Regulatory Matters	6 Months Ended
Jun. 30, 2014
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 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 October 3, 2013, NIPSCO filed its gas TDSIC seven-year plan of eligible investments for a total of approximately $710 million with the IURC. On April 30, 2014, the IURC issued an order approving NIPSCO’s gas TDSIC seven-year plan. NIPSCO anticipates filing its request with the IURC for ratemaking and accounting relief associated with the eligible investments in the third quarter of 2014. On May 29, 2014, the NIPSCO Industrial Group filed a Notice of Appeal with the Indiana Court of Appeals in response to the IURC's April 30, 2014 ruling. On November 25, 2013, Columbia of Ohio filed a Notice of Intent to file an application to adjust rates associated with its IRP and DSM Riders. Columbia of Ohio filed its Application on February 28, 2014, requesting authority to increase revenues by approximately $25.5 million. The parties have settled all issues, and on April 7, 2014 filed a stipulation providing for a revenue increase of approximately $25.5 million. On April 23, 2014, Columbia of Ohio received approval of its annual infrastructure replacement and demand-side management rider request from the PUCO. New rates became effective April 30, 2014. On April 16, 2013, Columbia of Massachusetts submitted a filing with the Massachusetts DPU requesting an annual revenue requirement increase of $30.1 million. Pursuant to the procedural schedule for this case, on September 3, 2013, Columbia of Massachusetts filed its updated revenue requirement of $29.5 million and on October 16, 2013, filed an updated cost of service for $30.0 million. A final revenue requirement update of $29.9 million was filed on December 16, 2013. On February 28, 2014, the Massachusetts DPU issued an order granting an annual revenue requirement increase of $19.3 million effective March 1, 2014, and the compliance filing associated with the order has been approved. Columbia of Massachusetts currently has two Motions for Reconsideration and Clarification pending before the Massachusetts DPU with regard to specific findings in the order. On September 16, 2013, Columbia of Massachusetts filed its Peak Period GAF for the period November 1, 2013 through April 30 2014, and its Peak Period 2012-2013 GAF Reconciliation. On January 17, 2014, Columbia of Massachusetts filed a revision to the GAF effective February 1, 2014, and on February 18, 2014, Columbia of Massachusetts filed its second revision to the GAF effective March 1, 2014, to eliminate Columbia of Massachusetts’s projected Peak Period under-collection of $50.0 million. On February 28, 2014, the Massachusetts DPU approved a revised GAF subject to further review and reconciliation to recover approximately $25 million of the anticipated under-collection and defer recovery of the remaining $25 million to November 2014 through April 2015, and thus, this deferred amount will be incorporated into the proposed GAF to be submitted in September 2014 in Columbia of Massachusetts’s 2014-2015 Peak Period GAF filing. On March 21, 2014, Columbia of Pennsylvania filed a base rate case with the Pennsylvania PUC, seeking a revenue increase of approximately $54.1 million annually. The case is driven by Columbia of Pennsylvania’s capital investment program which exceeds $180 million in both 2014 and 2015 as well as new pipeline safety-related operation and maintenance expenditures. Columbia of Pennsylvania seeks Pennsylvania PUC approval to implement additional rates to recover costs that are projected to be incurred after the implementation of those new rates, as authorized by the Pennsylvania General Assembly with the passage of Act 11 of 2012. Columbia of Pennsylvania's filing seeks to implement rates in December 2014 under which Columbia of Pennsylvania would immediately begin to recover costs that are projected for the twelve-month period ending December 31, 2015. The case is currently in discovery, and a final order from the Pennsylvania PUC is expected in the fourth quarter of 2014. On April 30, 2014, Columbia of Virginia filed a base rate case with the VSCC seeking an annual revenue increase of $31.8 million, which includes $6.9 million in annual revenues currently collected as a separate infrastructure replacement rider on customers’ bills under the Virginia SAVE Plan Act. The SAVE rider will be reset to zero and these revenues will be moved into non-gas base rates, resulting in a proposed net revenue increase of $24.9 million per year. Columbia of Virginia also seeks to recover costs related to its implementation of pipeline safety programs and forward looking adjustments to its capital investments and changes in operating costs projected to occur during the rate year ending September 30, 2015. In addition, Columbia of Virginia is proposing a change from volumetric based (Mcf) billing to thermal based (Btu) billing. The VSCC issued a procedural order in the case on May 28, 2014 which scheduled the case for hearing on December 9, 2014. New rates are subject to refund and are scheduled to become effective October 1, 2014. Cost Recovery and Trackers. 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 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, gas energy efficiency programs, and bad debt recovery mechanisms. Comparability of Gas Distribution Operations line item operating results is impacted by regulatory trackers that allow for the recovery in rates of certain costs such as bad debt expenses. Increases in the expenses that are subject to trackers result in a corresponding increase in net revenues and therefore have essentially no impact on total operating income results. Certain of the NiSource distribution companies have completed rate proceedings involving infrastructure replacement or are embarking upon regulatory initiatives to replace significant portions of their operating systems that are nearing the end of their useful lives. Each LDC's approach to cost recovery may be unique, given the different laws, regulations and precedent that exist in each jurisdiction. Columbia Pipeline Group Operations Regulatory Matters Significant Rate Developments. On January 30, 2014, Columbia Transmission received FERC approval of its December 2013 filing to recover costs associated with the first year of its comprehensive system modernization program. During 2013, Columbia Transmission completed more than 30 individual projects representing a total investment of about $300 million. The program includes replacement of aging pipeline and compressor facilities, enhancements to system inspection capabilities, and improvements in real-time analytics and control systems. Recovery of the 2013 investments began on February 1, 2014. The second year of the program includes planned modernization investments of approximately $300 million. Columbia Transmission and its customers have agreed to the initial five years of the comprehensive modernization program, with an opportunity to mutually extend the agreement. Cost Recovery Trackers. A significant portion of the regulated transmission and storage companies' revenue is related to the recovery of their operating costs, the review and recovery of which occurs via standard regulatory proceedings with the FERC under section 4 of the Natural Gas Act. However, certain operating costs of the NiSource regulated transmission and storage companies are significant and recurring in nature, such as fuel for compression and lost and unaccounted for gas. The FERC allows for the recovery of such costs via cost tracking mechanisms. These tracking mechanisms allow the transmission and storage companies' rates to fluctuate in response to changes in certain operating costs or conditions as they occur to facilitate the timely recovery of its costs incurred. The tracking mechanisms involve a rate adjustment that is filed at a predetermined frequency, typically annually, with the FERC and is subject to regulatory review before new rates go into effect. Other such costs under regulatory tracking mechanisms include third-party pipeline transportation, electric compression, certain environmental, and certain operational purchases and sales of natural gas. Electric Operations Regulatory Matters Significant Rate Developments. On July 19, 2013, NIPSCO filed its electric TDSIC, further discussed above, with the IURC. The filing included the seven-year plan of eligible investments for a total of approximately $1.1 billion with the majority of the spend occurring in years 2016 through 2020. On February 17, 2014, the IURC issued an order approving NIPSCO’s seven-year plan of eligible investments. The Order also granted NIPSCO ratemaking relief associated with the eligible investments through a rate adjustment mechanism. NIPSCO anticipates filing its first semi-annual tracker petition in the third quarter of 2014. On March 10, 2014, the OUCC filed a Petition for Reconsideration with the IURC, and the IURC denied that Petition for Reconsideration on May 7, 2014. In addition, the NIPSCO Industrial Group and the OUCC have filed Notices of Appeal with the Indiana Court of Appeals in response to the IURC's ruling, which are still pending. On November 12, 2013, several industrial customers, including INDIEC, filed a complaint at the FERC regarding the 12.38% base ROE used to set the MISO Transmission Owners' transmission rates and requesting a reduction in the base ROE to 9.15%. The complaint further requests that FERC limit the capital structure of MISO Transmission Owners to no more than 50% common equity for ratemaking purposes and that FERC eliminate incentive adders for membership in a RTO. NIPSCO joined in an answer defending the 12.38% base ROE and motion to dismiss the complaint filed on behalf of a group of MISO Transmission Owners on January 6, 2014. NIPSCO is unable to estimate the impact of this complaint or the timing of any potential impact at this time. Cost Recovery and Trackers. A significant portion of NIPSCO's revenue is related to the recovery of fuel costs to generate power and purchased power. These costs are recovered through a FAC, a standard, quarterly, “summary” regulatory proceeding in Indiana. Certain operating costs of the Electric Operations are significant, recurring in nature, and generally outside the control of NIPSCO. The IURC allows for recovery of such costs via cost tracking mechanisms. Such tracking mechanisms allow for abbreviated regulatory proceedings in order for NIPSCO to implement charges and recover appropriate costs. Tracking mechanisms allow for more timely recovery of such costs as compared with more traditional cost recovery mechanisms. Examples of such mechanisms include electric energy efficiency programs, MISO non-fuel costs and revenues, federally mandated costs, resource capacity charges, and environmental related costs. NIPSCO has approval from the IURC to recover certain environmental related costs through an ECT. Under the ECT, NIPSCO is permitted to recover (1) AFUDC and a return on the capital investment expended by NIPSCO to implement environmental compliance plan projects through an ECRM and (2) related operation and maintenance and depreciation expenses once the environmental facilities become operational through an EERM. On April 30, 2014, the IURC issued an order on ECR-23 approving NIPSCO’s request to begin earning a return on $583.5 million of net capital expenditures.

Regulatory Matters

Gas Distribution Operations Regulatory Matters

Significant Rate Developments. On April 30, 2013, Indiana Governor Pence signed Senate Enrolled Act 560 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 October 3, 2013, NIPSCO filed its gas TDSIC seven-year plan of eligible investments for a total of approximately $710 million with the IURC. On April 30, 2014, the IURC issued an order approving NIPSCO’s gas TDSIC seven-year plan. NIPSCO anticipates filing its request with the IURC for ratemaking and accounting relief associated with the eligible investments in the third quarter of 2014. On May 29, 2014, the NIPSCO Industrial Group filed a Notice of Appeal with the Indiana Court of Appeals in response to the IURC's April 30, 2014 ruling.

On November 25, 2013, Columbia of Ohio filed a Notice of Intent to file an application to adjust rates associated with its IRP and DSM Riders. Columbia of Ohio filed its Application on February 28, 2014, requesting authority to increase revenues by approximately $25.5 million. The parties have settled all issues, and on April 7, 2014 filed a stipulation providing for a revenue increase of approximately $25.5 million. On April 23, 2014, Columbia of Ohio received approval of its annual infrastructure replacement and demand-side management rider request from the PUCO. New rates became effective April 30, 2014.

On April 16, 2013, Columbia of Massachusetts submitted a filing with the Massachusetts DPU requesting an annual revenue requirement increase of $30.1 million. Pursuant to the procedural schedule for this case, on September 3, 2013, Columbia of Massachusetts filed its updated revenue requirement of $29.5 million and on October 16, 2013, filed an updated cost of service for $30.0 million. A final revenue requirement update of $29.9 million was filed on December 16, 2013. On February 28, 2014, the Massachusetts DPU issued an order granting an annual revenue requirement increase of $19.3 million effective March 1, 2014, and the compliance filing associated with the order has been approved. Columbia of Massachusetts currently has two Motions for Reconsideration and Clarification pending before the Massachusetts DPU with regard to specific findings in the order.

On September 16, 2013, Columbia of Massachusetts filed its Peak Period GAF for the period November 1, 2013 through April 30 2014, and its Peak Period 2012-2013 GAF Reconciliation. On January 17, 2014, Columbia of Massachusetts filed a revision to the GAF effective February 1, 2014, and on February 18, 2014, Columbia of Massachusetts filed its second revision to the GAF effective March 1, 2014, to eliminate Columbia of Massachusetts’s projected Peak Period under-collection of $50.0 million. On February 28, 2014, the Massachusetts DPU approved a revised GAF subject to further review and reconciliation to recover approximately $25 million of the anticipated under-collection and defer recovery of the remaining $25 million to November 2014 through April 2015, and thus, this deferred amount will be incorporated into the proposed GAF to be submitted in September 2014 in Columbia of Massachusetts’s 2014-2015 Peak Period GAF filing.

On March 21, 2014, Columbia of Pennsylvania filed a base rate case with the Pennsylvania PUC, seeking a revenue increase of approximately $54.1 million annually. The case is driven by Columbia of Pennsylvania’s capital investment program which exceeds $180 million in both 2014 and 2015 as well as new pipeline safety-related operation and maintenance expenditures. Columbia of Pennsylvania seeks Pennsylvania PUC approval to implement additional rates to recover costs that are projected to be incurred after the implementation of those new rates, as authorized by the Pennsylvania General Assembly with the passage of Act 11 of 2012. Columbia of Pennsylvania's filing seeks to implement rates in December 2014 under which Columbia of Pennsylvania would immediately begin to recover costs that are projected for the twelve-month period ending December 31, 2015. The case is currently in discovery, and a final order from the Pennsylvania PUC is expected in the fourth quarter of 2014.

On April 30, 2014, Columbia of Virginia filed a base rate case with the VSCC seeking an annual revenue increase of $31.8 million, which includes $6.9 million in annual revenues currently collected as a separate infrastructure replacement rider on customers’ bills under the Virginia SAVE Plan Act. The SAVE rider will be reset to zero and these revenues will be moved into non-gas base rates, resulting in a proposed net revenue increase of $24.9 million per year. Columbia of Virginia also seeks to recover costs related to its implementation of pipeline safety programs and forward looking adjustments to its capital investments and changes in operating costs projected to occur during the rate year ending September 30, 2015. In addition, Columbia of Virginia is proposing a change from volumetric based (Mcf) billing to thermal based (Btu) billing. The VSCC issued a procedural order in the case on May 28, 2014 which scheduled the case for hearing on December 9, 2014. New rates are subject to refund and are scheduled to become effective October 1, 2014.

Cost Recovery and Trackers. 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 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, gas energy efficiency programs, and bad debt recovery mechanisms.

Comparability of Gas Distribution Operations line item operating results is impacted by regulatory trackers that allow for the recovery in rates of certain costs such as bad debt expenses. Increases in the expenses that are subject to trackers result in a corresponding increase in net revenues and therefore have essentially no impact on total operating income results.

Certain of the NiSource distribution companies have completed rate proceedings involving infrastructure replacement or are embarking upon regulatory initiatives to replace significant portions of their operating systems that are nearing the end of their useful lives. Each LDC's approach to cost recovery may be unique, given the different laws, regulations and precedent that exist in each jurisdiction.

Columbia Pipeline Group Operations Regulatory Matters

Significant Rate Developments. On January 30, 2014, Columbia Transmission received FERC approval of its December 2013 filing to recover costs associated with the first year of its comprehensive system modernization program. During 2013, Columbia Transmission completed more than 30 individual projects representing a total investment of about $300 million. The program includes replacement of aging pipeline and compressor facilities, enhancements to system inspection capabilities, and improvements in real-time analytics and control systems. Recovery of the 2013 investments began on February 1, 2014.

The second year of the program includes planned modernization investments of approximately $300 million. Columbia Transmission and its customers have agreed to the initial five years of the comprehensive modernization program, with an opportunity to mutually extend the agreement.

Cost Recovery Trackers. A significant portion of the regulated transmission and storage companies' revenue is related to the recovery of their operating costs, the review and recovery of which occurs via standard regulatory proceedings with the FERC under section 4 of the Natural Gas Act. However, certain operating costs of the NiSource regulated transmission and storage companies are significant and recurring in nature, such as fuel for compression and lost and unaccounted for gas. The FERC allows for the recovery of such costs via cost tracking mechanisms. These tracking mechanisms allow the transmission and storage companies' rates to fluctuate in response to changes in certain operating costs or conditions as they occur to facilitate the timely recovery of its costs incurred. The tracking mechanisms involve a rate adjustment that is filed at a predetermined frequency, typically annually, with the FERC and is subject to regulatory review before new rates go into effect. Other such costs under regulatory tracking mechanisms include third-party pipeline transportation, electric compression, certain environmental, and certain operational purchases and sales of natural gas.

Electric Operations Regulatory Matters

Significant Rate Developments. On July 19, 2013, NIPSCO filed its electric TDSIC, further discussed above, with the IURC. The filing included the seven-year plan of eligible investments for a total of approximately $1.1 billion with the majority of the spend occurring in years 2016 through 2020. On February 17, 2014, the IURC issued an order approving NIPSCO’s seven-year plan of eligible investments. The Order also granted NIPSCO ratemaking relief associated with the eligible investments through a rate adjustment mechanism. NIPSCO anticipates filing its first semi-annual tracker petition in the third quarter of 2014. On March 10, 2014, the OUCC filed a Petition for Reconsideration with the IURC, and the IURC denied that Petition for Reconsideration on May 7, 2014. In addition, the NIPSCO Industrial Group and the OUCC have filed Notices of Appeal with the Indiana Court of Appeals in response to the IURC's ruling, which are still pending.

On November 12, 2013, several industrial customers, including INDIEC, filed a complaint at the FERC regarding the 12.38% base ROE used to set the MISO Transmission Owners' transmission rates and requesting a reduction in the base ROE to 9.15%. The complaint further requests that FERC limit the capital structure of MISO Transmission Owners to no more than 50% common equity for ratemaking purposes and that FERC eliminate incentive adders for membership in a RTO. NIPSCO joined in an answer defending the 12.38% base ROE and motion to dismiss the complaint filed on behalf of a group of MISO Transmission Owners on January 6, 2014. NIPSCO is unable to estimate the impact of this complaint or the timing of any potential impact at this time.

Cost Recovery and Trackers. A significant portion of NIPSCO's revenue is related to the recovery of fuel costs to generate power and purchased power. These costs are recovered through a FAC, a standard, quarterly, “summary” regulatory proceeding in Indiana.

Certain operating costs of the Electric Operations are significant, recurring in nature, and generally outside the control of NIPSCO. The IURC allows for recovery of such costs via cost tracking mechanisms. Such tracking mechanisms allow for abbreviated regulatory proceedings in order for NIPSCO to implement charges and recover appropriate costs. Tracking mechanisms allow for more timely recovery of such costs as compared with more traditional cost recovery mechanisms. Examples of such mechanisms include electric energy efficiency programs, MISO non-fuel costs and revenues, federally mandated costs, resource capacity charges, and environmental related costs.

NIPSCO has approval from the IURC to recover certain environmental related costs through an ECT. Under the ECT, NIPSCO is permitted to recover (1) AFUDC and a return on the capital investment expended by NIPSCO to implement environmental compliance plan projects through an ECRM and (2) related operation and maintenance and depreciation expenses once the environmental facilities become operational through an EERM. On April 30, 2014, the IURC issued an order on ECR-23 approving NIPSCO’s request to begin earning a return on $583.5 million of net capital expenditures.