Regulatory Matters (Notes)	3 Months Ended
Regulatory Matters (Notes)	Mar. 31, 2019
Schedule of Regulatory Assets and Liabilities [Text Block]	Regulatory Matters On January 22, 2019, DP&L filed a request with the PUCO for a two-year extension of its DMR through October 2022, in the proposed amount of $199.0 million for each of the two additional years. The request was made pursuant to the PUCO’s October 20, 2017 ESP order, which approved the DMR and had the option for DP&L to file for a two-year extension. The extension request was set at a level expected to reduce debt obligations at both DP&L and DPL and to position DP&L to make capital expenditures to maintain and modernize its electric grid. To that end, DP&L’s DMP investments are contingent upon the PUCO approving the two-year extension of its DMR. Impact of tax reform On January 10, 2018, the PUCO initiated a proceeding to consider the impacts of the TCJA to determine the appropriate course of action to pass benefits resulting from the legislation on to ratepayers. The PUCO also directed Ohio utilities to record deferred liabilities for the estimated reduction in federal income tax resulting from the TCJA beginning January 1, 2018. Beginning October 1, 2018, the new distribution rates approved in the DRO include the impacts of the decrease in current federal income taxes as a result of the TCJA. Under the terms of the stipulation approved in the DRO, DP&L agreed to file an application at the PUCO to refund eligible excess accumulated deferred income taxes ("ADIT") and any related regulatory liability over a 10-year period. DP&L made such a filing on March 1, 2019 and proposed to return a total of $65.1 million to customers. The timing and final amount to be returned to customers is unknown at this time. Excess ADIT related to depreciation life and method differences will be returned to customers in accordance with federal tax law and related regulations.
Subsidiaries [Member]
Schedule of Regulatory Assets and Liabilities [Text Block]	Regulatory Matters On January 22, 2019, DP&L filed a request with the PUCO for a two-year extension of its DMR through October 2022, in the proposed amount of $199.0 million for each of the two additional years. The request was made pursuant to the PUCO’s October 20, 2017 ESP order, which approved the DMR and had the option for DP&L to file for a two-year extension. The extension request was set at a level expected to reduce debt obligations at both DP&L and DPL and to position DP&L to make capital expenditures to maintain and modernize its electric grid. To that end, DP&L’s DMP investments are contingent upon the PUCO approving the two-year extension of its DMR. Impact of tax reform On January 10, 2018, the PUCO initiated a proceeding to consider the impacts of the TCJA to determine the appropriate course of action to pass benefits resulting from the legislation on to ratepayers. The PUCO also directed Ohio utilities to record deferred liabilities for the estimated reduction in federal income tax resulting from the TCJA beginning January 1, 2018. Beginning October 1, 2018, the new distribution rates approved in the DRO include the impacts of the decrease in current federal income taxes as a result of the TCJA. Under the terms of the stipulation approved in the DRO, DP&L agreed to file an application at the PUCO to refund eligible excess accumulated deferred income taxes ("ADIT") and any related regulatory liability over a 10-year period. DP&L made such a filing on March 1, 2019 and proposed to return a total of $65.1 million to customers. The timing and final amount to be returned to customers is unknown at this time. Excess ADIT related to depreciation life and method differences will be returned to customers in accordance with federal tax law and related regulations.