XML 28 R18.htm IDEA: XBRL DOCUMENT
v3.23.1

Gas in Storage | 3 Months Ended
--- | ---
Mar. 31, 2023
Gas in Storage [Abstract] |
Gas in Storage | We use both the LIFO inventory methodology and the weighted-average cost methodology to value natural gas in storage. Natural gas storage injections are priced at the average of the costs of natural gas supply purchased during the year. For interim periods, the difference in the cost of replacing the current portion of stored gas inventory compared to the amount stated on a LIFO basis is recorded within the Condensed Consolidated Balance Sheets (unaudited). Due to seasonality requirements, we expect interim variances in LIFO layers to be replenished by year end. The LIFO basis exceeded the cost of replacing the current portion of stored gas by $22.3 million and zero as of March 31, 2023 and December 31, 2022, respectively, for certain gas distribution companies recorded within "Prepayments and other" on the Condensed Consolidated Balance Sheets (unaudited).

X
- Definition Gas in Storage [Abstract] + References No definition available. + Details
Name: | nix_GasinStorageAbstract
Namespace Prefix: | nix_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The entire disclosure for inventory. Includes, but is not limited to, the basis of stating inventory, the method of determining inventory cost, the classes of inventory, and the nature of the cost elements included in inventory. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 330 -URI https://asc.fasb.org/topic&trid=2126998 + Details
Name: | us-gaap_InventoryDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration