Document and Entity Information
| Document and Entity Information | Jul. 15, 2020 |
| Document And Entity Information [Line Items] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001111711 |
| Document Type | 8-K |
| Document Period End Date | Jul. 15, 2020 |
| Entity Registrant Name | NiSource Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-16189 |
| Entity Tax Identification Number | 35-2108964 |
| Entity Address, Address Line One | 801 East 86th Avenue |
| Entity Address, City or Town | Merrillville |
| Entity Address, State or Province | IN |
| Entity Address, Postal Zip Code | 46410 |
| City Area Code | (877) |
| Local Phone Number | 647-5990 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common Stock, par value $0.01 per share |
| Trading Symbol | NI |
| Security Exchange Name | NYSE |
| Series B Preferred Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Depositary Shares, each representing a 1/1,000th ownership interest in a share of 6.50% Series B Fixed-Rate Reset Cumulative Redeemable Perpetual |
| Trading Symbol | NI PR B |
| Security Exchange Name | NYSE |