October 27, 2016. On April 29, 2016, Columbia of Virginia filed a request with the VSCC, seeking an annual revenue increase of $37.0 million . The case is driven by Columbia of Virginia's ongoing capital program to modernize its infrastructure and to expand and upgrade its facilities to meet customer growth, as well as expenditures related to employee training and compliance with pipeline safety regulations. A VSCC decision is expected in early 2017. Rates became effective, subject to refund, on September 28, 2016. On May 27, 2016, Columbia of Kentucky filed a base rate case with the Kentucky PSC, seeking an annual revenue increase of $25.4 million . This case was driven by Columbia of Kentucky's ongoing initiatives to improve the overall safety and reliability of its gas distribution system. On October 20, 2016, a settlement was reached which included an annual revenue increase of $13.4 million , and a hearing is scheduled for November 1, 2016. A commission decision is expected by the end of the year. Cost Recovery and Trackers . 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 those described below. 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. A significant portion of the distribution companies' revenue is related to the recovery of gas costs, the review and recovery of which occurs via standard regulatory proceedings. All states in NiSource's operating area 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 mechanisms include GCR adjustment mechanisms, tax riders, and bad debt recovery mechanisms. 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. As further discussed above in this Note 6 under the heading "Significant Rate Developments," on June 22, 2016, the IURC issued an order on TDSIC-4. The order allows NIPSCO to collect or defer for future recovery the costs associated with $145.7 million of cumulative net capital expenditures invested through December 31, 2015. On August 31, 2016, NIPSCO filed TDSIC-5 which included $211.6 million of cumulative net capital spend through June 30, 2016. An order is expected from the IURC in the fourth quarter of 2016. On November 28, 2012, the PUCO approved Columbia of Ohio’s application to extend its IRP for an additional five years, allowing Columbia of Ohio to continue to invest and recover on its accelerated main replacements. Columbia of Ohio filed its application to adjust rates associated with its IRP and DSM Riders on February 26, 2016, which requested authority to increase revenues by $25.9 million . On March 24, 2016, PUCO staff filed comments recommending that the PUCO approve Columbia of Ohio’s application. On April 20, 2016, the PUCO issued an order approving Columbia of Ohio’s application with rates going into effect April 30, 2016. On December 17, 2014, the PUCO approved Columbia of Ohio’s application to establish a regulatory asset and defer the expenditures to be incurred in implementing Columbia of Ohio’s Pipeline Safety Program. Columbia of Ohio requested authority to defer Pipeline Safety Program costs of up to $15 million annually. On March 11, 2016, Columbia of Ohio filed an application to increase the annual deferral authority from $15 million to $25 million . On June 24, 2016, Columbia of Ohio and PUCO staff filed a stipulation that recommended approval of the application in all material respects. On August 26, 2016, the PUCO approved the stipulation to increase the deferral authority to $25 million per year through January 1, 2024. On July 7, 2014, the Governor of Massachusetts signed into law Chapter 149 of the Acts of 2014, An Act Relative to Natural Gas Leaks (“the Act”). The Act authorizes natural gas distribution companies to file gas infrastructure replacement plans with the Massachusetts DPU to address the replacement of aging natural gas pipeline infrastructure. In addition, the Act provides that the Massachusetts DPU may, after review of the plans, allow the proposed estimated costs of the plan into rates as of May 1 of the subsequent year. Pursuant to the Act, on October 30, 2015, Columbia of Massachusetts filed its GSEP for the 2016 construction year (“2016 GSEP”). Columbia of Massachusetts proposed to recover an increment of $6.4 million for the costs associated with the replacement of eligible leak-prone infrastructure during the 2016 construction year for a cumulative proposed revenue requirement recovery of $9.0 million . Columbia of Massachusetts subsequently revised the cumulative proposed revenue requirement recovery to $8.2 million . The Massachusetts DPU approved the 2016 GSEP filing on April 29, 2016, with new rates effective May 1, 2016. On October 31, 2016, Columbia of Massachusetts filed its GSEP for the 2017 construction year (“2017 GSEP”). Columbia of Massachusetts is proposing to recover an increment of $8.1 million for a cumulative revenue requirement recovery of $16.8 million . An order is expected from the Massachusetts DPU in early 2017, with new rates effective May 1, 2017. On October 30, 2009, the Massachusetts DPU approved Columbia of Massachusetts's revenue decoupling mechanism that was filed in its base rate case. This allows Columbia of Massachusetts to apply annual adjustments to its peak and off-peak rates. On March 16, 2016, Columbia of Massachusetts filed its 2016 off-peak period RDAF in the amount of $3.4 million . On April 28, 2016, the Massachusetts DPU approved the rate for effect May 1, 2016. Columbia of Massachusetts's LDAF allows for the recovery of costs related to pension and other postretirement expense, low income programs, environmental remediation programs, Attorney General expert witness costs and energy efficiency programs. This allows Columbia of Massachusetts to file semi-annually to recover the cost in peak and off-peak rates. On January 29, 2016, Columbia of Massachusetts filed its 2016 off-peak period LDAF reflecting an annual recovery amount of approximately $42 million . On April 29, 2016, the Massachusetts DPU approved the rate for effect May 1, 2016. Electric Operations Regulatory Matters Significant Rate Developments . On December 31, 2015, NIPSCO filed a new electric TDSIC seven-year plan of eligible investments for a total of approximately $1.3 billion covering spend in years 2016 through 2022. On March 24, 2016, a stipulation and settlement agreement was filed with the IURC which, among other things, sought approval of a seven-year plan that includes approximately $1.25 billion of investments eligible for ratemaking treatment. On July 12, 2016, the IURC issued an order approving the settlement agreement. On October 1, 2015, NIPSCO filed an electric base rate case with the IURC, seeking a revenue increase of $126.6 million , before certain riders. As part of this filing, NIPSCO proposed to update base rates for previously incurred infrastructure improvements, revised depreciation rates and the inclusion of previously approved environmental and federally mandated compliance costs. On February 19, 2016, a stipulation and settlement agreement was filed with the IURC seeking a revenue increase of $72.5 million , before certain riders. On July 18, 2016, the IURC issued an order approving the settlement agreement as filed with new rates effective October 1, 2016. NIPSCO has been participating as one of the MISO transmission owners in defending two separate complaints filed at the FERC which challenge the MISO prescribed 12.38% base ROE for electric transmission investments subject to federal jurisdiction rate regulation. On June 30, 2016, the FERC administrative law judge issued an initial decision in the second complaint which authorized the MISO transmission owners to collect a base ROE of 9.7% for the period of February 12, 2015 through May 11, 2016. This initial decision is subject to approval by the full Commission and is not a final order. On September 28, 2016, FERC issued Opinion No. 551, which largely affirmed the initial decision in the first complaint, which set the base ROE for the MISO Transmission Owners at 10.32% for the period of November 12, 2013 through February 11, 2015. The FERC directed MISO and the MISO Transmission Owners to submit, within 30 days, a compliance filing with revised rates based on the 10.32% base ROE and to provide refunds with interest for the 15-month refund period for this case. The opinion also establishes the going forward base ROE at 10.32% as of September 28, 2016 until the Commission either issues a final order in the second complaint or a new proceeding is initiated to create a new refund period. Incorporating NIPSCO’s 50-basis point adder for independent RTO membership, NIPSCO’s total ROE is set at 10.82% going forward. NIPSCO has an estimated liability of $5.3 million at September 30, 2016 related to this matter. 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 quarterly, 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 and (2) related operation and maintenance and depreciation expenses once the environmental facilities become operational. On November 1, 2016, NIPSCO filed a petition with the IURC for relief regarding the construction of additional environmental projects required to comply with the final rules for regulation of CCRs and the ELG. Refer to Note 17-C, “Environmental Matters,” for more information. On April 20, 2016, the IURC issued an order on ECR-27 approving NIPSCO’s request to begin earning a return on $800.7 million of cumulative net capital expenditures invested through December 31, 2015. A significant portion of the net capital expenditures related to ECR-27 were included in the base rates effective October 1, 2016 as a component of NIPSCO's electric base rate case settlement on July 18, 2016. On October 26, 2016 , the IURC issued an order on ECR-28 approving NIPSCO’s request to begin earning a return on $267.0 million of cumulative net capital expenditures invested through June 30, 2016. Consistent with the terms of the aforementioned electric TDSIC settlement agreement, NIPSCO made a TDSIC rate adjustment mechanism filing on June 30, 2016 seeking recovery and ratemaking relief associated with $45.5 million of cumulative net capital expenditures invested through April 30, 2016. New rates are expected to go into effect February 1, 2017. NIPSCO received a final order from the IURC related to its original TDSIC plan as of January 16, 2016. That order authorized NIPSCO to defer, as a regulatory asset, 100% of all TDSIC costs incurred from March 1, 2014 through December 31, 2015 until such deferral is recovered as part of its next general rate case. As discussed above, the electric general rate case was approved on July 18, 2016, which allows for recovery in base rates of 100% of these previously incurred TDSIC costs. This approval allowed NIPSCO to record a regulatory asset of approximately $7.8 million in the third quarter of 2016.

Risk Management Activities

Risk Management Activities	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Risk Management Activities	Risk Management Activities NiSource is exposed to certain risks relating to its ongoing business operations; namely commodity price risk and interest rate risk. NiSource recognizes that the prudent and selective use of derivatives may help to lower its cost of debt capital, manage its interest rate exposure and limit volatility in the price of natural gas. Commodity Price Risk Management NiSource and NiSource’s utility customers are exposed to variability in cash flows associated with natural gas purchases and volatility in natural gas prices. NiSource purchases natural gas for sale and delivery to its retail, commercial and industrial customers, and for most customers the variability in the market price of gas is passed through in their rates. Some of NiSource’s utility subsidiaries offer programs where variability in the market price of gas is assumed by the respective utility. The objective of NiSource’s commodity price risk programs is to mitigate the gas cost variability, for NiSource or on behalf of its customers, associated with natural gas purchases or sales by economically hedging the various gas cost components using a combination of futures, options, forwards or other derivative contracts. In September 2016, NIPSCO received IURC approval to lock in a fixed price for its natural gas customers using long-term forward purchase instruments. The term of these instruments may range from five to ten years and is limited to ten percent of NIPSCO’s average annual GCA purchase volume. Gains and losses on these derivative contracts will be deferred as regulatory liabilities or assets, and will be remitted to or collected from customers through NIPSCO’s quarterly GCA mechanism. Activity related to these newly approved long-term gas purchase contracts as of September 30, 2016 was not material. These instruments are not designated as accounting hedges. Interest Rate Risk Management In June 2016, NiSource Finance entered into additional forward-starting interest rate swap agreements with an aggregate notional value of $500.0 million to hedge the variability in cash flows attributable to changes in the benchmark interest rate during the periods from the effective dates of the swaps to the anticipated dates of forecasted debt issuances, which are expected to take place by the end of 2018 . As of September 30, 2016, NiSource Finance has forward-starting interest rate swaps with an aggregate notional value totaling $1.5 billion . These interest rate swaps are designated as cash flow hedges. The effective portions of the gains and losses related to these swaps are recorded to AOCI and are recognized in earnings concurrent with the recognition of interest expense on the associated debt, once issued. If it becomes probable that a hedged forecasted transaction will no longer occur, the accumulated gains or losses on the derivative will be recognized currently in earnings. Earnings may also be impacted if the anticipated dates of forecasted debt issuances differ from the dates originally contemplated at hedge inception. Realized gains and losses from NiSource’s interest rate cash flow hedges are presented in “Interest expense, net” on the Condensed Statements of Consolidated Income (Loss) (unaudited). Derivative assets and liabilities on NiSource’s interest rate cash flow hedges are presented as “Risk management assets” and “Risk management liabilities,” respectively, on the Condensed Consolidated Balance Sheets (unaudited). NiSource had $256.8 million and $17.4 million of derivative liabilities related to these cash flow hedges as of September 30, 2016 and December 31, 2015 , respectively. $250.0 million of the interest rate swaps are set to terminate within the next twelve months. There was no material income statement recognition of gains or losses relating to an ineffective portion of NiSource's hedges, nor were there amounts excluded from effectiveness testing for derivatives in cash flow hedging relationships for the three and nine months ended September 30, 2016 and 2015. NiSource’s derivative instruments measured at fair value as of September 30, 2016 and December 31, 2015 do not contain any credit-risk-related contingent features.

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2016
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, 2016 and December 31, 2015 : 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 September 30, 2016 Assets Risk management assets $ 1.9 $ 5.7 $ — $ 7.6 Available-for-sale securities — 137.1 — 137.1 Total $ 1.9 $ 142.8 $ — $ 144.7 Liabilities Risk management liabilities (1) $ 4.5 $ 266.5 $ 0.1 $ 271.1 Total $ 4.5 $ 266.5 $ 0.1 $ 271.1 (1) Includes $6.6 million of current risk management liabilities which are included in "Other accruals" on the Condensed Consolidated Balance Sheets (unaudited). 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, 2015 Assets Risk management assets $ 0.1 $ — $ — $ 0.1 Available-for-sale securities — 128.7 — 128.7 Total $ 0.1 $ 128.7 $ — $ 128.8 Liabilities Risk management liabilities (1) $ 14.3 $ 17.4 $ 0.2 $ 31.9 Total $ 14.3 $ 17.4 $ 0.2 $ 31.9 (1) Includes $9.3 million of current risk management liabilities which are included in "Other accruals" on the Condensed Consolidated Balance Sheets (unaudited). Risk management assets and liabilities include interest rate swaps, exchange-traded NYMEX futures and NYMEX options and non-exchange-based forward purchase 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 within 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 within 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, 2016 and December 31, 2015 , 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. NiSource Finance has entered into forward-starting interest rate swaps to hedge the interest rate risk on coupon payments of forecasted issuances of long-term debt. These swaps are designated as cash flow hedges. Credit risk is considered in the fair value calculation of each interest rate swap. As they are based on observable data and valuations of similar instruments, the interest rate swaps are categorized within Level 2 of the fair value hierarchy. There was no exchange of premium at the initial date of the swaps, and NiSource can settle the swaps at any time. For additional information see Note 7, "Risk Management Activities." 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). NiSource values U.S. Treasury, corporate and mortgage-backed 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 securities at September 30, 2016 and December 31, 2015 were: September 30, 2016 (in millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities U.S. Treasury securities $ 37.4 $ 0.9 $ — $ 38.3 Corporate/Other debt securities 97.1 1.9 (0.2 ) 98.8 Total Available-for-sale securities $ 134.5 $ 2.8 $ (0.2 ) $ 137.1 December 31, 2015 (in millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities U.S. Treasury securities $ 33.7 $ 0.1 $ (0.3 ) $ 33.5 Corporate/Other debt securities 95.7 0.3 (0.8 ) 95.2 Total Available-for-sale securities $ 129.4 $ 0.4 $ (1.1 ) $ 128.7 For the three months ended September 30, 2016 and 2015 , the net realized gain on the sale of available-for-sale U.S. Treasury debt securities was zero and $0.1 million , respectively. For the three months ended September 30, 2016 and 2015 , the net realized gain on the sale of available-for-sale Corporate/Other debt securities was zero and $0.2 million , respectively. For the nine months ended September 30, 2016 and 2015 , the net realized gain on the sale of available-for-sale U.S. Treasury debt securities was zero and $0.2 million , respectively. For the nine months ended September 30, 2016 and 2015 , the net realized gain on the sale of available-for-sale Corporate/Other debt securities was $0.1 million and $0.3 million , respectively. The cost of maturities sold is based upon specific identification. At September 30, 2016 , approximately $2.8 million of U.S. Treasury securities and approximately $15.5 million of Corporate/Other debt securities have maturities of less than a 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, 2016 and 2015 . Non-recurring Fair Value Measurements. There were no significant non-recurring fair value measurements recorded during the nine months ended September 30, 2016 . 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 method and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate fair value. Long-term Debt. The fair value of outstanding long-term debt is 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 within Level 2 of the fair value hierarchy. For the nine months ended September 30, 2016 there was no change in the method or significant assumptions used to estimate the fair value of long-term debt. The carrying amount and estimated fair values of these financial instruments were as follows: (in millions) Carrying Estimated Fair Carrying Amount as of Dec. 31, 2015 Estimated Fair Value as of Dec. 31, 2015 Long-term debt (including current portion) $ 6,678.8 $ 7,639.9 $ 6,382.2 $ 6,975.7

Transfers Of Financial Assets

Transfers Of Financial Assets	9 Months Ended
	Sep. 30, 2016
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 BTMU and a commercial paper conduit sponsored by BNS. T his agreement was last renewed on October 14, 2016; the current agreement expires on October 13, 2017 , 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, 2016 , $75.0 million of accounts receivable had been transferred by CGORC. CGORC is a separate corporate entity from NiSource and Columbia of Ohio, with 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 Mizuho. This agreement was last renewed on August 24, 2016; the current agreement expires on August 23, 2017 , 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, 2016 , $150.0 million of accounts receivable had been transferred by NARC. NARC is a separate corporate entity from NiSource and NIPSCO, with 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 9, 2016; the current agreement expires on March 8, 2017 , 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, 2016 , $10.0 million of accounts receivable had been transferred by CPRC. CPRC is a separate corporate entity from NiSource and Columbia of Pennsylvania, with 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, 2016 and December 31, 2015 for Columbia of Ohio, NIPSCO and Columbia of Pennsylvania: (in millions) September 30, 2016 December 31, 2015 Gross Receivables $ 361.6 $ 450.8 Less: Receivables not transferred 126.6 204.8 Net receivables transferred $ 235.0 $ 246.0 Short-term debt due to asset securitization $ 235.0 $ 246.0 Cash flows used for financing activities related to the change in short-term borrowings due to the securitization transactions were $11.0 million and $177.1 million for the nine months ended September 30, 2016 and 2015, respectively. Fees associated with securitization transactions were recorded as interest expense of $0.4 million and $0.5 million for the three months ended September 30, 2016 and 2015, respectively, and $1.6 million and $1.9 million for the nine months ended September 30, 2016 and 2015, respectively. 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, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill The following presents NiSource’s goodwill balance allocated by segment as of September 30, 2016 : (in millions) Gas Distribution Operations Electric Operations Corporate and Other Total Goodwill $ 1,690.7 $ — $ — $ 1,690.7 NiSource completed a quantitative ("step 1") fair value measurement of its reporting units during the May 1, 2016 goodwill test. The test indicated that the fair value of each of the reporting units that are allocated goodwill exceeded their carrying values, indicating that no impairment was necessary.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes NiSource’s interim effective tax rates reflect the estimated annual effective tax rates for 2016 and 2015, adjusted for tax expense associated with certain discrete items. The effective tax rates for the three months ended September 30, 2016 and 2015 were 26.4% and 28.2% , respectively. The effective tax rates for the nine months ended September 30, 2016 and 2015 were 35.3% and 35.8% , 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. The decrease in the three month effective tax rate of 1.8% in 2016 versus the same period in 2015 is primarily due to favorable estimate-to-actual adjustments related to 2015 tax returns and estimated state apportionment benefits for 2016, partially offset by a 2015 cumulative adjustment to the estimated annual effective tax rate. The decrease in the year-to-date effective tax rate of 0.5% in 2016 versus the same period in 2015 is primarily due to 2016 excess stock compensation benefits from the adoption of ASU 2016-09, offset by differences in state apportionment benefits between 2016 and 2015. Refer to Note 2, "Recent Accounting Pronouncements," for additional information. There were no material changes recorded in 2016 to NiSource's uncertain tax positions as of December 31, 2015 .

Pension And Other Postretiremen

Pension And Other Postretirement Benefits	9 Months Ended
	Sep. 30, 2016
Pension and Other Postretirement Benefit Expense [Abstract]
Pension And Other Postretirement Benefits	Pension and Other Postretirement Benefits NiSource provides defined contribution plans and noncontributory defined benefit retirement plans that cover certain of 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. For most plans, cash contributions are remitted to grantor trusts. For the nine months ended September 30, 2016 , NiSource contributed $2.7 million to its pension plans and $18.6 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, 2016 and 2015 : Pension Benefits Other Postretirement Benefits Three Months Ended September 30, (in millions) 2016 2015 2016 2015 Components of Net Periodic Benefit Cost Service cost $ 7.7 $ 7.9 $ 1.3 $ 1.4 Interest cost 22.4 22.8 5.5 6.2 Expected return on assets (33.2 ) (37.3 ) (4.3 ) (5.6 ) Amortization of prior service cost (credit) — 0.1 (1.2 ) (1.1 ) Recognized actuarial loss 15.3 13.8 0.8 0.7 Total Net Periodic Benefit Cost $ 12.2 $ 7.3 $ 2.1 $ 1.6 Pension Benefits Other Postretirement Benefits Nine Months Ended September 30, (in millions) 2016 2015 2016 2015 Components of Net Periodic Benefit Cost Service cost $ 23.1 $ 24.3 $ 3.7 $ 4.5 Interest cost 67.2 67.0 16.5 17.8 Expected return on assets (99.6 ) (117.7 ) (12.9 ) (15.6 ) Amortization of prior service cost (credit) (0.2 ) 0.3 (3.6 ) (3.9 ) Recognized actuarial loss 45.9 41.6 2.4 2.8 Total Net Periodic Benefit Cost $ 36.4 $ 15.5 $ 6.1 $ 5.6

Variable Interests and Variable

Variable Interests and Variable Interest Entities	9 Months Ended
	Sep. 30, 2016
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 would consolidate those VIEs for which it was 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 $16.0 million and $16.5 million for the nine months ended September 30, 2016 and 2015 , respectively.

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2016
Long-term Debt, Current and Noncurrent [Abstract]
Long-term Debt	Long-Term Debt NiSource Finance is a 100% owned, consolidated finance subsidiary of NiSource that engages in financing activities to raise funds for the business operations of NiSource and its subsidiaries. NiSource Finance obligations are fully and unconditionally guaranteed by NiSource. Consequently, no separate financial statements for NiSource Finance are required to be reported. No NiSource subsidiaries guarantee debt. In June 2016, NiSource Finance entered into forward-starting interest rate swaps with an aggregate notional amount of $500.0 million to hedge the variability in cash flows attributable to changes in the benchmark interest rate during the period from the effective date of the swaps to the anticipated date of forecasted debt issuances, expected to take place by the end of 2018 . The forward-starting interest rate swaps were designated as cash flow hedges at the time the agreements were executed, whereby any gain or loss recognized from the effective date of the swaps to the date the associated debt is issued for the effective portion of the hedge is recorded net of tax in AOCI and amortized as a component of interest expense over the life of the designated debt. If some portion of the hedges becomes ineffective, the associated gain or loss will be recognized in earnings. As of September 30, 2016 , no ineffectiveness has been recorded. On March 31, 2016, NiSource Finance entered into a $500.0 million term loan agreement with a syndicate of banks. The term loan matures March 29, 2019, at which point any and all outstanding borrowings under the agreement are due. Interest charged on borrowings depends on the variable rate structure elected by NiSource Finance at the time of each borrowing. The available variable rate structures from which NiSource Finance may choose are defined in the term loan agreement. As of September 30, 2016 , NiSource had $500.0 million of outstanding borrowings under the term loan agreement. On March 15, 2016, NiSource Finance redeemed $201.5 million of 10.75% senior unsecured notes at maturity.

Short-Term Borrowings

Short-Term Borrowings	9 Months Ended
	Sep. 30, 2016
Short-term Debt [Abstract]
Short-Term Borrowings	Short-Term Borrowings NiSource Finance currently maintains 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 for general corporate purposes. At September 30, 2016 and December 31, 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. As of September 30, 2016 and December 31, 2015 , NiSource had $824.0 million and $321.4 million , respectively, of commercial paper outstanding. As of September 30, 2016 and December 31, 2015 , NiSource had $14.7 million of stand-by letters of credit outstanding, all of which 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 $235.0 million and $246.0 million as of September 30, 2016 and December 31, 2015 , respectively. Refer to Note 9, "Transfers of Financial Assets," for additional information. (in millions) September 30, December 31, Commercial Paper weighted-average interest rate of 1.07% and 1.00% at September 30, 2016 and December 31, 2015, respectively $ 824.0 $ 321.4 Accounts receivable securitization facility borrowings 235.0 246.0 Total Short-Term Borrowings $ 1,059.0 $ 567.4 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, 2016
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. At September 30, 2016 , there were 4,991,665 shares reserved for future awards under the Omnibus Plan. NiSource recognized stock-based employee compensation expense of $3.6 million and $4.2 million for the three months ended September 30, 2016 and 2015 , respectively, as well as related tax benefits of $1.4 million and $1.5 million , respectively. For the nine months ended September 30, 2016 and 2015 , stock-based employee compensation expense of $11.1 million and $15.1 million was recognized, respectively, as well as related tax benefits of $4.3 million and $5.4 million , respectively. Additionally, NiSource adopted ASU 2016-09 in the third quarter of 2016 and recognized excess tax benefits from the distribution of vested share-based employee compensation in 2016. For the three and nine months ended September 30, 2016 , zero and $7.2 million of such benefits were recorded, respectively. Refer to Note 2, "Recent Accounting Pronouncements," for additional information. As of September 30, 2016 , the total remaining unrecognized compensation cost related to non-vested awards amounted to $17.6 million , which will be amortized over the weighted-average remaining requisite service period of 1.9 years . Restricted Stock Units and Restricted Stock. During the nine months ended September 30, 2016 , NiSource granted 62,031 restricted stock units and shares of restricted stock, subject to service conditions. The total grant date fair value of the restricted stock units and shares of restricted stock was $1.3 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 over the vesting period which is generally three years. As of September 30, 2016 , 1,670,941 non-vested (all of which are expected to vest) restricted stock units and shares of restricted stock were granted and outstanding. Performance Shares. During the nine months ended September 30, 2016 , NiSource granted 647,305 performance shares subject to service, performance and market conditions. The grant date fair value of the awards was $12.6 million , based on the average market price of NiSource’s common stock at the date of each grant less the present value of dividends not received during the vesting period which will be expensed over the vesting period which is generally three years. A Monte Carlo analysis was used to value the portion of these awards dependent on market conditions. As of September 30, 2016 , 647,305 non-vested (all of which are expected to vest) performance shares 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 NiSource common stock. NiSource also has a retirement savings plan that provides for discretionary profit sharing contributions payable in shares of NiSource common stock to eligible employees based on earnings results; and eligible 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, 2016 and 2015 , NiSource recognized 401(k) match, profit sharing and non-elective contribution expense of $8.3 million and $4.8 million , respectively. For each of the nine months ended September 30, 2016 and 2015 , NiSource recognized 401(k) match, profit sharing and non-elective contribution expenses of $22.5 million and $19.0 million , respectively.

Other Commitments And Contingen

Other Commitments And Contingencies	9 Months Ended
	Sep. 30, 2016
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. At September 30, 2016 , NiSource had issued stand-by letters of credit of approximately $14.7 million for the benefit of third parties. 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. 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 the 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, 2016 and December 31, 2015 , NiSource had recorded a liability of approximately $116.9 million and $123.2 million , respectively, to cover environmental remediation at various sites. The current portion of this liability 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 recognizes 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. These expenditures are not currently estimable at some sites. NiSource periodically adjusts its liability 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, including implementation of the EPA CPP, could significantly limit allowed GHG emissions or impose a cost or tax on GHG emissions. Additionally, certain rules that increase methane leak detection and permitting requirements for natural gas facilities could restrict GHG emissions or impose additional costs. The CPP and other federally enacted or proposed GHG reduction measures are subject to numerous legal challenges that could change the way the programs are implemented, and NiSource will carefully monitor all GHG reduction proposals and regulations. In addition to the federal programs, the United States and 194 other countries agreed by consensus to limit GHGs to NDCs beginning after 2020 in the 2015 United Nations Framework Convention on Climate Change Paris Agreement. The United States has proposed a NDC of a 26-28% reduction from 2005 levels by 2025, a figure that cannot be met with the CPP alone. 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 or contribute significantly to nonattainment of downwind states may be required to take steps to achieve and maintain 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 26, 2015, the EPA issued a 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 in attainment with the standards may be reclassified as nonattainment. 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, 2016. The total estimated liability at NiSource related to the facilities subject to remediation was $108.3 million and $110.4 million at September 30, 2016 and December 31, 2015 , 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. Compliance estimates disclosed below are reflective of NIPSCO's Integrated Resource Plan submitted to the IURC on November 1, 2016. See section D, "Other Matters" below for additional information. Air NIPSCO is subject to a number of air-quality mandates. The mandates, which include the NSR Consent Decree, the MATS, the CPP and the Cross State Air Pollution Rule, have required and may require NIPSCO to make capital improvements to its electric generating stations. NIPSCO has made substantially all of the capital improvements necessary to comply with the NSR Consent Decree and the MATS. NIPSCO will incur future maintenance and monitoring costs to ensure continued compliance with the regulations. These costs are not expected to be material. A significant portion of the compliance costs have been or are currently being collected through rates. NIPSCO believes ongoing maintenance and monitoring costs will be eligible for recovery through rates. Clean Power Plan : On October 23, 2015, the EPA issued a final rule to regulate CO 2 emissions from existing fossil-fuel EGUs under section 111(d) of the CAA. The final rule establishes national CO 2 emission-rate standards that are applied to each state’s mix of affected EGUs to establish 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. If a state does not submit a satisfactory plan, the EPA will impose a federal plan on that state. On February 9, 2016, the U.S. Supreme Court stayed implementation of the CPP until litigation is decided on its merits. The cost to comply with this rule will depend on a number of factors, including the outcome of CPP litigation, the requirements of the state plan or final federal plan, and the level of NIPSCO's required CO 2 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. Should costs be incurred to comply with the CPP, NIPSCO believes such costs will be eligible for recovery through rates. Cross State Air Pollution Rule: On September 7, 2016, the EPA issued a final rule to address interstate air quality impacts associated with the 2008 ozone NAAQS. Under the final rule, NIPSCO is required to meet a more stringent NOx emission allocation. Based on current projections, NIPSCO does not anticipate that this matter will have a material financial impact. Water On August 15, 2014, the EPA issued 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 zero and $35 million , dependent upon study results, agency requirements and technology ultimately required to achieve compliance. On November 3, 2015, the EPA issued a final rule to amend the ELG and standards for the Steam Electric Power Generating category. The final rule became effective January 4, 2016. The rule imposes new water treatment and discharge requirements on NIPSCO's electric generating facilities to be applied between 2018-2023. Based upon a preliminary engineering study, capital compliance costs are currently expected to cost approximately $170 million . NIPSCO believes that the costs associated with ELG compliance will be eligible for recovery through rates. Waste On April 17, 2015, the EPA issued 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 nonhazardous. The rule will require increased groundwater monitoring, reporting, record keeping and posting of 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, to comply with the rule, NIPSCO will be required to incur future capital expenditures to modify its infrastructure and manage CCRs. Based upon a preliminary engineering study, capital compliance costs are currently expected to cost approximately $230 million . As allowed by the EPA, NIPSCO will continue to collect data over time to determine the specific compliance solutions and associated costs and, as a result, the actual costs may vary. NIPSCO believes that the costs associated with CCR compliance will be eligible for recovery through rates. D. Other Matters. Transmission Upgrade Agreements. On February 11, 2014, NIPSCO entered into 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. On August 10, 2016, NIPSCO reached settlement with all remaining parties to the complaint and filed with the FERC for approval. An order from the Commission is pending. NIPSCO will continue to monitor developments in this matter and does not believe the conclusion of this matter will result in a material impact to the Condensed Consolidated Financial Statements (unaudited). At the time the TUAs were executed, it was assumed the proceeds received from the upgrade sponsors would be taxable to NIPSCO. Accordingly, the multiplier included a provision for such taxes. On June 10, 2016, the US Treasury Department issued a notice regarding transfers of property to regulated utilities by electric generators, stating that transfers within the scope of the notice will not be treated as taxable. In response to this notice, NIPSCO recorded a liability of $8.6 million to reflect the estimated amount owed to the upgrade sponsors for the portion of the multiplier previously collected for taxes. This activity is recorded within "Other, net" in the Condensed Statements of Consolidated Income (Loss) (unaudited). Pipeline Safety. On March 17, 2016, PHMSA issued a proposed rule that would, if adopted, add new assessment and data requirements to existing transmission facilities that would necessitate expanded investigation and repair/replace activity on these facilities over the next 15 years. The comment period for the proposed rule closed on July 7, 2016. If adopted as proposed, this rule may require NiSource to incur significant incremental capital and operation and maintenance expenditures to achieve compliance. NiSource will continue to monitor this matter, and cannot reasonably estimate its impact at this time. NIPSCO 2016 Integrated Resource Plan. Environmental, regulatory and economic factors, including low natural gas prices and aging coal-fired units, have led NIPSCO to consider modifying its current electric generation supply mix to include less coal-fired generation. Due to enacted CCR and ELG legislation, NIPSCO would expect to incur over $1 billion in operating, maintenance, environmental and other costs over the next seven years if the current fleet of coal-fired generating units remain operational. On November 1, 2016, NIPSCO submitted its 2016 Integrated Resource Plan with the IURC. The plan evaluates demand-side and supply-side resource alternatives to reliably and cost effectively meet NIPSCO customers' future energy requirements over the next twenty years. The 2016 Integrated Resource Plan indicates that the most viable option for customers and NIPSCO involves the retirement of Bailly Generating Station (Units 7 and 8) as soon as mid-2018 and two units (Units 17 and 18) at the R.M. Schahfer Generating Station by the end of 2023. It is projected over the long term that the cost to customers to retire these units at these dates will be lower than maintaining and upgrading them for continuing generation. NiSource and NIPSCO committed to the retirement of the Bailly Generating Station units in connection with the filing of the 2016 Integrated Resource Plan. However, retirement of these units is subject to the approval of MISO, which is responsible for coordinating, controlling and monitoring the use of the electric transmission system by utilities, generators and marketers across parts of 15 U.S. states and the Canadian province of Manitoba. NIPSCO currently expects MISO to be ready to render its decision with respect to the retirement of the Bailly units in late November or early December of 2016. NiSource expects to incur approximately $16 million in contract termination costs in connection with early retirement of these units at Bailly. NiSource also expects to incur charges related to voluntary employee severance benefits ranging from $10 million to $15 million . NiSource expects to incur such charges, totaling $26 million to $31 million , if and when MISO approval is received. Additionally, if NiSource is ultimately not permitted to fully recover the net book value of the Bailly units, it could reduce future net income and cash flows.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 30, 2016
Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The following tables display the components of Accumulated Other Comprehensive Loss for the three and nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, 2016 (in millions) Gains and Losses on 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, 2016 $ 2.0 $ (139.7 ) $ (18.6 ) $ (156.3 ) Other comprehensive loss before reclassifications (0.3 ) (22.9 ) — (23.2 ) Amounts reclassified from accumulated other comprehensive loss — 0.3 0.2 0.5 Net current-period other comprehensive income (loss) (0.3 ) (22.6 ) 0.2 (22.7 ) Balance as of September 30, 2016 $ 1.7 $ (162.3 ) $ (18.4 ) $ (179.0 ) Nine Months Ended September 30, 2016 (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, 2016 $ (0.5 ) $ (15.5 ) $ (19.1 ) $ (35.1 ) Other comprehensive income (loss) before reclassifications 2.3 (148.0 ) — (145.7 ) Amounts reclassified from accumulated other comprehensive loss (0.1 ) 1.2 0.7 1.8 Net current-period other comprehensive income (loss) 2.2 (146.8 ) 0.7 (143.9 ) Balance as of September 30, 2016 $ 1.7 $ (162.3 ) $ (18.4 ) $ (179.0 ) 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 (1) Balance as of July 1, 2015 $ — $ (20.0 ) $ (24.4 ) $ (44.4 ) Other comprehensive income (loss) before reclassifications 0.5 (0.2 ) (1.3 ) (1.0 ) Amounts reclassified from accumulated other comprehensive loss (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 (Refer to Note 4, "Discontinued Operations") — 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 (loss) before reclassifications 0.3 (0.2 ) 1.2 1.3 Amounts reclassified from accumulated other comprehensive loss (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 (Refer to Note 4, "Discontinued Operations") — 13.9 10.6 24.5 Balance as of September 30, 2015 $ 0.3 $ (5.9 ) $ (14.0 ) $ (19.6 ) (1) All amounts are net of tax. Amounts in parentheses indicate debits.

Business Segment Information

Business Segment Information	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Business Segment Information	Business Segment Information At September 30, 2016 , NiSource’s operations are divided into two primary reportable 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 (in millions) 2016 2015 2016 2015 Revenues Gas Distribution Operations Unaffiliated $ 392.4 $ 384.6 $ 1,935.6 $ 2,349.3 Intersegment 3.1 0.1 9.6 0.4 Total 395.5 384.7 1,945.2 2,349.7 Electric Operations Unaffiliated 465.4 428.4 1,249.2 1,199.5 Intersegment 0.4 0.2 0.6 0.6 Total 465.8 428.6 1,249.8 1,200.1 Corporate and Other Unaffiliated 3.5 4.2 10.7 5.2 Intersegment 100.5 94.1 298.1 288.1 Total 104.0 98.3 308.8 293.3 Eliminations (104.0 ) (94.4 ) (308.3 ) (289.1 ) Consolidated Gross Revenues $ 861.3 $ 817.2 $ 3,195.5 $ 3,554.0 Operating Income (Loss) Gas Distribution Operations $ 4.3 $ 20.0 $ 392.7 $ 394.9 Electric Operations 112.8 98.5 251.5 214.2 Corporate and Other (3.4 ) (8.8 ) (10.9 ) (28.7 ) Consolidated Operating Income $ 113.7 $ 109.7 $ 633.3 $ 580.4

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	9 Months Ended
	Sep. 30, 2016
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information The following table provides additional information regarding NiSource’s Condensed Statements of Consolidated Cash Flows (unaudited) for the nine months ended September 30, 2016 and 2015 : Nine Months Ended (in millions) 2016 2015 Supplemental Disclosures of Cash Flow Information Non-cash transactions: Capital expenditures included in current liabilities $ 131.2 $ 130.7 Assets acquired under a capital lease 4.0 5.5 Schedule of interest and income taxes paid: Cash paid for interest, net of interest capitalized $ 305.5 $ 354.1 Cash paid for income taxes 5.8 20.2

Recent Accounting Pronounceme30

Recent Accounting Pronouncements (Tables)	9 Months Ended
	Sep. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Schedule of Prospective Adoption of New Accounting Pronouncements	The impact of these benefits on previously issued financial statements is summarized in the tables below: (in millions, except per share amounts) As Previously Reported Effect of Change As Adjusted Three Months Ended March 31, 2016 Income from Continuing Operations before Income Taxes $ 291.6 $ — $ 291.6 Income Taxes 111.9 (6.9 ) 105.0 Income from Continuing Operations 179.7 6.9 186.6 Income from Discontinued Operations - net of taxes — — — Net Income $ 179.7 $ 6.9 $ 186.6 Basic Earnings Per Share Continuing operations $ 0.56 $ 0.02 $ 0.58 Discontinued operations — — — Basic Earnings Per Share $ 0.56 $ 0.02 $ 0.58 Diluted Earnings Per Share Continuing operations $ 0.56 $ 0.02 $ 0.58 Discontinued operations — — — Diluted Earnings Per Share $ 0.56 $ 0.02 $ 0.58 Basic Average Common Shares Outstanding 320.3 — 320.3 Diluted Average Common Shares 322.0 0.5 322.5 (in millions, except per share amounts) As Previously Reported Effect of Change As Adjusted Three Months Ended June 30, 2016 Income from Continuing Operations before Income Taxes $ 46.1 $ — $ 46.1 Income Taxes 17.4 (0.3 ) 17.1 Income from Continuing Operations 28.7 0.3 29.0 Loss from Discontinued Operations - net of taxes (0.1 ) — (0.1 ) Net Income $ 28.6 $ 0.3 $ 28.9 Basic Earnings Per Share Continuing operations $ 0.09 $ — $ 0.09 Discontinued operations — — — Basic Earnings Per Share $ 0.09 $ — $ 0.09 Diluted Earnings Per Share Continuing operations $ 0.09 $ — $ 0.09 Discontinued operations — — — Diluted Earnings Per Share $ 0.09 $ — $ 0.09 Basic Average Common Shares Outstanding 321.7 — 321.7 Diluted Average Common Shares 322.9 0.3 323.2 (in millions, except per share amounts) As Previously Reported Effect of Change As Adjusted Six Months Ended June 30, 2016 Income from Continuing Operations before Income Taxes $ 337.7 $ — $ 337.7 Income Taxes 129.3 (7.2 ) 122.1 Income from Continuing Operations 208.4 7.2 215.6 Loss from Discontinued Operations - net of taxes (0.1 ) — (0.1 ) Net Income $ 208.3 $ 7.2 $ 215.5 Basic Earnings Per Share Continuing operations $ 0.65 $ 0.02 $ 0.67 Discontinued operations — — — Basic Earnings Per Share $ 0.65 $ 0.02 $ 0.67 Diluted Earnings Per Share Continuing operations $ 0.65 $ 0.02 $ 0.67 Discontinued operations — — — Diluted Earnings Per Share $ 0.65 $ 0.02 $ 0.67 Basic Average Common Shares Outstanding 321.0 — 321.0 Diluted Average Common Shares 322.5 0.3 322.8

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Computation Of Diluted Average Common Shares	The computation of diluted average common shares is as follows: Three Months Ended Nine Months Ended September 30, September 30, (in thousands) 2016 2015 2016 2015 Denominator Basic average common shares outstanding 322,318 318,090 321,445 317,390 Dilutive potential common shares: Shares contingently issuable under employee stock plans 228 — 146 — Shares restricted under employee stock plans 1,372 3,375 1,606 3,328 Diluted Average Common Shares 323,918 321,465 323,197 320,718

Discontinued Operations (Tables

Discontinued Operations (Tables)	9 Months Ended
	Sep. 30, 2016
Discontinued Operations and Disposal Groups [Abstract]
Schedule of Discontinued Operations	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 Income (Loss) 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 ) Income (Loss) 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 Income (Loss) 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 of transaction costs related to the Separation for the three and nine months ended September 30, 2015, respectively. (2)

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	9 Months Ended
	Sep. 30, 2016
Asset Retirement Obligation [Abstract]
Changes In Company's Liability For Asset Retirement Obligations	Changes in NiSource’s liability for asset retirement obligations for the nine months ended September 30, 2016 and 2015 are presented in the table below: (in millions) 2016 2015 Balance as of January 1, $ 254.0 $ 136.2 Accretion recorded as a regulatory asset/liability 7.7 5.9 Additions — 6.4 Settlements (2.2 ) (4.3 ) Change in estimated cash flows 12.8 (1) 37.0 (2) Balance as of September 30, $ 272.3 $ 181.2 (1) The change in estimated cash flows for 2016 is primarily attributed to changes in estimated costs for retirement of gas mains. (2) The change in estimated cash flows for 2015 primarily represents 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 17, "Other Commitments and Contingencies," for additional information on CCRs.

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	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, 2016 and December 31, 2015 : 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 September 30, 2016 Assets Risk management assets $ 1.9 $ 5.7 $ — $ 7.6 Available-for-sale securities — 137.1 — 137.1 Total $ 1.9 $ 142.8 $ — $ 144.7 Liabilities Risk management liabilities (1) $ 4.5 $ 266.5 $ 0.1 $ 271.1 Total $ 4.5 $ 266.5 $ 0.1 $ 271.1 (1) Includes $6.6 million of current risk management liabilities which are included in "Other accruals" on the Condensed Consolidated Balance Sheets (unaudited). 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, 2015 Assets Risk management assets $ 0.1 $ — $ — $ 0.1 Available-for-sale securities — 128.7 — 128.7 Total $ 0.1 $ 128.7 $ — $ 128.8 Liabilities Risk management liabilities (1) $ 14.3 $ 17.4 $ 0.2 $ 31.9 Total $ 14.3 $ 17.4 $ 0.2 $ 31.9 (1) Includes $9.3 million of current risk management liabilities which are included in "Other accruals" on the Condensed Consolidated Balance Sheets (unaudited).
Schedule of Available-For-Sale Securities	The amortized cost, gross unrealized gains and losses and fair value of available-for-sale securities at September 30, 2016 and December 31, 2015 were: September 30, 2016 (in millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities U.S. Treasury securities $ 37.4 $ 0.9 $ — $ 38.3 Corporate/Other debt securities 97.1 1.9 (0.2 ) 98.8 Total Available-for-sale securities $ 134.5 $ 2.8 $ (0.2 ) $ 137.1 December 31, 2015 (in millions) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Available-for-sale securities U.S. Treasury securities $ 33.7 $ 0.1 $ (0.3 ) $ 33.5 Corporate/Other debt securities 95.7 0.3 (0.8 ) 95.2 Total Available-for-sale securities $ 129.4 $ 0.4 $ (1.1 ) $ 128.7
Carrying Amount And Estimated Fair Values Of Financial Instruments	The carrying amount and estimated fair values of these financial instruments were as follows: (in millions) Carrying Estimated Fair Carrying Amount as of Dec. 31, 2015 Estimated Fair Value as of Dec. 31, 2015 Long-term debt (including current portion) $ 6,678.8 $ 7,639.9 $ 6,382.2 $ 6,975.7

Transfers Of Financial Assets (

Transfers Of Financial Assets (Tables)	9 Months Ended
	Sep. 30, 2016
Transfers and Servicing [Abstract]
Schedule Of Gross And Net Receivables Transferred As Well As Short-Term Borrowings Related To The Securitization Transactions	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, 2016 and December 31, 2015 for Columbia of Ohio, NIPSCO and Columbia of Pennsylvania: (in millions) September 30, 2016 December 31, 2015 Gross Receivables $ 361.6 $ 450.8 Less: Receivables not transferred 126.6 204.8 Net receivables transferred $ 235.0 $ 246.0 Short-term debt due to asset securitization $ 235.0 $ 246.0

Goodwill (Tables)

Goodwill (Tables)	9 Months Ended
	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following presents NiSource’s goodwill balance allocated by segment as of September 30, 2016 : (in millions) Gas Distribution Operations Electric Operations Corporate and Other Total Goodwill $ 1,690.7 $ — $ — $ 1,690.7

Pension And Other Postretirem37

Pension And Other Postretirement Benefits (Tables)	9 Months Ended
	Sep. 30, 2016
Pension and Other Postretirement Benefit Expense [Abstract]
Components Of The Plans' Net Periodic Benefits Cost	The following tables provide the components of the plans’ net periodic benefits cost for the three and nine months ended September 30, 2016 and 2015 : Pension Benefits Other Postretirement Benefits Three Months Ended September 30, (in millions) 2016 2015 2016 2015 Components of Net Periodic Benefit Cost Service cost $ 7.7 $ 7.9 $ 1.3 $ 1.4 Interest cost 22.4 22.8 5.5 6.2 Expected return on assets (33.2 ) (37.3 ) (4.3 ) (5.6 ) Amortization of prior service cost (credit) — 0.1 (1.2 ) (1.1 ) Recognized actuarial loss 15.3 13.8 0.8 0.7 Total Net Periodic Benefit Cost $ 12.2 $ 7.3 $ 2.1 $ 1.6 Pension Benefits Other Postretirement Benefits Nine Months Ended September 30, (in millions) 2016 2015 2016 2015 Components of Net Periodic Benefit Cost Service cost $ 23.1 $ 24.3 $ 3.7 $ 4.5 Interest cost 67.2 67.0 16.5 17.8 Expected return on assets (99.6 ) (117.7 ) (12.9 ) (15.6 ) Amortization of prior service cost (credit) (0.2 ) 0.3 (3.6 ) (3.9 ) Recognized actuarial loss 45.9 41.6 2.4 2.8 Total Net Periodic Benefit Cost $ 36.4 $ 15.5 $ 6.1 $ 5.6

Short-Term Borrowings (Tables)

Short-Term Borrowings (Tables)	9 Months Ended
	Sep. 30, 2016
Short-term Debt [Abstract]
Schedule Of Short-Term Borrowings	(in millions) September 30, December 31, Commercial Paper weighted-average interest rate of 1.07% and 1.00% at September 30, 2016 and December 31, 2015, respectively $ 824.0 $ 321.4 Accounts receivable securitization facility borrowings 235.0 246.0 Total Short-Term Borrowings $ 1,059.0 $ 567.4

Accumulated Other Comprehensi39

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 30, 2016
Other Comprehensive Income (Loss), Tax [Abstract]
Components Of Accumulated Other Comprehensive Loss	The following tables display the components of Accumulated Other Comprehensive Loss for the three and nine months ended September 30, 2016 and 2015 : Three Months Ended September 30, 2016 (in millions) Gains and Losses on 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, 2016 $ 2.0 $ (139.7 ) $ (18.6 ) $ (156.3 ) Other comprehensive loss before reclassifications (0.3 ) (22.9 ) — (23.2 ) Amounts reclassified from accumulated other comprehensive loss — 0.3 0.2 0.5 Net current-period other comprehensive income (loss) (0.3 ) (22.6 ) 0.2 (22.7 ) Balance as of September 30, 2016 $ 1.7 $ (162.3 ) $ (18.4 ) $ (179.0 ) Nine Months Ended September 30, 2016 (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, 2016 $ (0.5 ) $ (15.5 ) $ (19.1 ) $ (35.1 ) Other comprehensive income (loss) before reclassifications 2.3 (148.0 ) — (145.7 ) Amounts reclassified from accumulated other comprehensive loss (0.1 ) 1.2 0.7 1.8 Net current-period other comprehensive income (loss) 2.2 (146.8 ) 0.7 (143.9 ) Balance as of September 30, 2016 $ 1.7 $ (162.3 ) $ (18.4 ) $ (179.0 ) 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 (1) Balance as of July 1, 2015 $ — $ (20.0 ) $ (24.4 ) $ (44.4 ) Other comprehensive income (loss) before reclassifications 0.5 (0.2 ) (1.3 ) (1.0 ) Amounts reclassified from accumulated other comprehensive loss (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 (Refer to Note 4, "Discontinued Operations") — 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 (loss) before reclassifications 0.3 (0.2 ) 1.2 1.3 Amounts reclassified from accumulated other comprehensive loss (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 (Refer to Note 4, "Discontinued Operations") — 13.9 10.6 24.5 Balance as of September 30, 2015 $ 0.3 $ (5.9 ) $ (14.0 ) $ (19.6 ) (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, 2016
Segment Reporting [Abstract]
Schedule Of Operating Income Derived From Revenues And Expenses By Segment	Three Months Ended Nine Months Ended (in millions) 2016 2015 2016 2015 Revenues Gas Distribution Operations Unaffiliated $ 392.4 $ 384.6 $ 1,935.6 $ 2,349.3 Intersegment 3.1 0.1 9.6 0.4 Total 395.5 384.7 1,945.2 2,349.7 Electric Operations Unaffiliated 465.4 428.4 1,249.2 1,199.5 Intersegment 0.4 0.2 0.6 0.6 Total 465.8 428.6 1,249.8 1,200.1 Corporate and Other Unaffiliated 3.5 4.2 10.7 5.2 Intersegment 100.5 94.1 298.1 288.1 Total 104.0 98.3 308.8 293.3 Eliminations (104.0 ) (94.4 ) (308.3 ) (289.1 ) Consolidated Gross Revenues $ 861.3 $ 817.2 $ 3,195.5 $ 3,554.0 Operating Income (Loss) Gas Distribution Operations $ 4.3 $ 20.0 $ 392.7 $ 394.9 Electric Operations 112.8 98.5 251.5 214.2 Corporate and Other (3.4 ) (8.8 ) (10.9 ) (28.7 ) Consolidated Operating Income $ 113.7 $ 109.7 $ 633.3 $ 580.4

Supplemental Cash Flow Inform41

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2016
Supplemental Cash Flow Information [Abstract]
Additional Information Regarding Condensed Statements Of Consolidated Cash Flows	The following table provides additional information regarding NiSource’s Condensed Statements of Consolidated Cash Flows (unaudited) for the nine months ended September 30, 2016 and 2015 : Nine Months Ended (in millions) 2016 2015 Supplemental Disclosures of Cash Flow Information Non-cash transactions: Capital expenditures included in current liabilities $ 131.2 $ 130.7 Assets acquired under a capital lease 4.0 5.5 Schedule of interest and income taxes paid: Cash paid for interest, net of interest capitalized $ 305.5 $ 354.1 Cash paid for income taxes 5.8 20.2

Recent Accounting Pronounceme42

Recent Accounting Pronouncements (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Cumulative effect of change in accounting principle		$ 25.3
Excess Tax Benefit from Share-based Compensation, Operating Activities	$ 7.2

Recent Accounting Pronounceme43

Recent Accounting Pronouncements Schedule of Prospective Adoption of New Accounting Pronouncement (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended				6 Months Ended	9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Jun. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Income from Continuing Operations before Income Taxes, Domestic	$ 32.2	$ 46.1	$ 291.6	$ 20.6	$ 337.7	$ 369.9	$ 208.9
Income Taxes	8.5	17.1	105	5.8	122.1	130.6	74.7
Income from Continuing Operations	23.7	29	186.6	14.8	215.6	239.3	134.2
Income (Loss) from Discontinued Operations - net of taxes	3.5	(0.1)	0	(19.7)	(0.1)	3.4	108.5
Net Income	$ 27.2	$ 28.9	$ 186.6	$ (4.9)	$ 215.5	$ 242.7	$ 242.7
Basic Earnings Per Share
Continuing operations	$ 0.07	$ 0.09	$ 0.58	$ 0.05	$ 0.67	$ 0.74	$ 0.42
Discontinued operations		0	0		0
Basic Earnings Per Share	0.08	0.09	0.58	(0.02)	0.67	0.76	0.72
Diluted Earnings Per Share
Continuing operations	0.07	0.09	0.58	0.05	0.67	0.74	0.42
Discontinued operations		0	0		0
Diluted Earnings Per Share	$ 0.08	$ 0.09	$ 0.58	$ (0.02)	$ 0.67	$ 0.75	$ 0.71
Basic Average Common Shares Outstanding	322,318	321,725	320,281	318,090	321,003	321,445	317,390
Diluted Average Common Shares	323,918	323,204	322,460	321,465	322,832	323,197	320,718
Previous Accounting Guidance
Income Statement [Abstract]
Income from Continuing Operations before Income Taxes, Domestic		$ 46.1	$ 291.6		$ 337.7
Income Taxes		17.4	111.9		129.3
Income from Continuing Operations		28.7	179.7		208.4
Income (Loss) from Discontinued Operations - net of taxes		(0.1)	0		(0.1)
Net Income		$ 28.6	$ 179.7		$ 208.3
Basic Earnings Per Share
Continuing operations		$ 0.09	$ 0.56		$ 0.65
Discontinued operations		0	0		0
Basic Earnings Per Share		0.09	0.56		0.65
Diluted Earnings Per Share
Continuing operations		0.09	0.56		0.65
Discontinued operations		0	0		0
Diluted Earnings Per Share		$ 0.09	$ 0.56		$ 0.65
Basic Average Common Shares Outstanding		321,725	320,281		321,003
Diluted Average Common Shares		322,894	322,021		322,457
AccountingStandardsUpdate201609
Income Statement [Abstract]
Income from Continuing Operations before Income Taxes, Domestic		$ 0	$ 0		$ 0
Income Taxes		(0.3)	(6.9)		(7.2)
Income from Continuing Operations		0.3	6.9		7.2
Income (Loss) from Discontinued Operations - net of taxes		0	0		0
Net Income		$ 0.3	$ 6.9		$ 7.2
Basic Earnings Per Share
Continuing operations		$ 0	$ 0.02		$ 0.02
Discontinued operations		0	0		0
Basic Earnings Per Share		0	0.02		0.02
Diluted Earnings Per Share
Continuing operations		0	0.02		0.02
Discontinued operations		0	0		0
Diluted Earnings Per Share		$ 0	$ 0.02		$ 0.02
Basic Average Common Shares Outstanding		0	0		0
Diluted Average Common Shares		309	450		350

Earnings Per Share Table (Detai

Earnings Per Share Table (Details) - shares shares in Thousands	3 Months Ended				6 Months Ended	9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Jun. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Denominator
Basic Average Common Shares Outstanding	322,318	321,725	320,281	318,090	321,003	321,445	317,390
Dilutive potential common shares
Shares contingently issuable under employee stock plans	228			0		146	0
Shares restricted under stock plans	1,372			3,375		1,606	3,328
Diluted Average Common Shares	323,918	323,204	322,460	321,465	322,832	323,197	320,718

Discontinued Operations (Narrat

Discontinued Operations (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Jul. 01, 2015	May 22, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets	$ 18,067.2		$ 18,067.2		$ 17,492.5
Transaction Costs Related to Separation		$ 5.5		$ 54.4
Tax benefit ffrom favorable estimate-to-actual adjustments			3.6
Columbia Pipeline Group Operations
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
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	$ 31.9	$ 31.6	$ 107.5	$ 105.4
Columbia Pipeline Group
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					6 Months Ended	9 Months Ended
		Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015		Jun. 30, 2016	Sep. 30, 2016	Sep. 30, 2015
Net Revenues
Transportation and storage revenues					$ 0				$ 561.4
Other revenues					0				94.3
Total Sales Revenues					0				655.7
Less: Cost of sales (excluding depreciation and amortization)					0				0.2
Net Revenues					0				655.5
Operating Expenses
Operation and maintenance					5.5				374.8
Depreciation and amortization					0				66.4
Gain on sale of assets					0				(13.6)
Other taxes					0				38
Total Operating Expenses					5.5				465.6
Equity Earnings in Unconsolidated Affiliates					0				29.1
Operating Income (Loss) from Discontinued Operations					(5.5)				219
Other Income (Deductions)
Interest expense, net					0				(37.1)
Other, net					0				(7.2)
Total Other Deductions					0				(29.9)
Income (Loss) from Discontinued Operations before Income Taxes					(5.5)				189.1
Income Taxes					14.2				80.6
Income (Loss) from Discontinued Operations - net of taxes		$ 3.5	$ (0.1)	$ 0	(19.7)		$ (0.1)	$ 3.4	108.5
Columbia Pipeline Group Operations | Discontinued Operations, Spinoff
Net Revenues
Transportation and storage revenues					0				561.4
Other revenues					0				94.3
Total Sales Revenues					0				655.7
Less: Cost of sales (excluding depreciation and amortization)					0				0.2
Net Revenues					0				655.5
Operating Expenses
Operation and maintenance	[1]				5.5				374.8
Depreciation and amortization					0				66.4
Gain on sale of assets					0				(13.6)
Other taxes					0				38
Total Operating Expenses					5.5				465.6
Equity Earnings in Unconsolidated Affiliates					0				29.1
Operating Income (Loss) from Discontinued Operations					(5.5)				219
Other Income (Deductions)
Interest expense, net					0				(37.1)
Other, net					0				(7.8)
Total Other Deductions					0				(29.3)
Income (Loss) from Discontinued Operations before Income Taxes					(5.5)				189.7
Income Taxes					14.2	[2]			80.9
Income (Loss) from Discontinued Operations - net of taxes					(19.7)				108.8
Corporate and Other | Discontinued Operations, Spinoff
Net Revenues
Transportation and storage revenues					0				0
Other revenues					0				0
Total Sales Revenues					0				0
Less: Cost of sales (excluding depreciation and amortization)					0				0
Net Revenues					0				0
Operating Expenses
Operation and maintenance					0				0
Depreciation and amortization					0				0
Gain on sale of assets					0				0
Other taxes					0				0
Total Operating Expenses					0				0
Equity Earnings in Unconsolidated Affiliates					0				0
Operating Income (Loss) from Discontinued Operations					0				0
Other Income (Deductions)
Interest expense, net					0				0
Other, net					0				(0.6)
Total Other Deductions					0				(0.6)
Income (Loss) from Discontinued Operations before Income Taxes					0				(0.6)
Income Taxes					0				(0.3)
Income (Loss) from Discontinued Operations - net of taxes					$ 0				$ (0.3)
[1]	Includes approximately $5.5 million and $54.4 million of transaction costs related to the Separation for the three and nine months ended September 30, 2015, respectively.
[2]	Primarily attributable to the write-off of consolidated state income tax benefits resulting from the Separation.

Asset Retirement Obligations (C

Asset Retirement Obligations (Changes In Company's Liability For Asset Retirement Obligations) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016		Sep. 30, 2015
Asset Retirement Obligation [Abstract]
Beginning Balance	$ 254		$ 136.2
Accretion recorded as a regulatory asset/liability	7.7		5.9
Additions	0		6.4
Settlements	(2.2)		(4.3)
Change in estimated cash flows	12.8	[1]	37	[2]
Ending Balance	$ 272.3		$ 181.2
[1]	The change in estimated cash flows for 2016 is primarily attributed to changes in estimated costs for retirement of gas mains.
[2]	The change in estimated cash flows for 2015 primarily represents 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 17, "Other Commitments and Contingencies," for additional information on CCRs.

Regulatory Matters (Narrative)

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

Oct. 31, 2016

Oct. 27, 2016

Oct. 20, 2016

Sep. 28, 2016

Aug. 26, 2016

Jul. 27, 2016

Jun. 30, 2016

May 27, 2016

May 01, 2016

Apr. 29, 2016

Apr. 15, 2016

Mar. 18, 2016

Mar. 16, 2016

Mar. 11, 2016

Feb. 26, 2016

Feb. 19, 2016

Jan. 29, 2016

Dec. 31, 2015

Oct. 30, 2015

Oct. 01, 2015

Dec. 17, 2014

Nov. 12, 2013

Jul. 19, 2013

Sep. 30, 2016

Sep. 30, 2016

Sep. 30, 2015

Dec. 31, 2015

Aug. 31, 2016

Jun. 22, 2016

Apr. 20, 2016

Mar. 24, 2016

Regulatory Matters [Line Items]

Seven Year Plan of Eligible Investments, Length of Plan

seven-year

New Seven Year plan of Eligible Investments, Length of Plan

seven-year

Increase (Decrease) in Regulatory Assets and Liabilities

$ 202.2

$ (259.6)

Columbia Of Ohio

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 25.9

Requested Regulatory Deferral

$ 25

Approved Regulatory Deferral

$ 25

$ 15

Columbia Of Massachusetts | 2016 GSEP

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Cumulative Amount

$ 9

Public Utilities, Requested Rate Increase (Decrease), Revised Cumulative Amount

$ 8.2

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 6.4

Columbia Of Massachusetts | CMA Off-peak RDAF

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 3.4

Columbia Of Massachusetts | CMA Off-Peak Local Distribution Adjustment Factor (LDAF)

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 42

Columbia Of Maryland

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 6.5

Public Utilities, Requested Rate Increase (Decrease), Amended, Amount

$ 3.7

Columbia Of Virginia

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 37

Columbia Of Kentucky

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 25.4

Columbia Of Pennsylvania

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 55.3

Capital Investment Program Amount

$ 197

Capital Investment Program Amount year 2

220

Capital Investment Program Amount year 3

$ 265

NIPSCO

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 45.5

Amount of public utility's requested rate increase (decrease) with regulatory agency, before riders

$ 72.5

$ 126.6

New Seven year Plan of Eligible Investments Under TDSIC, Amount of Investment

$ 1,300

$ 1,300

New Seven year Plan of Eligible Investments Under TDSIC, Amount of Investment, Updated

$ 1,250

Public Utilities, Approved Return on Equity, Percentage

12.38%

Public Utilities, Requested Return on Equity, Percentage, Amended

10.32%

9.70%

10.82%

Liability associated with Public Utilities, requested amendment to ROE

$ 5.3

$ 5.3

Increase (Decrease) in Regulatory Assets and Liabilities

$ 7.8

NIPSCO | TDSIC 3 Gas

Regulatory Matters [Line Items]

Regulatory Net Capital Expenditures Included In Filing

$ 145.7

Seven Year Plan of Eligible Investments Under TDSIC

$ 800

NIPSCO | TDSIC 5 Gas

Regulatory Matters [Line Items]

Regulatory Net Capital Expenditures Included In Filing

$ 211.6

NIPSCO | TDSIC 5 Gas

Regulatory Matters [Line Items]

Seven Year Plan of Eligible Investments Under TDSIC

$ 824

NIPSCO | ECR 27

Regulatory Matters [Line Items]

Regulatory Net Capital Expenditures Included In Filing

$ 800.7

NIPSCO | ECR 28

Regulatory Matters [Line Items]

Regulatory Net Capital Expenditures Included In Filing

$ 267

Subsequent Event | Columbia Of Massachusetts | 2017 GSEP

Regulatory Matters [Line Items]

Public Utilities, Requested Rate Increase (Decrease), Cumulative Amount

$ 16.8

Public Utilities, Requested Rate Increase (Decrease), Amount

$ 8.1

Subsequent Event | Columbia Of Kentucky

Regulatory Matters [Line Items]

Public Utilities, Approved Rate Increase (Decrease), Amount

$ 13.4

Subsequent Event | Columbia Of Pennsylvania

Regulatory Matters [Line Items]

Public Utilities, Approved Rate Increase (Decrease), Amount

$ 35

Risk Management Activities (Nar

Risk Management Activities (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Jun. 24, 2016	Dec. 31, 2015
Derivative [Line Items]
Notional Amount of Forward-Starting Interest rate Swap Agreements	$ 1,500		$ 500
Swap Forecasted Debt Issuance	2,018
Derivative, Notional Amount, Current	$ 250
Risk management assets
Derivative [Line Items]
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net	0	$ 0
Derivative Liability, Fair Value, Gross Liability	256.8			$ 17.4
Price Risk Cash Flow Hedge Unrealized Gain (Loss) to be Reclassified During Next 12 Months	$ 0

Fair Value (Narrative) (Details

Fair Value (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Fair Value Disclosure [Line Items]
Derivative Liability, Current	$ 6.6		$ 6.6		$ 9.3
Transfers between Fair Value Hierarchies			0	0
Material Level 3 Changes			$ 0	$ 0
Fair Value, Assets and Liabilities Measured on a Non-Recurring Basis			0	0
U.S. Treasury securities
Fair Value Disclosure [Line Items]
Available-for-sale Securities, Realized Gain (Loss)	0	$ 0.1	$ 0	$ 0.2
Available-for-sale Securities, Maturities, Next Twelve Months, Fair Value	2.8		2.8
Corporate/Other Debt Securities
Fair Value Disclosure [Line Items]
Available-for-sale Securities, Realized Gain (Loss)	0	$ 0.2	0.1	$ 0.3
Available-for-sale Securities, Maturities, Next Twelve Months, Fair Value	$ 15.5		$ 15.5

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, 2016		Dec. 31, 2015
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available-for-sale securities	$ 137.1		$ 128.7
Fair value assets measured on recurring basis, total	144.7		128.8
Fair value liabilities measured on recurring basis, total	271.1		31.9
Fair Value, Inputs, Level 1
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value assets measured on recurring basis, total	1.9		0.1
Fair value liabilities measured on recurring basis, total	4.5		14.3
Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value assets measured on recurring basis, total	142.8		128.7
Fair value liabilities measured on recurring basis, total	266.5		17.4
Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value assets measured on recurring basis, total	0		0
Fair value liabilities measured on recurring basis, total	0.1		0.2
Available-for-sale Securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available-for-sale securities	137.1		128.7
Available-for-sale Securities | Fair Value, Inputs, Level 1
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available-for-sale securities	0		0
Available-for-sale Securities | Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available-for-sale securities	137.1		128.7
Available-for-sale Securities | Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available-for-sale securities	0		0
Risk management assets
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value assets measured on recurring basis, derivative financial instruments	7.6		0.1
Fair value liabilities measured on recurring basis, derivative financial instruments	271.1	[1]	31.9	[2]
Risk management assets | Fair Value, Inputs, Level 1
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value assets measured on recurring basis, derivative financial instruments	1.9		0.1
Fair value liabilities measured on recurring basis, derivative financial instruments	4.5	[1]	14.3	[2]
Risk management assets | Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Fair value assets measured on recurring basis, derivative financial instruments	5.7		0
Fair value liabilities measured on recurring basis, derivative financial instruments	266.5	[1]	17.4	[2]
Risk management assets | Significant Unobservable Inputs (Level 3)
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	$ 0.1	[1]	$ 0.2	[2]
[1]	Includes $6.6 million of current risk management liabilities which are included in "Other accruals" on the Condensed Consolidated Balance Sheets (unaudited).
[2]	Includes $9.3 million of current risk management liabilities which are included in "Other accruals" on the Condensed Consolidated Balance Sheets (unaudited).

Fair Value (Available-For-Sale

Fair Value (Available-For-Sale Securities) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Fair Value Disclosure [Line Items]
Amortized Cost	$ 134.5	$ 129.4
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	2.8	0.4
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(0.2)	(1.1)
Fair Value	137.1	128.7
U.S. Treasury securities
Fair Value Disclosure [Line Items]
Amortized Cost	37.4	33.7
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	0.9	0.1
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	(0.3)
Fair Value	38.3	33.5
Corporate/Other Debt Securities
Fair Value Disclosure [Line Items]
Amortized Cost	97.1	95.7
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1.9	0.3
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(0.2)	(0.8)
Fair Value	$ 98.8	$ 95.2

Fair Value (Carrying Amount And

Fair Value (Carrying Amount And Estimated Fair Values Of Financial Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Long-term Debt (including current portion), Gross	$ 6,678.8	$ 6,382.2
Long-term debt (including current portion), Estimated Fair Value	$ 7,639.9	$ 6,975.7

Transfers Of Financial Assets54

Transfers Of Financial Assets (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Accounts receivable securitization facility borrowings	$ 235		$ 235		$ 246
Net receivables transferred	235		235		$ 246
Cash From Financing Activities Related To The Change In Short-Term Borrowings Due To The Securitization Transactions			(11)	$ (177.1)
Securitization Transaction Fees	0.4	$ 0.5	$ 1.6	$ 1.9
Columbia Gas Of Ohio Receivables Corporation
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Trade Receivable Agreement Expiration Date			Oct. 13, 2017
Net receivables transferred	75		$ 75
NIPSCO Accounts Receivable Corporation
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Trade Receivable Agreement Expiration Date			Aug. 23, 2017
Net receivables transferred	150		$ 150
Columbia Gas Of Pennsylvania Receivables Corporation
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Trade Receivable Agreement Expiration Date			Mar. 8, 2017
Net receivables transferred	10		$ 10
Maximum | Accounts Receivable Program
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Accounts receivable securitization facility borrowings	515		515
Maximum | Columbia Gas Of Ohio Receivables Corporation
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Trade receivables, seasonal program maximum	240		240
Maximum | NIPSCO Accounts Receivable Corporation
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Trade receivables, seasonal program maximum	200		200
Maximum | Columbia Gas Of Pennsylvania Receivables Corporation
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Trade receivables, seasonal program maximum	$ 75		$ 75

Transfers Of Financial Assets55

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, 2016	Dec. 31, 2015
Gross Receivables	$ 361.6	$ 450.8
Less: Receivables not transferred	126.6	204.8
Net receivables transferred	235	246
Accounts receivable securitization facility borrowings	$ 235	$ 246

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Goodwill [Line Items]
Goodwill	$ 1,690.7	$ 1,690.7
Gas Distribution Operations
Goodwill [Line Items]
Goodwill	1,690.7
Electric Operations
Goodwill [Line Items]
Goodwill	0
Corporate and Other
Goodwill [Line Items]
Goodwill	$ 0

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Effective income tax rates	26.40%	28.20%	35.30%	35.80%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate			35.00%
Increase (Decrease) in Effective Tax Rate	(1.80%)		(0.50%)
Changes to Liability for Uncertain Tax Positions			$ 0

Pension And Other Postretirem58

Pension And Other Postretirement Benefits (Narrative) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 2.7
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 18.6

Pension And Other Postretirem59

Pension And Other Postretirement Benefits (Components Of The Plans' Net Periodic Benefits Cost) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service Cost	$ 7.7	$ 7.9	$ 23.1	$ 24.3
Interest cost	22.4	22.8	67.2	67
Expected return on assets	(33.2)	(37.3)	(99.6)	(117.7)
Amortization of prior service cost (credit)	0	0.1	(0.2)	0.3
Recognized actuarial loss	15.3	13.8	45.9	41.6
Total Net Periodic Benefits Cost	12.2	7.3	36.4	15.5
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service Cost	1.3	1.4	3.7	4.5
Interest cost	5.5	6.2	16.5	17.8
Expected return on assets	(4.3)	(5.6)	(12.9)	(15.6)
Amortization of prior service cost (credit)	(1.2)	(1.1)	(3.6)	(3.9)
Recognized actuarial loss	0.8	0.7	2.4	2.8
Total Net Periodic Benefits Cost	$ 2.1	$ 1.6	$ 6.1	$ 5.6

Variable Interests and Variab60

Variable Interests and Variable Interest Entities (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Variable Interest Entities And Equity Investments [Abstract]
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 0
Payments made to Pure Air	$ 16	$ 16.5

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Mar. 15, 2016
Debt Instrument [Line Items]
Swap Forecasted Debt Issuance	2,018
Nisource Finance
Debt Instrument [Line Items]
Subsidiary Ownership Percent	100.00%
Nisource Finance | Interest Rate Swap
Debt Instrument [Line Items]
Notional Amount of Forward-Starting Interest rate Swap Agreements	$ 500
Loss on Fair Value Hedge Ineffectiveness	0
Nisource Finance | Variable Rate Term Loan Due 2019
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500
Debt Instrument, Maturity Date	Mar. 29, 2019
Amount of debt outstanding	$ 500
Nisource Finance | Senior Notes
Debt Instrument [Line Items]
Debt Instrument, Repurchase Amount		$ 201.5
Debt Instrument, Interest Rate, Stated Percentage		10.75%

Short-Term Borrowings (Narrativ

Short-Term Borrowings (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Short-term Debt [Line Items]
Commercial paper outstanding	$ 824	$ 321.4
Accounts receivable securitization facility borrowings	235	246
Short-term borrowings	1,059	567.4
Revolving Credit Facility
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,500
Line of Credit Facility, Amount Outstanding	$ 0
Revolving Credit Facility, Expiration Date	Jul. 1, 2020
Commercial Paper
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,500
Commercial paper outstanding	824	321.4
Standby Letters of Credit
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, 2016	Dec. 31, 2015
Short-term Debt [Line Items]
Commercial paper outstanding	$ 824	$ 321.4
Accounts receivable securitization facility borrowings	235	246
Total short-term borrowings	1,059	567.4
Commercial Paper
Short-term Debt [Line Items]
Commercial paper outstanding	$ 824	$ 321.4
Short-term Debt, Weighted Average Interest Rate	1.07%	1.00%

Share-Based Compensation (Narra

Share-Based Compensation (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	May 12, 2015
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	4,991,665		4,991,665
Allocated Share-based Compensation Expense	$ 3.6	$ 4.2	$ 11.1	$ 15.1
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	1.4	1.5	4.3	5.4
Excess Tax Benefit from Share-based Compensation, Operating Activities			7.2
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	17.6		$ 17.6
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			1 year 11 months
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay			3.00%
Defined Contribution Plan, Cost Recognized	$ 8.3	$ 4.8	$ 22.5	$ 19
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period			3 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			62,031
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value			$ 1.3
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	1,670,941		1,670,941
Performance Shares
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			647,305
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value			$ 12.6
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	647,305		647,305
AccountingStandardsUpdate201609
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Excess Tax Benefit from Share-based Compensation, Operating Activities	$ 0

Other Commitments And Conting65

Other Commitments And Contingencies (Narrative) (Details) $ in Millions	Apr. 17, 2015USD ($)	Sep. 30, 2016USD ($)	Dec. 31, 2015USD ($)
Other Commitments And Contingencies [Line Items]
Proposed Pipeline Safety Rule, time period for investigation and repair/replace activity on facilities		15 years
Recorded reserves to cover environmental remediation at various sites		$ 116.9	$ 123.2
Number of countries agreeing to limit GHGs		194
Proposed reduction in GHG levels		26-28%
Estimated Cost of Compliance with Effluent Limitations Guidelines		$ 170
Estimated Cost of Compliance with Coal Combustion Residuals	$ 230
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		$ 108.3	$ 110.4
Reasonably possible remediation costs variance from reserve		25
NIPSCO
Other Commitments And Contingencies [Line Items]
Upgrade Sponsors Liability related to Portion Collected for Taxes on TUA		8.6
Gain (Loss) on Contract Termination		16
Letters Of Credit
Other Commitments And Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted		$ 14.7
Maximum
Other Commitments And Contingencies [Line Items]
Ozone Level		75 ppb
Estimated Cost of Compliance with Clean Water Act, minimum		$ 35
Maximum | NIPSCO
Other Commitments And Contingencies [Line Items]
Severance Costs		15
Total Severance and Contract Termination Cost		$ 31
Minimum
Other Commitments And Contingencies [Line Items]
Ozone Level		70 ppb
Estimated Cost of Compliance with Clean Water Act, minimum		$ 0
Minimum | NIPSCO
Other Commitments And Contingencies [Line Items]
Cost to Maintain and Operate Current Fleet of Coal-Fired Generating Units		1,000
Severance Costs		10
Total Severance and Contract Termination Cost		$ 26

Accumulated Other Comprehensi66

Accumulated Other Comprehensive Loss (Components Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (156.3)	$ (44.4)	$ (35.1)	$ (50.6)
Other Comprehensive Income before reclassifications	(23.2)	(1)	(145.7)	1.3
Amounts reclassified from accumulated other comprehensive loss	0.5	1.3	1.8	3.2
Net current-period other comprehensive income (loss)	(22.7)	0.3	(143.9)	4.5
Allocation of AOCI to Noncontrolling Interest				2
Distribution of CPG to shareholders (Refer to Note 4, Discontinued Operations)		24.5		24.5
Ending Balance	(179)	(19.6)	(179)	(19.6)
Gains and Losses on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	2	0	(0.5)	0.3
Other Comprehensive Income before reclassifications	(0.3)	0.5	2.3	0.3
Amounts reclassified from accumulated other comprehensive loss	0	(0.2)	(0.1)	(0.3)
Net current-period other comprehensive income (loss)	(0.3)	0.3	2.2	0
Allocation of AOCI to Noncontrolling Interest				0
Distribution of CPG to shareholders (Refer to Note 4, Discontinued Operations)		0		0
Ending Balance	1.7	0.3	1.7	0.3
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(139.7)	(20)	(15.5)	(23.6)
Other Comprehensive Income before reclassifications	(22.9)	(0.2)	(148)	(0.2)
Amounts reclassified from accumulated other comprehensive loss	0.3	0.4	1.2	2
Net current-period other comprehensive income (loss)	(22.6)	0.2	(146.8)	1.8
Allocation of AOCI to Noncontrolling Interest				2
Distribution of CPG to shareholders (Refer to Note 4, Discontinued Operations)		13.9		13.9
Ending Balance	(162.3)	(5.9)	(162.3)	(5.9)
Pension and OPEB Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(18.6)	(24.4)	(19.1)	(27.3)
Other Comprehensive Income before reclassifications	0	(1.3)	0	1.2
Amounts reclassified from accumulated other comprehensive loss	0.2	1.1	0.7	1.5
Net current-period other comprehensive income (loss)	0.2	(0.2)	0.7	2.7
Allocation of AOCI to Noncontrolling Interest				0
Distribution of CPG to shareholders (Refer to Note 4, Discontinued Operations)		10.6		10.6
Ending Balance	$ (18.4)	$ (14)	$ (18.4)	$ (14)

Business Segment Information (N

Business Segment Information (Narrative) (Details)	9 Months Ended
	Sep. 30, 2016
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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues	$ 861.3	$ 817.2	$ 3,195.5	$ 3,554
Consolidated Operating Income (Loss)	113.7	109.7	633.3	580.4
Gas Distribution Operations
Segment Reporting Information [Line Items]
Revenues	395.5	384.7	1,945.2	2,349.7
Consolidated Operating Income (Loss)	4.3	20	392.7	394.9
Gas Distribution Operations | Unaffiliated
Segment Reporting Information [Line Items]
Revenues	392.4	384.6	1,935.6	2,349.3
Gas Distribution Operations | Intersegment
Segment Reporting Information [Line Items]
Revenues	3.1	0.1	9.6	0.4
Electric Operations
Segment Reporting Information [Line Items]
Revenues	465.8	428.6	1,249.8	1,200.1
Consolidated Operating Income (Loss)	112.8	98.5	251.5	214.2
Electric Operations | Unaffiliated
Segment Reporting Information [Line Items]
Revenues	465.4	428.4	1,249.2	1,199.5
Electric Operations | Intersegment
Segment Reporting Information [Line Items]
Revenues	0.4	0.2	0.6	0.6
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	104	98.3	308.8	293.3
Consolidated Operating Income (Loss)	(3.4)	(8.8)	(10.9)	(28.7)
Corporate and Other | Unaffiliated
Segment Reporting Information [Line Items]
Revenues	3.5	4.2	10.7	5.2
Corporate and Other | Intersegment
Segment Reporting Information [Line Items]
Revenues	100.5	94.1	298.1	288.1
Eliminations
Segment Reporting Information [Line Items]
Revenues	$ (104)	$ (94.4)	$ (308.3)	$ (289.1)

Supplemental Cash Flow Inform69

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Non-cash transactions:
Capital expenditures included in current liabilities	$ 131.2	$ 130.7
Assets acquired under a capital lease	4	5.5
Schedule of interest and income taxes paid:
Cash paid for interest, net of interest capitalized	305.5	354.1
Cash paid for income taxes	$ 5.8	$ 20.2