DPL (DPL) 10-Q 10 Aug 15 2015 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Aug. 07, 2015
Entity Registrant Name	DPL INC
Entity Central Index Key	787,250
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		1
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Entity Voluntary Filers	Yes
Entity Well-known Seasoned Issuer	No
THE DAYTON POWER AND LIGHT COMPANY [Member]
Entity Registrant Name	DAYTON POWER & LIGHT CO
Entity Central Index Key	27,430
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		41,172,173
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q2
Entity Voluntary Filers	Yes
Entity Well-known Seasoned Issuer	No

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues	$ 372.9	$ 390.1	$ 867.4	$ 850.4
Cost of revenues:
Fuel	54.4	60.8	130.8	150.8
Purchased power	120.6	138.4	314.8	312.5
Amortization of intangibles	0	0.3	0	0.6
Total cost of revenues	175	199.5	445.6	463.9
Gross margin	197.9	190.6	421.8	386.5
Operating expenses:
Operation and maintenance	88.4	96	180.1	200.7
Depreciation and amortization	34.3	33.9	69.3	69.2
General taxes	22.9	21.5	47	49.1
Goodwill impairment	0	0	0	135.8
Fixed-asset impairment	0	0	0	11.5
Other	(0.8)	(0.3)	(0.3)	1.4
Total operating expenses	144.8	151.1	296.1	467.7
Operating income / (loss)	53.1	39.5	125.7	(81.2)
Other income / (expense), net
Investment income / (loss)	0.2	0	0	0.4
Interest expense	(30.9)	(31.9)	(61.4)	(62.7)
Other expense	(0.2)	(1.9)	(0.7)	(1)
Total other expense, net	(30.9)	(33.8)	(62.1)	(63.3)
Earnings / (loss) before income taxes	22.2	5.7	63.6	(144.5)
Income tax expense / (benefit)	0.5	(28.1)	13.2	70.7
Net income / (loss)	21.7	33.8	50.4	(215.2)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Revenues	352.1	365.5	813.4	797.6
Cost of revenues:
Fuel	50.6	58.6	119.9	142.9
Purchased power	120.1	136.9	309.8	304.9
Total cost of revenues	170.7	195.5	429.7	447.8
Gross margin	181.4	170	383.7	349.8
Operating expenses:
Operation and maintenance	83.2	84.6	167.1	180
Depreciation and amortization	34.2	35.3	68.9	71.8
General taxes	21.9	20.5	44.9	46.9
Other	0	1.1	0.4	1.4
Total operating expenses	139.3	141.5	281.3	300.1
Operating income / (loss)	42.1	28.5	102.4	49.7
Other income / (expense), net
Investment income / (loss)	0.3	0.1	0.2	0.4
Interest expense	(9)	(8.3)	(17.7)	(16.1)
Other expense	(0.1)	(0.4)	(0.3)	(0.7)
Total other expense, net	(8.8)	(8.6)	(17.8)	(16.4)
Earnings / (loss) before income taxes	33.3	19.9	84.6	33.3
Income tax expense / (benefit)	9.4	6	24.2	10
Net income / (loss)	23.9	13.9	60.4	23.3
Dividends on preferred stock	0.2	0.2	0.4	0.4
Income attributable to common stock	$ 23.7	$ 13.7	$ 60	$ 22.9

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income/(Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net income/ (loss)	$ 21.7	$ 33.8	$ 50.4	$ (215.2)
Available-for-sale securities activity:
Change in fair value of available-for-sale securities, net of income tax	(0.4)	0.1	0.1	(0.2)
Reclassification to earnings, net of income tax	0.4	0	0	0.2
Total change in fair value of available-for-sale securities	0	0.1	0.1	0
Derivative activity:
Change in derivative fair value, net of income tax	1.7	(12.1)	1.8	(25)
Reclassification of earnings, net of income tax	(1.9)	5.3	(1.4)	10.8
Total change in fair value of derivatives	(0.2)	(6.8)	0.4	(14.2)
Pension and postretirement activity:
Reclassification to earnings, net of income tax	(0.4)	0	(0.2)	0
Total change in unfunded pension obligation	(0.4)	0	(0.2)	0
Other comprehensive income / (loss)	(0.6)	(6.7)	0.3	(14.2)
Net comprehensive income / (loss)	21.1	27.1	50.7	(229.4)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Net income/ (loss)	23.9	13.9	60.4	23.3
Available-for-sale securities activity:
Change in fair value of available-for-sale securities, net of income tax	(0.5)	0.1	0	(0.2)
Reclassification to earnings, net of income tax	0.4	0	0	0.2
Total change in fair value of available-for-sale securities	(0.1)	0.1	0	0
Derivative activity:
Change in derivative fair value, net of income tax	1.7	(14.8)	1.8	(27.7)
Reclassification of earnings, net of income tax	(1.8)	6.4	(1.3)	12.1
Total change in fair value of derivatives	(0.1)	(8.4)	0.5	(15.6)
Pension and postretirement activity:
Reclassification to earnings, net of income tax	0.9	0.8	1.8	1.4
Total change in unfunded pension obligation	0.9	0.8	1.8	1.4
Other comprehensive income / (loss)	0.7	(7.5)	2.3	(14.2)
Net comprehensive income / (loss)	$ 24.6	$ 6.4	$ 62.7	$ 9.1

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income/(Loss) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income tax (expense)/benefit on unrealized gains (losses) related to available-for-sale securities	$ 0.3	$ (0.1)	$ 0	$ 0.1
Income tax (expense) benefit on reclassification to earnings	(0.2)	0	0	(0.1)
Income tax (expense)/benefit on unrealized gains (losses) related to derivative activity	(1)	6.3	(1)	13.3
Income tax (expense)/benefit on reclassification of earnings related to derivative activity	0.9	(2.7)	0.5	(5.8)
Income tax (expense)/benefit on reclassification of earnings related to pension and postretirement activity	(0.5)	0	(0.4)	0
THE DAYTON POWER AND LIGHT COMPANY [Member]
Income tax (expense)/benefit on unrealized gains (losses) related to available-for-sale securities	0.2	(0.1)	0	0.1
Income tax (expense) benefit on reclassification to earnings	(0.2)	0	0	(0.1)
Income tax (expense)/benefit on unrealized gains (losses) related to derivative activity	(1)	3.7	(1)	10.6
Income tax (expense)/benefit on reclassification of earnings related to derivative activity	1	(1.6)	0.7	(4.8)
Income tax (expense)/benefit on reclassification of earnings related to pension and postretirement activity	$ (0.5)	$ (0.3)	$ (1)	$ (0.7)

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 116.6	$ 17
Restricted cash	25.2	16.8
Accounts receivable, net	175.7	200.9
Inventories	104.7	100.2
Taxes applicable to subsequent years	39.1	77.8
Regulatory assets, current	30.1	44.2
Other prepayments and current assets	42.7	41.8
Total current assets	534.1	498.7
Property, plant & equipment:
Property, plant & equipment	2,860.6	2,759.3
Less: Accumulated depreciation and amortization	(377.2)	(318.4)
Property, plant and equipment, net of depreciation	2,483.4	2,440.9
Construction work in process	64.4	76.7
Total net property, plant & equipment	2,547.8	2,517.6
Other non-current assets:
Regulatory assets, non-current	155	167.5
Goodwill	317	317
Intangible assets, net of amortization	30.9	37.4
Other deferred assets	39.7	39.6
Total other non-current assets	542.6	561.5
Total assets	3,624.5	3,577.8
Current liabilities:
Current portion of long-term debt	149.5	20.1
Accounts payable	101.6	109.2
Accrued taxes	133.5	102.6
Accrued interest	27.3	27.2
Customer security deposits	13.8	14.4
Regulatory liabilities, current	14.4	4.4
Insurance and claims costs	5.6	6.4
Other current liabilities	50.6	48.7
Total current liabilities	496.3	333
Non-current liabilities:
Long-term debt	2,010.3	2,139.6
Deferred taxes	554	587.3
Taxes payable	34.5	80.9
Regulatory liabilities, non-current	125.1	124.1
Pension, retiree and other benefits	95.9	95.9
Unamortized investment tax credit	2	2.2
Other deferred credits	88.9	48.2
Total non-current liabilities	2,910.7	3,078.2
Redeemable preferred stock of subsidiary	$ 18.4	$ 18.4
Commitments and contingencies
Common shareholder's equity:
Common stock	$ 0	$ 0
Other paid-in capital	2,237.6	2,237.4
Accumulated other comprehensive income	7.8	7.5
Retained earnings/ (deficit)	(2,046.3)	(2,096.7)
Total common shareholder's equity	199.1	148.2
Total liabilities and shareholder's equity	3,624.5	3,577.8
THE DAYTON POWER AND LIGHT COMPANY [Member]
Current assets:
Cash and cash equivalents	85.1	5.4
Restricted cash	25.1	16.7
Accounts receivable, net	137.6	152.7
Inventories	103.5	99
Taxes applicable to subsequent years	38.1	75.4
Regulatory assets, current	30.1	44.2
Other prepayments and current assets	39.6	41.1
Total current assets	459.1	434.5
Property, plant & equipment:
Property, plant & equipment	5,196.8	5,120.7
Less: Accumulated depreciation and amortization	(2,531.4)	(2,495.7)
Property, plant and equipment, net of depreciation	2,665.4	2,625
Construction work in process	63.1	75.4
Total net property, plant & equipment	2,728.5	2,700.4
Other non-current assets:
Regulatory assets, non-current	155	167.5
Intangible assets, net of amortization	4.5	7.8
Other deferred assets	30.6	28.5
Total other non-current assets	190.1	203.8
Total assets	3,377.7	3,338.7
Current liabilities:
Current portion of long-term debt	114.5	0.1
Accounts payable	99.7	104.8
Accrued taxes	119.8	82.6
Accrued interest	9.9	9.8
Customer security deposits	16.2	34.5
Regulatory liabilities, current	14.4	4.4
Other current liabilities	48.5	44.8
Total current liabilities	423	281
Non-current liabilities:
Long-term debt	762.7	877
Deferred taxes	623.2	650
Taxes payable	33.1	78.4
Regulatory liabilities, non-current	125.1	124.1
Pension, retiree and other benefits	95.9	95.9
Unamortized investment tax credit	21.2	22.4
Other deferred credits	84.8	43.6
Total non-current liabilities	1,746	1,891.4
Redeemable preferred stock of subsidiary	$ 22.9	$ 22.9
Commitments and contingencies
Common shareholder's equity:
Common stock	$ 0.4	$ 0.4
Other paid-in capital	803.6	803.5
Accumulated other comprehensive income	(40)	(42.3)
Retained earnings/ (deficit)	421.8	381.8
Total common shareholder's equity	1,185.8	1,143.4
Total liabilities and shareholder's equity	$ 3,377.7	$ 3,338.7

Condensed Consolidated Balance6

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2015	Dec. 31, 2014
Common stock, shares authorized	1,500	1,500
Common stock, shares issued	1	1
Common stock, shares outstanding	1	1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Common stock, shares authorized	250,000,000
Common stock, shares outstanding	41,172,173
Common stock, par value (in USD per share)	$ 0.01	$ 0.01

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income/ (loss)	$ 50.4	$ (215.2)
Adjustments to reconcile net income / (loss) to net cash from operating activities:
Depreciation and amortization	69.3	69.2
Amortization of intangibles	0	0.6
Deferred income taxes	(17.5)	(2.3)
Goodwill impairment	0	135.8
Fixed-asset impairment	0	11.5
Changes in certain assets and liabilities:
Accounts receivable	25	6.6
Inventories	(4.5)	(12.7)
Prepaid taxes	(0.5)	1
Taxes applicable to subsequent years	38.6	33.5
Deferred regulatory costs, net	21.3	(4.3)
Accounts payable	3.3	18.3
Accrued taxes payable	(15.5)	35.8
Accrued interest payable	0	(0.4)
Pension, retiree and other benefits	3.8	(6.2)
Other	(2.2)	(18.5)
Net cash provided by operating activities	171.5	52.7
Cash flows from investing activities:
Capital expenditures	(64.8)	(55.2)
Proceeds from sale of business	1.3	0
Increase in restricted cash	(8.4)	(11)
Other investing activities, net	0.4	1.2
Net cash used by investing activities	(71.7)	(66.5)
Cash flows from financing activities:
Payments of deferred financing costs	(0.1)	(0.1)
Borrowings from revolving credit facilities	15	115
Repayment of borrowings from revolving credit facilities	(15)	(115)
Retirement of long-term debt	(0.1)	(0.1)
Net cash used by financing activities	(0.2)	(0.2)
Cash and cash equivalents:
Net change	99.6	(14)
Balance at beginning of period	17	53.2
Cash and cash equivalents at end of period	116.6	39.2
Supplemental cash flow information:
Interest paid, net of amounts capitalized	55.6	59.3
Income taxes paid / (refunded), net	0.5	0.2
Non-cash financing and investing activities:
Accruals for capital expenditures	10	7.9
THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from operating activities:
Net income/ (loss)	60.4	23.3
Adjustments to reconcile net income / (loss) to net cash from operating activities:
Depreciation and amortization	68.9	71.8
Deferred income taxes	(11.6)	2.7
Changes in certain assets and liabilities:
Accounts receivable	16.2	(0.3)
Inventories	(4.7)	(12.6)
Prepaid taxes	(0.2)	0
Taxes applicable to subsequent years	37.4	32.3
Deferred regulatory costs, net	21.3	(4.3)
Accounts payable	3.3	18.4
Accrued taxes payable	(8)	(31.6)
Accrued interest payable	0	0.1
Pension, retiree and other benefits	3.8	(6.2)
Other	(18.9)	(18.3)
Net cash provided by operating activities	167.9	75.3
Cash flows from investing activities:
Capital expenditures	(63.3)	(53)
Insurance proceeds	3.8	0.4
Increase in restricted cash	(8.4)	(11.4)
Other investing activities, net	0.4	1.3
Net cash used by investing activities	(67.7)	(64.2)
Cash flows from financing activities:
Payments of deferred financing costs	0	(0.2)
Dividends paid on common stock to parent	(20)	(15)
Borrowings from revolving credit facilities	15	0
Issuance of notes payable - related party	0	15
Repayment of notes payable - related party	0	(15)
Dividends paid on preferred stock	(0.4)	(0.4)
Repayment of borrowings from revolving credit facilities	(15)	0
Retirement of long-term debt	(0.1)	(0.1)
Net cash used by financing activities	(20.5)	(15.7)
Cash and cash equivalents:
Net change	79.7	(4.6)
Balance at beginning of period	5.4	22.9
Cash and cash equivalents at end of period	85.1	18.3
Supplemental cash flow information:
Interest paid, net of amounts capitalized	13.5	13.6
Income taxes paid / (refunded), net	0.5	0.2
Non-cash financing and investing activities:
Accruals for capital expenditures	10	7.9
Emission Allowances [Member]
Cash flows from investing activities:
Purchase of intangible assets	0	(0.1)
Emission Allowances [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from investing activities:
Purchase of intangible assets	0	(0.1)
Renewable Energy Credits [Member]
Cash flows from investing activities:
Purchase of intangible assets	(0.2)	(1.4)
Renewable Energy Credits [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Cash flows from investing activities:
Purchase of intangible assets	$ (0.2)	$ (1.4)

Overview and Summary of Signifi

Overview and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2015
Significant Accounting Policies [Line Items]
Overview and Summary of Significant Accounting Policies	Overview and Summary of Significant Accounting Policies Description of Business DPL is a diversified regional energy company organized in 1985 under the laws of Ohio. DPL’s two reportable segments are the Utility segment, comprised of its DP&L subsidiary, and the Competitive Retail segment, comprised of its DPLER operations, which included the operations of DPLER’s wholly owned subsidiary MC Squared. MC Squared was sold effective April 1, 2015. See Note 11 for more information relating to these reportable segments. The terms “we,” “us,” “our” and “ours” are used to refer to DPL and its subsidiaries. DPL is an indirectly wholly owned subsidiary of AES. DP&L is a public utility incorporated in 1911 under the laws of Ohio. Beginning in 2001, Ohio law gave Ohio consumers the right to choose the electric generation supplier from whom they purchase retail generation service, however distribution and transmission retail services are still regulated. DP&L has the exclusive right to provide such distribution and transmission services to its more than 516,000 customers located in West Central Ohio. Additionally, DP&L offers retail SSO electric service to residential, commercial, industrial and governmental customers in a 6,000 square mile area of West Central Ohio and generates electricity at five coal-fired power stations. During 2015, DP&L is required to source 60% of the generation for its SSO customers through a competitive bid process and beginning January 2016, generation for its SSO customers will be 100% competitively bid. Principal industries located in DP&L’s service territory include automotive, food processing, paper, plastic, manufacturing and defense. DP&L's sales reflect the general economic conditions, seasonal weather patterns, retail competition in our service territory and the market price of electricity. DP&L sells any excess energy and capacity into the wholesale market. On June 4, 2014, the PUCO issued an entry on rehearing which requires DP&L to separate its generation assets from its transmission and distribution assets no later than January 1, 2017. While the OCC filed an application for rehearing on this Commission Order, it was denied by final order issued on July 23, 2014. DP&L also sells electricity to DPLER, an affiliate, to satisfy the electric requirements of DPLER’s retail customers. DPLER sells competitive retail electric service, under contract, to residential, commercial, industrial and governmental customers in Ohio. As of June 30, 2015 , DPLER has approximately 133,000 customers currently located throughout Ohio. On April 1, 2015, DPLER closed on the sale of its former subsidiary, MC Squared. DPLER does not own any transmission or generation assets, and all of DPLER’s electric energy was purchased from DP&L to meet its sales obligations. DPLER’s sales reflect the general economic conditions and seasonal weather patterns of the areas it serves. DPL’s other significant subsidiaries include DPLE, which owns and operates peaking generating facilities from which it makes wholesale sales of electricity, and MVIC, our captive insurance company that provides insurance services to our subsidiaries and us. DPL owns all of the common stock of its subsidiaries. DPL also has a wholly owned business trust, DPL Capital Trust II, formed for the purpose of issuing trust capital securities to investors. DP&L’s electric transmission and distribution businesses are subject to rate regulation by federal and state regulators while its generation business is deemed competitive under Ohio law. Accordingly, DP&L applies the accounting standards for regulated operations to its electric transmission and distribution businesses and records regulatory assets when incurred costs are expected to be recovered in future customer rates, and regulatory liabilities when current cost recoveries in customer rates relate to expected future costs. DPL and its subsidiaries employed 1,189 people as of June 30, 2015 , of which 1,151 were employed by DP&L . Approximately 61% of all DPL employees are under a collective bargaining agreement that expires on October 31, 2017. Financial Statement Presentation DPL’s Condensed Consolidated Financial Statements include the accounts of DPL and its wholly owned subsidiaries except for DPL Capital Trust II, which is not consolidated, consistent with the provisions of GAAP. DP&L has undivided ownership interests in five coal-fired generating facilities, various peaking generating facilities and numerous transmission facilities, all of which are included in the financial statements at amortized cost, which was adjusted to fair value at the date of the Merger for DPL . Operating revenues and expenses of these facilities are included on a pro rata basis in the corresponding lines in the Condensed Consolidated Statements of Operations. See Note 4 for more information. Certain immaterial amounts from prior periods have been reclassified to conform to the current period presentation. All material intercompany accounts and transactions are eliminated in consolidation. These financial statements have been prepared in accordance with GAAP for interim financial statements, the instructions of Form 10-Q and Regulation S-X. Accordingly, certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with GAAP have been omitted from this interim report. Therefore, our interim financial statements in this report should be read along with the annual financial statements included in our Form 10-K for the fiscal year ended December 31, 2014 . In the opinion of our management, the Condensed Consolidated Financial Statements presented in this report contain all adjustments necessary to fairly state our financial position as of June 30, 2015 ; our results of operations for the three and six months ended June 30, 2015 and 2014 and our cash flows for the six months ended June 30, 2015 and 2014 . Unless otherwise noted, all adjustments are normal and recurring in nature. Due to various factors, including, but not limited to, seasonal weather variations, the timing of outages of EGUs, changes in economic conditions involving commodity prices and competition, and other factors, interim results for the three and six months ended June 30, 2015 may not be indicative of our results that will be realized for the full year ending December 31, 2015 . The preparation of financial statements in conformity with GAAP requires us to make estimates and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the revenues and expenses of the periods reported. Actual results could differ from these estimates. Significant items subject to such estimates and judgments include: the carrying value of property, plant and equipment; unbilled revenues; the valuation of derivative instruments; the valuation of insurance and claims liabilities; the valuation of allowances for receivables and deferred income taxes; regulatory assets and liabilities; liabilities recorded for income tax exposures; litigation; contingencies; the valuation of AROs; assets and liabilities related to employee benefits; goodwill; and intangibles. As a result of push down accounting, DPL’s Condensed Consolidated Statements of Operations subsequent to the Merger include amortization expense relating to purchase accounting adjustments and depreciation of fixed assets based upon their fair value at the Merger date. Sale of Receivables DPLER and its former subsidiary MC Squared sell their customer receivables. These sales are at a small discount for cash at the billed amounts for their customers’ use of energy. Total receivables sold during the three months ended June 30, 2015 and 2014 were $6.6 million and $28.9 million , respectively. Total receivables sold during the six months ended June 30, 2015 and 2014 were $39.7 million and $61.0 million , respectively. Accounting for Taxes Collected from Customers and Remitted to Governmental Authorities DPL collects certain excise taxes levied by state or local governments from its customers. These taxes are accounted for on a net basis and not included in revenue. The amounts of such taxes collected for the three months ended June 30, 2015 and 2014 were $11.5 million and $11.6 million , respectively. The amounts of such taxes collected for the six months ended June 30, 2015 and 2014 were $25.5 million and $25.9 million , respectively. Related Party Transactions In December 2013, an agreement was signed, effective January 1, 2014, whereby the Service Company is to provide services including accounting, legal, human resources, information technology and other corporate services on behalf of companies that are part of the U.S. SBU, including, among other companies, DPL and DP&L . The Service Company allocates the costs for these services based on cost drivers designed to result in fair and equitable allocations. This includes ensuring that the regulated utilities served, including DP&L , are not subsidizing costs incurred for the benefit of non-regulated businesses. DPL charges the Service Company for employee payroll and benefit costs that are incurred on behalf of the Service Company. In the normal course of business, DPL enters into transactions with subsidiaries of AES. The following table provides a summary of these transactions: Three months ended Six months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Transactions with the Service Company Charges from the Service Company $ 9.8 $ 6.3 $ 19.6 $ 16.7 Charges to the Service Company $ 2.8 $ 0.6 $ 3.9 $ 1.1 at June 30, 2015 at December 31, 2014 Net prepaid / (payable) to the service company $ 4.0 $ (4.7 ) DPL has issued debt to a wholly owned business trust, DPL Capital Trust II. See Note 5 for further information. Recently Issued Accounting Standards ASU No. 2015-03, Interest – Imputation of Interest (Subtopic 835-30) In April 2015, the FASB issued ASU No. 2015-03, which simplifies the presentation of debt issuance costs by requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this update. The standard is effective for annual reporting periods beginning after December 15, 2015 and interim periods therein, and requires the use of the full retrospective approach. Early adoption is permitted for financial statements that have not been previously issued. As of June 30, 2015 , DPL had approximately $19.0 million in deferred financing costs classified in other non-current assets that would be reclassified to reduce the related debt liabilities upon adoption of ASU No. 2015-03. ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) In May 2014, the FASB issued ASU No. 2014-09 which clarifies principles for recognizing revenue and will result in a common revenue standard for GAAP and International Financial Reporting Standards. The objective of the new standard is to provide a single and comprehensive revenue recognition model for all contracts with customers to improve comparability, and it supersedes prior, industry-specific guidance. The revenue standard contains principles that an entity will apply to determine the measurement of revenue and timing of when revenue is recognized. The standard requires an entity to recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. In July 2015, the FASB decided to defer the effective date by one year, resulting in the new revenue standard being effective for annual reporting periods beginning after December 15, 2017 and interim periods therein. Early adoption is now permitted only as of the original effective date for public entities (that is, no earlier than 2017 for calendar year-end entities). The standard permits the use of two transition methods: either a full retrospective or modified retrospective approach. We have not yet selected a transition method and we are currently evaluating the impact of adopting the standard on our consolidated financial statements effective January 1, 2018. ASU No. 2015-11, Inventory: Simplifying the Measurement of Inventory (Topic 330) In July 2015, the FASB issued ASU No. 2015-11, which simplifies the subsequent measurement of inventory. It replaces the current lower of cost or market test with a lower of cost or net realizable value test. The standard is effective for public entities for annual reporting periods beginning after December 15, 2016, and interim periods therein. Early adoption is permitted. The new guidance must be applied prospectively. We are currently evaluating the impact of adopting the standard on our consolidated financial statements.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Significant Accounting Policies [Line Items]
Overview and Summary of Significant Accounting Policies	Overview and Summary of Significant Accounting Policies Description of Business DP&L is a public utility incorporated in 1911 under the laws of Ohio. Beginning in 2001, Ohio law gave Ohio consumers the right to choose the electric generation supplier from whom they purchase retail generation service, however distribution and transmission retail services are still regulated. DP&L has the exclusive right to provide such distribution and transmission services to its more than 516,000 customers located in West Central Ohio. Additionally, DP&L offers retail SSO electric service to residential, commercial, industrial and governmental customers in a 6,000 square mile area of West Central Ohio. DP&L owns multiple coal-fired and peaking electric generating facilities as well as numerous transmission facilities, all of which are included in the financial statements at amortized cost. During 2015, DP&L is required to source 60% of the generation for its SSO customers through a competitive bid process, followed by 100% beginning in 2016. Principal industries located in DP&L’s service territory include automotive, food processing, paper, plastic, manufacturing and defense. DP&L's sales reflect the general economic conditions, seasonal weather patterns, retail competition in our service territory and the market price of electricity. DP&L sells any excess energy and capacity into the wholesale market. On June 4, 2014, the PUCO issued an entry on rehearing which requires DP&L to separate its generation assets from its transmission and distribution assets no later than January 1, 2017. While the OCC filed an application for rehearing on this Commission Order, it was denied by final order issued on July 23, 2014. DP&L also sells electricity to DPLER, an affiliate, to satisfy the electric requirements of DPLER’s retail customers. DP&L is a subsidiary of DPL . DP&L’s electric transmission and distribution businesses are subject to rate regulation by federal and state regulators while its generation business is deemed competitive under Ohio law. Accordingly, DP&L applies the accounting standards for regulated operations to its electric transmission and distribution businesses and records regulatory assets when incurred costs are expected to be recovered in future customer rates, and regulatory liabilities when current cost recoveries in customer rates relate to expected future costs. DP&L employed 1,151 people as of June 30, 2015 . Approximately 63% of all employees are under a collective bargaining agreement which expires on October 31, 2017. Financial Statement Presentation DP&L does not have any subsidiaries. DP&L has undivided ownership interests in five coal-fired generating facilities, peaking electric generating facilities and numerous transmission facilities, all of which are included in the financial statements at amortized cost. Operating revenues and expenses of these facilities are included on a pro rata basis in the corresponding lines in the Condensed Statements of Operations. See Note 4 for more information. Certain immaterial amounts from prior periods have been reclassified to conform to the current period presentation. These financial statements have been prepared in accordance with GAAP for interim financial statements, the instructions of Form 10-Q and Regulation S-X. Accordingly, certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with GAAP have been omitted from this interim report. Therefore, our interim financial statements in this report should be read along with the annual financial statements included in our Form 10-K for the fiscal year ended December 31, 2014 . In the opinion of our management, the Condensed Financial Statements presented in this report contain all adjustments necessary to fairly state our financial position as of June 30, 2015 ; our results of operations for the three and six months ended June 30, 2015 and 2014 and our cash flows for the six months ended June 30, 2015 and 2014. Unless otherwise noted, all adjustments are normal and recurring in nature. Due to various factors, including, but not limited to, seasonal weather variations, the timing of outages of EGUs, changes in economic conditions involving commodity prices and competition, and other factors, interim results for the six months ended June 30, 2015 may not be indicative of our results that will be realized for the full year ending December 31, 2015 . The preparation of financial statements in conformity with GAAP requires us to make estimates and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the revenues and expenses of the periods reported. Actual results could differ from these estimates. Significant items subject to such estimates and judgments include: the carrying value of property, plant and equipment; unbilled revenues; the valuation of derivative instruments; the valuation of insurance and claims liabilities; the valuation of allowances for receivables and deferred income taxes; regulatory assets and liabilities; liabilities recorded for income tax exposures; litigation; contingencies; the valuation of AROs; intangibles and assets and liabilities related to employee benefits. Accounting for Taxes Collected from Customers and Remitted to Governmental Authorities DP&L collects certain excise taxes levied by state or local governments from its customers. These taxes are accounted for on a net basis and not included in revenue. The amounts of such taxes collected for the three months ended June 30, 2015 and 2014 were $11.5 million and $11.6 million , respectively. The amounts of such taxes collected for the six months ended June 30, 2015 and 2014 were $25.5 million and $25.9 million , respectively. Related Party Transactions In December 2013, an agreement was signed, effective January 1, 2014, whereby the Service Company is to provide services including accounting, legal, human resources, information technology and other corporate services on behalf of companies that are part of the U.S. SBU, including, among other companies, DP&L . The Service Company allocates the costs for these services based on cost drivers designed to result in fair and equitable allocations. This includes ensuring that the regulated utilities served, including DP&L , are not subsidizing costs incurred for the benefit of non-regulated businesses. DP&L charges the Service Company for employee payroll and benefit costs that are incurred on behalf of the Service Company. In the normal course of business, DP&L enters into transactions with other subsidiaries of DPL and AES . The following table provides a summary of these transactions: Three months ended Six months ended $ in millions 2015 2014 2015 2014 DP&L Revenues: Sales to DPLER (including MC Squared) (a) $ 68.3 $ 111.5 $ 179.0 $ 251.0 DP&L Operations and Maintenance Expenses: Premiums paid for insurance services provided by MVIC (b) $ (0.8 ) $ (0.7 ) $ (1.6 ) $ (1.4 ) Expense recoveries for services provided to DPLER (c) $ 0.6 $ 1.1 $ 1.3 $ 1.1 Transactions with the Service Company Charges from the Service Company $ 8.3 $ 6.4 $ 16.7 $ 16.8 Charges to the Service Company $ 2.8 $ 0.6 $ 3.9 $ 1.1 DP&L Customer security deposits: at June 30, 2015 at December 31, 2014 Deposits received from DPLER (d) $ 2.4 $ 20.1 Balances with the Service Company Net prepaid / (payable) to the service company $ 4.0 $ (4.7 ) (a) DP&L sells power to DPLER to satisfy the electric requirements of DPLER’s retail customers. The revenue dollars associated with sales to DPLER are recorded as wholesale revenues in DP&L’s Financial Statements. (b) MVIC, a wholly owned captive insurance subsidiary of DPL , provides insurance coverage to DP&L and other DPL subsidiaries for workers’ compensation, general liability, property damages and directors’ and officers’ liability. These amounts represent insurance premiums paid by DP&L to MVIC. DP&L received insurance proceeds from MVIC of $2.3 million and $0.4 million for the three months ended June 30, 2015 and 2014, respectively, and $3.8 million and $0.4 million for the six months ended June 30, 2015 and 2014, respectively. (c) In the normal course of business DP&L incurs and records expenses on behalf of DPLER. Such expenses include, but are not limited to, employee-related expenses, accounting, information technology, payroll, legal and other administrative expenses. DP&L subsequently charges these expenses to DPLER at DP&L’s cost and credits the expense in which they were initially recorded. (d) DP&L requires credit assurance from the CRES providers serving customers in its service territory because DP&L is the default energy provider should the CRES provider fail to fulfill its obligations to provide electricity. Due to DPL’s credit downgrade, DP&L required cash collateral from DPLER. Recently Issued Accounting Standards ASU No. 2015-03, Interest – Imputation of Interest (Subtopic 835-30) In April 2015, the FASB issued ASU No. 2015-03, which simplifies the presentation of debt issuance costs by requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this update. The standard is effective for annual reporting periods beginning after December 15, 2015 and interim periods therein, and requires the use of the full retrospective approach. Early adoption is permitted for financial statements that have not been previously issued. As of June 30, 2015 , DP&L had approximately $9.6 million in deferred financing costs classified in other non-current assets that would be reclassified to reduce the related debt liabilities upon adoption of ASU No. 2015-03. ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) In May 2014, the FASB issued ASU No. 2014-09 which clarifies principles for recognizing revenue and will result in a common revenue standard for GAAP and International Financial Reporting Standards. The objective of the new standard is to provide a single and comprehensive revenue recognition model for all contracts with customers to improve comparability, and it supersedes prior, industry-specific guidance. The revenue standard contains principles that an entity will apply to determine the measurement of revenue and timing of when revenue is recognized. The standard requires an entity to recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. In July 2015, the FASB decided to defer the effective date by one year, resulting in the new revenue standard being effective for annual reporting periods beginning after December 15, 2017 and interim periods therein. Early adoption is now permitted only as of the original effective date for public entities (that is, no earlier than 2017 for calendar year-end entities). The standard permits the use of two transition methods: either a full retrospective or modified retrospective approach. We have not yet selected a transition method and we are currently evaluating the impact of adopting the standard on our consolidated financial statements effective January 1, 2018. ASU No. 2015-11, Inventory: Simplifying the Measurement of Inventory (Topic 330) In July 2015, the FASB issued ASU No. 2015-11, which simplifies the subsequent measurement of inventory. It replaces the current lower of cost or market test with a lower of cost or net realizable value test. The standard is effective for public entities for annual reporting periods beginning after December 15, 2016, and interim periods therein. Early adoption is permitted. The new guidance must be applied prospectively. We are currently evaluating the impact of adopting the standard on our financial statements.

Supplemental Financial Informat

Supplemental Financial Information	6 Months Ended
	Jun. 30, 2015
Supplemental Financial Information [Line Items]
Supplemental Financial Information	Supplemental Financial Information Accounts receivable and Inventories are as follows at June 30, 2015 and December 31, 2014 : June 30, December 31, $ in millions 2015 2014 Accounts receivable, net: Unbilled revenue $ 61.9 $ 79.2 Customer receivables 92.0 104.8 Amounts due from partners in jointly owned plants 20.0 14.2 Other 3.2 4.0 Provision for uncollectible accounts (1.4 ) (1.3 ) Total accounts receivable, net $ 175.7 $ 200.9 Inventories, at average cost: Fuel and limestone $ 67.8 $ 65.3 Plant materials and supplies 34.8 33.5 Other 2.1 1.4 Total inventories, at average cost $ 104.7 $ 100.2 Accumulated Other Comprehensive Income / (Loss) The amounts reclassified out of Accumulated Other Comprehensive Income / (Loss) by component during the six months ended June 30, 2015 and 2014 are as follows: Details about Accumulated Other Comprehensive Income / (Loss) components Affected line item in the Condensed Consolidated Statements of Operations Three months ended Six months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Gains and losses on Available-for-sale securities activity (Note 8): Other income $ 0.6 $ — $ — $ 0.3 Tax expense (0.2 ) — — (0.1 ) Net of income taxes 0.4 — — 0.2 Gains and losses on cash flow hedges (Note 9): Interest expense (0.3 ) (0.2 ) (0.5 ) (0.7 ) Revenue (2.9 ) 8.3 (3.2 ) 18.5 Purchased power 0.4 (0.1 ) 1.8 (1.2 ) Total before income taxes (2.8 ) 8.0 (1.9 ) 16.6 Tax expense 0.9 (2.7 ) 0.5 (5.8 ) Net of income taxes (1.9 ) 5.3 (1.4 ) 10.8 Amortization of defined benefit pension items (Note 7): Other income 0.1 — 0.2 — Tax expense (0.5 ) — (0.4 ) — Net of income taxes (0.4 ) — (0.2 ) — Total reclassifications for the period, net of income taxes $ (1.9 ) $ 5.3 $ (1.6 ) $ 11.0 The changes in the components of Accumulated Other Comprehensive Income / (Loss) during the six months ended June 30, 2015 are as follows: $ in millions Gains / (losses) on available-for-sale securities Gains / (losses) on cash flow hedges Change in unfunded pension obligation Total Balance January 1, 2015 $ 0.5 $ 18.5 $ (11.5 ) $ 7.5 Other comprehensive income before reclassifications 0.1 1.8 — 1.9 Amounts reclassified from accumulated other comprehensive income / (loss) — (1.4 ) (0.2 ) (1.6 ) Net current period other comprehensive income / (loss) 0.1 0.4 (0.2 ) 0.3 Balance June 30, 2015 $ 0.6 $ 18.9 $ (11.7 ) $ 7.8
THE DAYTON POWER AND LIGHT COMPANY [Member]
Supplemental Financial Information [Line Items]
Supplemental Financial Information	Supplemental Financial Information Accounts receivable and Inventories are as follows at June 30, 2015 and December 31, 2014 : June 30, December 31, $ in millions 2015 2014 Accounts receivable, net: Unbilled revenue $ 43.5 $ 49.0 Customer receivables 69.5 68.7 Amounts due from partners in jointly owned plants 20.0 14.2 Other 5.6 21.7 Provision for uncollectible accounts (1.0 ) (0.9 ) Total accounts receivable, net $ 137.6 $ 152.7 Inventories, at average cost: Fuel and limestone $ 67.8 $ 65.3 Plant materials and supplies 33.7 32.3 Other 2.0 1.4 Total inventories, at average cost $ 103.5 $ 99.0 Accumulated Other Comprehensive Income / (Loss) The amounts reclassified out of Accumulated Other Comprehensive Income / (Loss) by component during the three and six months ended June 30, 2015 and 2014 are as follows: Details about Accumulated Other Comprehensive Income / (Loss) components Affected line item in the Condensed Statements of Operations Three months ended Six months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Gains and losses on Available-for-sale securities activity (Note 8): Other income $ 0.6 $ — $ — $ 0.3 Tax expense (0.2 ) — — (0.1 ) Net of income taxes 0.4 — — 0.2 Gains and losses on cash flow hedges (Note 9): Interest expense (0.3 ) (0.3 ) (0.6 ) (0.6 ) Revenue (2.9 ) 8.3 (3.2 ) 18.5 Purchased power 0.4 — 1.8 (1.0 ) Total before income taxes (2.8 ) 8.0 (2.0 ) 16.9 Tax expense 1.0 (1.6 ) 0.7 (4.8 ) Net of income taxes (1.8 ) 6.4 (1.3 ) 12.1 Amortization of defined benefit pension items (Note 7): Reclassification to Other income / (deductions) 1.4 1.1 2.8 2.1 Tax benefit (0.5 ) (0.3 ) (1.0 ) (0.7 ) Net of income taxes 0.9 0.8 1.8 1.4 Total reclassifications for the period, net of income taxes $ (0.5 ) $ 7.2 $ 0.5 $ 13.7 The changes in the components of Accumulated Other Comprehensive Income / (Loss) during the six months ended June 30, 2015 are as follows: $ in millions Gains / (losses) on available-for-sale securities Gains / (losses) on cash flow hedges Change in unfunded pension obligation Total Balance January 1, 2015 $ 0.7 $ 2.8 $ (45.8 ) $ (42.3 ) Other comprehensive income before reclassifications — 1.8 — 1.8 Amounts reclassified from accumulated other comprehensive income / (loss) — (1.3 ) 1.8 0.5 Net current period other comprehensive income — 0.5 1.8 2.3 Balance June 30, 2015 $ 0.7 $ 3.3 $ (44.0 ) $ (40.0 )

Regulatory Assets and Liabiliti

Regulatory Assets and Liabilities	6 Months Ended
	Jun. 30, 2015
Regulatory Assets [Line Items]
Regulatory Assets and Liabilities	Regulatory assets and liabilities DP&L has certain rate riders that provide for recovering, on a timely basis, costs incurred for specific programs for which costs may fluctuate. These riders generally allow DP&L to estimate future costs and customer kWh consumption and set rider rates designed to recover those estimated costs as they are incurred. Differences between revenues collected and the actual program costs are tracked and reconciled by increasing or reducing future rates accordingly. DP&L’s current regulatory assets and current regulatory liabilities reflect the reconciliation of such differences, with the exception of deferred storm costs. The deferred storm regulatory asset reflects costs incurred to repair major storm damage in previous years, for which DP&L was granted cost recovery during 2015. The changes in DP&L’s current regulatory asset and liability balances from December 31, 2014 to June 30, 2015 primarily represent the recovery of $11.1 million of deferred storm costs, and the reconciliation of other rider costs.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Assets [Line Items]
Regulatory Assets and Liabilities	Regulatory assets and liabilities DP&L has certain rate riders that provide for recovering, on a timely basis, costs incurred for specific programs for which costs may fluctuate. These riders generally allow DP&L to estimate future costs and customer kWh consumption and set rider rates designed to recover those estimated costs as they are incurred. Differences between revenues collected and the actual program costs are tracked and reconciled by increasing or reducing future rates accordingly. DP&L’s current regulatory assets and current regulatory liabilities reflect the reconciliation of such differences, with the exception of deferred storm costs. The deferred storm regulatory asset reflects costs incurred to repair major storm damage in previous years, for which DP&L was granted cost recovery during 2015. The changes in DP&L’s current regulatory asset and liability balances from December 31, 2014 to June 30, 2015 primarily represent the recovery of $11.1 million of deferred storm costs, and the reconciliation of other rider costs.

Ownership of Coal-fired Facilit

Ownership of Coal-fired Facilities	6 Months Ended
	Jun. 30, 2015
Jointly Owned Utility Plant Interests [Line Items]
Ownership of Coal-fired Facilities	Ownership of Coal-fired Facilities DP&L has undivided ownership interests in five coal-fired electric generating facilities, various peaking facilities and numerous transmission facilities with certain other Ohio utilities. Certain expenses, primarily fuel costs for the generating units, are allocated to the owners based on their energy usage. The remaining expenses, investments in fuel inventory, plant materials and operating supplies, and capital additions are allocated to the owners in accordance with their respective ownership interests. At June 30, 2015 , DP&L had $21.0 million of construction work in process at such jointly owned facilities. DP&L’s share of the operating cost of such facilities is included within the corresponding line in the Condensed Consolidated Statements of Operations and DP&L’s share of the investment in the facilities is included within Total net property, plant and equipment in the Condensed Consolidated Balance Sheets. Each joint owner provides their own financing for their share of the operations and capital expenditures of the jointly owned units and stations. DP&L’s undivided ownership interest in such facilities at June 30, 2015 is as follows: DP&L Share DPL Carrying value Jointly owned production units and stations: Ownership (%) Summer Production Capacity (MW) Gross Plant in Service ($ in millions) Accumulated Depreciation ($ in millions) Construction Work in Process ($ in millions) SCR and FGD Equipment Installed and in Service (Yes/No) Conesville Unit 4 16.5 129 $ 25 $ 3 $ 1 Yes Killen Station 67.0 402 339 25 1 Yes Miami Fort Units 7 and 8 36.0 368 218 28 4 Yes Stuart Station 35.0 808 234 19 11 Yes Zimmer Station 28.1 371 186 40 4 Yes Transmission (at varying percentages) n/a 42 7 — Total 2,078 $ 1,044 $ 122 $ 21 DPL revalued DP&L’s investment in the above plants at the estimated fair value for each plant at the date of the Merger.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership of Coal-fired Facilities	Ownership of Coal-fired Facilities DP&L has undivided ownership interests in five coal-fired electric generating facilities, various peaking facilities and numerous transmission facilities with certain other Ohio utilities. Certain expenses, primarily fuel costs for the generating units, are allocated to the owners based on the energy taken. The remaining expenses, investments in fuel inventory, plant materials and operating supplies, and capital additions are allocated to the owners in accordance with their respective ownership interests. At June 30, 2015 , DP&L had $21.0 million of construction work in process at such jointly owned facilities. DP&L’s share of the operating cost of such facilities is included within the corresponding line in the Condensed Statements of Operations and DP&L’s share of the investment in the facilities is included within Total net property, plant & equipment in the Condensed Balance Sheets. Each joint owner provides their own financing for their share of the operations and capital expenditures of the jointly owned unit or station. DP&L’s undivided ownership interest in such facilities at June 30, 2015 , is as follows: DP&L Share DP&L Carrying value Jointly owned production units and stations: Ownership (%) Summer Production Capacity (MW) Gross Plant in Service ($ in millions) Accumulated Depreciation ($ in millions) Construction Work in Process ($ in millions) SCR and FGD Equipment Installed and in Service (Yes/No) Conesville Unit 4 16.5 129 $ 25 $ 6 $ 1 Yes Killen Station 67.0 402 654 321 1 Yes Miami Fort Units 7 and 8 36.0 368 366 167 4 Yes Stuart Station 35.0 808 771 331 11 Yes Zimmer Station 28.1 371 1,104 683 4 Yes Transmission (at varying percentages) n/a 98 63 — Total 2,078 $ 3,018 $ 1,571 $ 21

Debt Obligations

Debt Obligations	6 Months Ended
	Jun. 30, 2015
Debt Instrument [Line Items]
Debt Obligations	Debt Obligations Long-term debt June 30, December 31, $ in millions 2015 2014 First mortgage bonds due in September 2016 - 1.875% $ 445.0 $ 445.0 Pollution control series due in January 2028 - 4.7% — 35.3 Pollution control series due in January 2034 - 4.8% 100.0 179.1 Pollution control series due in September 2036 - 4.8% 100.0 100.0 Pollution control series due in November 2040 - rates from: 0.02% - 0.12% and 0.04% - 0.15% (a) 100.0 100.0 U.S. Government note due in February 2061 - 4.2% 18.0 18.1 Unamortized debt discount / premiums, net (2.7 ) (2.8 ) Total long-term debt at subsidiary 760.3 874.7 Bank term loan due in May 2018 - rates from: 2.41% - 2.44% and 2.42% - 2.45% (a) 125.0 140.0 Senior unsecured bonds due in October 2016 - 6.5% 130.0 130.0 Senior unsecured bonds due in October 2019 - 6.75% 200.0 200.0 Senior unsecured bonds due in October 2021 - 7.25% 780.0 780.0 Note to DPL Capital Trust II due in September 2031 - 8.125% (b) 15.6 15.6 Unamortized debt discount / premiums, net (0.6 ) (0.7 ) Total non-current portion of long-term debt $ 2,010.3 $ 2,139.6 Current portion of long-term debt June 30, December 31, $ in millions 2015 2014 Pollution control series due in January 2028 - 4.7% $ 35.3 $ — Pollution control series due in January 2034 - 4.8% 79.1 — Bank term loan due in May 2018 - rates from: 2.41% - 2.44% and 2.42% - 2.45% (a) 35.0 20.0 U.S. Government note due in February 2061 - 4.2% 0.1 0.1 Total current portion of long-term debt $ 149.5 $ 20.1 (a) Range of interest rates for the six months ended June 30, 2015 and the twelve months ended December 31, 2014 , respectively. (b) Note payable to related party. See Note 1: Related Party Transactions for additional information. Premiums or discounts recognized at the date of the Merger are amortized over the remaining life of the debt using the effective interest method. DP&L has an unsecured revolving credit agreement with a syndicated bank group. Prior to refinancing the facility on July 31, 2015, as discussed below, this facility had a $300.0 million borrowing limit, a five -year term expiring on May 10, 2018, a $100.0 million letter of credit sublimit and a feature that provides DP&L the ability to increase the size of the facility by an additional $100.0 million . At June 30, 2015, there were two letters of credit in the amount of $1.4 million outstanding, with the remaining $298.6 million available to DP&L . Fees associated with this letter of credit facility were not material during the six months ended June 30, 2015 or 2014. As discussed below, this agreement was refinanced in July 2015. DP&L’s unsecured revolving credit agreement and DP&L’s amended standby letters of credit have two financial covenants. The first financial covenant measures Total Debt to Total Capitalization. The Total Debt to Total Capitalization ratio is calculated, at the end of each fiscal quarter, by dividing total debt at the end of the quarter by total capitalization at the end of the quarter. The second financial covenant ratio compares EBITDA to Interest Expense ratio. The EBITDA to Interest Expense ratio is calculated, at the end of each fiscal quarter, by dividing EBITDA for the four prior fiscal quarters by the consolidated interest charges for the same period. The above covenants were retained with some amendments in DP&L's revolving credit facility refinanced on July 31, 2015 discussed below. The DP&L amended standby letter of credit facilities were terminated on August 3, 2015. On July 1, 2015, the $35.3 million of DP&L's 4.7% pollution control bonds due January 2028 and $41.3 million of DP&L's 4.8% pollution control bonds due January of 2034 were called at par and were redeemed with cash. On July 31, 2015, DP&L refinanced its revolving credit facility, reducing the total size from $300.0 million to $175.0 million , with a $50.0 million letter of credit sublimit and a feature that provides DP&L the ability to increase the size of the facility by an additional $100.0 million . This refinancing extended the life of the facility from May 2018 to July 2020. On August 3, 2015, DP&L called $100.0 million of variable rate pollution control bonds due November 2040 and $137.8 million of 4.8% pollution control bonds due January of 2034. These bonds were refinanced with $200.0 million of new pollution control bonds at variable rates of interest secured by first mortgage bonds in an equivalent amount, and the remaining $37.8 million was redeemed with cash on hand and a draw from the DP&L revolving line of credit. As a result of these transactions, $35.3 million , $41.3 million and $37.8 million (total of $114.4 million ) of long-term DP&L debt was reclassified to current as of June 30, 2015 as reflected in the tables above. DPL has a revolving credit facility. This facility has a letter of credit sublimit and a feature that provides DPL the ability to increase the size of the facility. Prior to refinancing the facility on July 31, 2015, as discussed below, this facility was unsecured and had a borrowing limit of $100.0 million with a $100.0 million letter of credit sublimit, was able to be increased in size by DPL by an additional $50.0 million and had a five -year term expiring on May 10, 2018; with a springing maturity, meaning that if DPL had not refinanced its senior unsecured bonds due October 2016 before July 15, 2016, then the maturity of this facility would have been July 15, 2016. At June 30, 2015, there was one letter of credit in the amount of $2.3 million outstanding, with the remaining $97.7 million available to DPL . Fees associated with this facility were not material during the six months ended June 30, 2015 or 2014. As discussed below, this facility was refinanced in July 2015. On July 31, 2015, DPL refinanced its revolving credit facility, increasing the total size from $100.0 million to $205.0 million , with a $200.0 million letter of credit sublimit and a feature that provides DPL the ability, under certain circumstances, to increase the size of the facility by an additional $95.0 million . This facility is secured by a pledge of common stock that DPL owns in DP&L , limited to the amount permitted to be pledged under certain Indentures dated October 3, 2011 and October 6, 2014 between DPL and Wells Fargo Bank, NA and U.S. Bank National Association, respectively, as Trustee and a limited recourse guarantee by DPLE secured by assets of DPLE. This refinancing extended the life of the facility from May 2018 to July 2020. DPL's new credit facility has a springing maturity feature providing that if, before July 1, 2019, DPL has not refinanced its senior unsecured bonds due October 2019 to have a maturity date that is at least six months later than July 31, 2020, then the maturity of this facility shall be July 1, 2019. At the same time, DPL refinanced its term loan paying down the outstanding amount from $160.0 million to $125.0 million , extending the term to July of 2020, pushing back required principal payments to 2017, and providing a mechanism for DPL to request additional term loans to refinance existing indebtedness. This facility is secured by a pledge of common stock that DPL owns in DP&L , limited to the amount permitted to be pledged under certain Indentures dated October 3, 2011 and October 6, 2014 between DPL and Wells Fargo Bank, NA and U.S. Bank National Association, respectively, as Trustee and a limited recourse guarantee by DPLE secured by assets of DPLE. The new term loan has a springing maturity feature providing that if, before July 1, 2019, DPL has not refinanced its senior unsecured bonds due October 2019 to have a maturity date that is at least six months later than July 31, 2020, then the maturity of this facility shall be July 1, 2019. As a result of this refinancing, the portion of the term loan that is classified as current ( $35.0 million ) was redeemed with cash. DPL’s revolving credit agreement and term loan have two financial covenants. The first financial covenant, a Total Debt to EBITDA ratio, is calculated at the end of each fiscal quarter by dividing total debt at the end of the current quarter by consolidated EBITDA for the four prior fiscal quarters. The second financial covenant, an EBITDA to Interest Expense ratio, is calculated, at the end of each fiscal quarter, by dividing EBITDA for the four prior fiscal quarters by the consolidated interest charges for the same period. The above covenants were retained with some amendments in DPL's revolving credit facility refinanced on July 31, 2015. DPL’s revolving credit agreement and term loan restrict dividend payments from DPL to AES and adjust the cost of borrowing under the facilities under certain credit rating scenarios. Substantially all property, plant & equipment of DP&L is subject to the lien of the mortgage securing DP&L’s First and Refunding Mortgage.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt Obligations	Debt Obligations Long-term debt June 30, December 31, $ in millions 2015 2014 First mortgage bonds due in September 2016 - 1.875% $ 445.0 $ 445.0 Pollution control series due in January 2028 - 4.7% — 35.3 Pollution control series due in January 2034 - 4.8% 100.0 179.1 Pollution control series due in September 2036 - 4.8% 100.0 100.0 Pollution control series due in November 2040 - rates from: 0.02% - 0.12% and 0.04% - 0.15% (a) 100.0 100.0 U.S. Government note due in February 2061 - 4.2% 18.0 18.1 Unamortized debt discount (0.3 ) (0.5 ) Total non-current portion of long-term debt $ 762.7 $ 877.0 Current portion of long-term debt June 30, December 31, $ in millions 2015 2014 Pollution control series due in January 2028 - 4.7% $ 35.3 $ — Pollution control series due in January 2034 - 4.8% 79.1 — U.S. Government note due in February 2061 - 4.2% 0.1 0.1 Total current portion of long-term debt $ 114.5 $ 0.1 (a) Range of interest rates for the six months ended June 30, 2015 and the twelve months ended December 31, 2014 , respectively. DP&L has an unsecured revolving credit agreement with a syndicated bank group. Prior to refinancing the facility on July 31, 2015, as discussed below, this facility had a $300.0 million borrowing limit, a five -year term expiring on May 10, 2018, a $100.0 million letter of credit sublimit and a feature that provides DP&L the ability to increase the size of the facility by an additional $100.0 million . At June 30, 2015, there were two letters of credit in the amount of $1.4 million outstanding, with the remaining $298.6 million available to DP&L . Fees associated with this letter of credit facility were not material during the six months ended June 30, 2015 or 2014. As discussed below, this agreement was refinanced in July 2015. On July 1, 2015, the $35.3 million of 4.7% pollution control bonds due January 2028 and $41.3 million of the 4.8% pollution control bonds due January of 2034 became callable at par and were redeemed with cash. On July 31, 2015, DP&L refinanced its revolving credit facility, reducing the total size from $300.0 million to $175.0 million , with a $50.0 million letter of credit sublimit and a feature that provides DP&L the ability to increase the size of the facility by an additional $100.0 million . This refinancing extended the life of the facility from May 2018 to July 2020. On August 3, 2015, DP&L called $100.0 million of variable rate pollution control bonds due November 2040 and $137.8 million of 4.8% pollution control bonds due January of 2034. These bonds were refinanced with $200.0 million of new pollution control bonds at variable rates of interest secured by first mortgage bonds in an equivalent amount and the remaining $37.8 million of these bonds were redeemed with cash on hand and a draw from the DP&L revolving line of credit. As a result of these transactions, $35.3 million , $41.3 million and $37.8 million (total of $114.4 million ) of long-term debt was reclassified to current as of June 30, 2015 as reflected in the tables above. DP&L’s unsecured revolving credit agreements and DP&L’s standby letter of credit have two financial covenants. The first financial covenant measures Total Debt to Total Capitalization. The Total Debt to Total Capitalization ratio is calculated, at the end of each fiscal quarter, by dividing total debt at the end of the quarter by total capitalization at the end of the quarter. The second financial covenant compares EBITDA to Interest Expense. The EBITDA to Interest Expense ratio is calculated, at the end of each fiscal quarter, by dividing EBITDA for the four prior fiscal quarters by the consolidated interest charges for the same period. The above covenants were retained with some amendments in DP&L's revolving credit facility refinanced on July 31, 2015. The DP&L amended standby letter of credit facilities were terminated on August 3, 2015. Substantially all property, plant & equipment of DP&L is subject to the lien of the mortgage securing DP&L’s First and Refunding Mortgage.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2015
Income Taxes	Income Taxes The following table details the effective tax rates for the three and six months ended June 30, 2015 and 2014 . Three months ended Six months ended June 30, June 30, 2015 2014 2015 2014 DPL 2.2% (4.8)% 20.7% (49.0)% Income tax expense for the six months ended June 30, 2015 and 2014 was calculated using the estimated annual effective income tax rates for 2015 and 2014 of 31.2% and (49.0)% , respectively. For the six months ended June 30, 2015 and 2014 , management estimated the annual effective tax rate based on its forecast of annual pre-tax income. To the extent that actual pre-tax results for the year differ from the forecasts applied to the most recent interim period, the rates estimated could be materially different from the actual effective tax rates. For the three and six months ended June 30, 2015 , DPL’s current period effective rate was less than the estimated annual effective rate primarily due to the sale of MC Squared. The increase in the effective rate compared to the same period in 2014 is primarily due to the non-deductible goodwill impairment in 2014 which did not occur in 2015.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Income Taxes	Income Taxes The following table details the effective tax rates for the three and six months ended June 30, 2015 and 2014 . Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 DP&L 27.9% 30.2% 28.5% 29.9% Income tax expense for the three and six months ended June 30, 2015 and 2014 was calculated using the estimated annual effective income tax rates for 2015 and 2014 of 29.4% and 30.4% , respectively. For the three and six months ended June 30, 2015 and 2014 management estimated the annual effective tax rate based on its forecast of annual pre-tax income. To the extent that actual pre-tax results for the year differ from the forecasts applied to the most recent interim period, the rates estimated could be materially different from the actual effective tax rates. For the three and six months ended June 30, 2015 , DP&L’s current period effective rate is less than the estimated annual effective rate due to the deduction for the preferred stock dividends and other immaterial adjustments.

Pension and Postretirement Bene

Pension and Postretirement Benefits	6 Months Ended
	Jun. 30, 2015
Pension and Postretirement Benefits	Pension and Postretirement Benefits DP&L sponsors a defined benefit pension plan for the vast majority of its employees. We generally fund pension plan benefits as accrued in accordance with the minimum funding requirements of ERISA and, in addition, make voluntary contributions from time to time. There were no contributions made during the six months ended June 30, 2015 or 2014 . The amounts presented in the following tables for pension include the collective bargaining plan formula, the traditional management plan formula, the cash balance plan formula and the SERP, in the aggregate. The amounts presented for postretirement include both health and life insurance. The pension and postretirement costs below have not been adjusted for amounts billed to the Service Company for former DP&L employees who are now employed by the Service Company but are still participants in the DP&L plan. See "Related Party Transactions" discussion in Note 1, "Overview and Summary of Significant Accounting Policies". The net periodic benefit cost of the pension and postretirement benefit plans for the three and six months ended June 30, 2015 and 2014 was: Net Periodic Benefit Cost Pension Postretirement Three months ended Three months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Service cost $ 1.8 $ 1.5 $ — $ — Interest cost 4.3 4.4 0.1 0.2 Expected return on plan assets (5.6 ) (5.6 ) — — Amortization of unrecognized: Prior service cost 0.5 0.3 — — Actuarial loss / (gain) 1.4 0.8 (0.1 ) (0.2 ) Net periodic benefit cost $ 2.4 $ 1.4 $ — $ — Net Periodic Benefit Cost Pension Postretirement Six months ended Six months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Service cost $ 3.6 $ 3.0 $ — $ 0.1 Interest cost 8.6 8.8 0.3 0.4 Expected return on plan assets (11.3 ) (11.4 ) — (0.1 ) Amortization of unrecognized: Prior service cost 1.0 0.7 — — Actuarial loss / (gain) 2.9 1.7 (0.2 ) (0.3 ) Net periodic benefit cost $ 4.8 $ 2.8 $ 0.1 $ 0.1 Benefit payments and Medicare Part D reimbursements, which reflect future service, are estimated to be paid as follows: $ in millions Pension Postretirement 2015 $ 12.4 $ 0.9 2016 25.2 1.8 2017 25.7 1.7 2018 26.3 1.6 2019 26.7 1.5 2020 - 2024 137.0 6.1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Pension and Postretirement Benefits	Pension and Postretirement Benefits DP&L sponsors a defined benefit pension plan for the vast majority of its employees. We generally fund pension plan benefits as accrued in accordance with the minimum funding requirements of ERISA and, in addition, make voluntary contributions from time to time. There were no contributions made during the six months ended June 30, 2015 or 2014 . The amounts presented in the following tables for pension include the collective bargaining plan formula, the traditional management plan formula, the cash balance plan formula and the SERP, in the aggregate. The amounts presented for postretirement include both health and life insurance. The pension and postretirement costs below have not been adjusted for amounts billed to the Service Company for former DP&L employees who are now employed by the Service Company but are still participants in the DP&L plan. See "Related Party Transactions" discussion in Note 1, "Overview and Summary of Significant Accounting Policies". The net periodic benefit cost of the pension and postretirement benefit plans for the three and six months ended June 30, 2015 and 2014 was: Net Periodic Benefit Cost Pension Postretirement Three months ended Three months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Service cost $ 1.7 $ 1.4 $ — $ 0.1 Interest cost 4.3 4.3 0.2 0.2 Expected return on plan assets (5.5 ) (5.6 ) — (0.1 ) Amortization of unrecognized: Prior service cost 0.8 0.7 — — Actuarial loss / (gain) 2.4 1.6 (0.1 ) (0.1 ) Net periodic benefit cost $ 3.7 $ 2.4 $ 0.1 $ 0.1 Net Periodic Benefit Cost Pension Postretirement Six months ended Six months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Service cost $ 3.5 $ 2.9 $ — $ 0.1 Interest cost 8.6 8.7 0.4 0.4 Expected return on plan assets (11.2 ) (11.3 ) — (0.1 ) Amortization of unrecognized: Prior service cost 1.6 1.4 — — Actuarial loss / (gain) 4.8 3.2 (0.3 ) (0.3 ) Net periodic benefit cost $ 7.3 $ 4.9 $ 0.1 $ 0.1 Benefit payments and Medicare Part D reimbursements, which reflect future service, are estimated to be paid as follows: $ in millions Pension Postretirement 2015 $ 12.4 $ 0.9 2016 25.2 1.8 2017 25.7 1.7 2018 26.3 1.6 2019 26.7 1.5 2020 - 2024 137.0 6.1

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	Fair Value Measurements The fair values of our financial instruments are based on published sources for pricing when possible. We rely on valuation models only when no other methods exist. The value of our financial instruments represents our best estimates of the fair value, which may not be the value realized in the future. The following table presents the fair value and cost of our non-derivative instruments at June 30, 2015 and December 31, 2014 . Information about the fair value of our derivative instruments can be found in Note 9. June 30, 2015 December 31, 2014 $ in millions Carrying Value Fair Value Carrying Value Fair Value Assets Money market funds $ 0.2 $ 0.2 $ 0.1 $ 0.1 Equity securities 2.7 3.7 2.7 3.7 Debt securities 4.5 4.5 4.7 4.7 Hedge funds 0.6 0.7 0.8 0.8 Real estate 0.3 0.3 0.4 0.4 Total Assets $ 8.3 $ 9.4 $ 8.7 $ 9.7 Liabilities Debt $ 2,159.8 $ 2,235.3 $ 2,159.7 $ 2,204.8 These financial instruments are not subject to master netting agreements or collateral requirements and as such are presented in the Condensed Consolidated Balance Sheet at their gross fair value, except for Debt, which is presented at amortized carrying value. Debt Unrealized gains or losses are not recognized in the financial statements as debt is presented at the carrying value, net of unamortized premium or discount in the financial statements. The debt amounts include the current portion payable in the next twelve months and have maturities that range from 2016 to 2061 . Master Trust Assets DP&L established Master Trusts to hold assets that could be used for the benefit of employees participating in employee benefit plans and these assets are not used for general operating purposes. These assets are primarily comprised of open-ended mutual funds, which are valued using the net asset value per unit. These investments are recorded at fair value within Other deferred assets on the balance sheets and classified as available-for-sale. Any unrealized gains or losses are recorded in AOCI until the securities are sold. DPL had $0.9 million ( $0.6 million after tax) and $0.8 million ( $0.5 million after tax) of unrealized gains and immaterial unrealized losses on the Master Trust assets in AOCI at June 30, 2015 and at December 31, 2014 , respectively. During the six months ended June 30, 2015 , $0.6 million ( $0.4 million after tax) of various investments were sold to facilitate the distribution of benefits and the unrealized gains were reversed into earnings. An immaterial amount of unrealized gains are expected to be reversed to earnings over the next twelve months to facilitate the distribution of benefits. Fair Value Hierarchy Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. These inputs are then categorized as: • Level 1 (quoted prices in active markets for identical assets or liabilities); • Level 2 (observable inputs such as quoted prices for similar assets or liabilities or quoted prices in markets that are not active); • Level 3 (unobservable inputs). Valuations of assets and liabilities reflect the value of the instrument including the values associated with counterparty risk. We include our own credit risk and our counterparty’s credit risk in our calculation of fair value using global average default rates based on an annual study conducted by a large rating agency. We did not have any transfers of the fair values of our financial instruments between Level 1 and Level 2 of the fair value hierarchy during the three months and six months ended June 30, 2015 and 2014 . The fair value of assets and liabilities at June 30, 2015 and December 31, 2014 and the respective category within the fair value hierarchy for DPL was determined as follows: Assets and Liabilities at Fair Value Level 1 Level 2 Level 3 $ in millions Fair value at June 30, 2015 Based on Quoted Prices in Active Markets Other Observable Inputs Unobservable Inputs Assets Master Trust assets Money market funds $ 0.2 $ 0.2 $ — $ — Equity securities 3.7 — 3.7 — Debt securities 4.5 — 4.5 — Hedge funds 0.7 — 0.7 — Real estate 0.3 — 0.3 — Total Master Trust assets 9.4 0.2 9.2 — Derivative Assets FTRs 0.4 — — 0.4 Forward power contracts 19.3 — 18.8 0.5 Total Derivative assets 19.7 — 18.8 0.9 Total Assets $ 29.1 $ 0.2 $ 28.0 $ 0.9 Liabilities Derivative Liabilities Heating oil 0.1 0.1 — — FTRs 0.9 — — 0.9 Forward power contracts 17.7 — 17.7 — Total Derivative liabilities 18.7 0.1 17.7 0.9 Debt 2,235.3 — 2,217.3 18.0 Total Liabilities $ 2,254.0 $ 0.1 $ 2,235.0 $ 18.9 Assets and Liabilities at Fair Value Level 1 Level 2 Level 3 $ in millions Fair value at December 31, 2014 Based on Quoted Prices in Active Markets Other Observable Inputs Unobservable Inputs Assets Master Trust assets Money market funds $ 0.1 $ 0.1 $ — $ — Equity securities 3.7 — 3.7 — Debt securities 4.7 — 4.7 — Hedge funds 0.8 — 0.8 — Real estate 0.4 — 0.4 — Total Master Trust assets 9.7 0.1 9.6 — Derivative assets Forward power contracts 14.9 — 13.7 1.2 Total Derivative assets 14.9 — 13.7 1.2 Total Assets $ 24.6 $ 0.1 $ 23.3 $ 1.2 Liabilities Derivative liabilities FTRs $ 0.6 $ — $ — 0.6 Heating oil futures 0.4 0.4 — — Natural gas futures 0.1 0.1 — — Forward power contracts 11.1 — 11.1 — Total Derivative liabilities 12.2 0.5 11.1 0.6 Debt 2,204.8 — 2,186.6 18.2 Total Liabilities $ 2,217.0 $ 0.5 $ 2,197.7 $ 18.8 Our financial instruments are valued using the market approach in the following categories: • Level 1 inputs are used for derivative contracts such as heating oil futures and for money market accounts that are considered cash equivalents. The fair value is determined by reference to quoted market prices and other relevant information generated by market transactions. • Level 2 inputs are used to value derivatives such as forward power contracts (which are traded on the OTC market but which are valued using prices on the NYMEX for similar contracts on the OTC market). Other Level 2 assets include open-ended mutual funds that are in the Master Trust, which are valued using observable prices based on the end of day NAV per unit. • Level 3 inputs such as FTRs are considered a Level 3 input because the monthly auctions are considered inactive. Other Level 3 inputs include the credit valuation adjustment on some of the forward power contracts and forward power contracts in less active markets. Our Level 3 inputs are immaterial to our derivative balances as a whole and as such no further disclosures are presented. Approximately 96% of the inputs to the fair value of our derivative instruments are from quoted market prices. Our debt is fair valued for disclosure purposes only and most of the fair values are determined using quoted market prices in inactive markets. These fair value inputs are considered Level 2 in the fair value hierarchy. As the Wright-Patterson Air Force Base loan is not publicly traded, fair value is assumed to equal carrying value. These fair value inputs are considered Level 3 in the fair value hierarchy as there are no observable inputs. Additional Level 3 disclosures are not presented since debt is not recorded at fair value. Non-recurring Fair Value Measurements We use the cost approach to determine the fair value of our AROs, which is estimated by discounting expected cash outflows to their present value at the initial recording of the liability. Cash outflows are based on the approximate future disposal cost as determined by market information, historical information or other management estimates. These inputs to the fair value of the AROs would be considered Level 3 inputs under the fair value hierarchy. AROs for ash ponds, asbestos, river structures and underground storage tanks increased by $39.8 million and $1.2 million during the six months ended June 30, 2015 and 2014 , respectively. The majority of the increase in 2015 is due to an increase in the AROs for ash ponds ( $40.6 million ) as a result of new rules promulgated by the USEPA that were published in the Federal Register in April 2015 and will become effective in October 2015. When evaluating impairment of goodwill and long-lived assets, we measure fair value using the applicable fair value measurement guidance. Impairment expense is measured by comparing the fair value at the evaluation date to the carrying amount. The following table summarizes Goodwill and Long-lived assets measured at fair value on a non-recurring basis during the period and their level within the fair value hierarchy (there were no impairments during the six months ended June 30, 2015 ): $ in millions Six months ended June 30, 2014 Carrying Fair Value Gross Amount (c) Level 1 Level 2 Level 3 Loss Assets Long-lived assets (a) DP&L (East Bend) $ 14.2 $ — $ — $ 2.7 $ 11.5 Goodwill (b) DPLER Reporting unit $ 135.8 $ — $ — $ — $ 135.8 (a) See Note 13 for further information (b) See Note 12 for further information (c) Carrying amount at date of valuation
THE DAYTON POWER AND LIGHT COMPANY [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurements	Fair Value Measurements The fair values of our financial instruments are based on published sources for pricing when possible. We rely on valuation models only when no other method is available to us. The value of our financial instruments represents our best estimates of fair value, which may not be the value realized in the future. The following table presents the fair value and cost of our non-derivative instruments at June 30, 2015 and December 31, 2014 . Information about the fair value of our derivative instruments can be found in Note 9. June 30, 2015 December 31, 2014 $ in millions Carrying Value Fair Value Carrying Value Fair Value Assets Money market funds $ 0.2 $ 0.2 $ 0.1 $ 0.1 Equity securities 2.7 3.7 2.7 3.7 Debt securities 4.5 4.5 4.7 4.7 Hedge funds 0.6 0.7 0.8 0.8 Real estate 0.3 0.3 0.4 0.4 Total assets $ 8.3 $ 9.4 $ 8.7 $ 9.7 Liabilities Debt $ 877.2 $ 883.1 $ 877.1 $ 882.5 These financial instruments are not subject to master netting agreements or collateral requirements and as such are presented in the Condensed Balance Sheet at their gross fair value, except for Debt, which is presented at amortized cost. Debt Unrealized gains or losses are not recognized in the financial statements as debt is presented at the carrying value, net of unamortized premium or discount in the financial statements. The debt amounts include the current portion payable in the next twelve months and have maturities that range from 2016 to 2061 . Master Trust Assets DP&L established Master Trusts to hold assets that could be used for the benefit of employees participating in employee benefit plans and these assets are not used for general operating purposes. These assets are primarily comprised of open-ended mutual funds that are valued using the net asset value per unit. These investments are recorded at fair value within Other deferred assets on the balance sheets and classified as available-for-sale. Any unrealized gains or losses are recorded in AOCI until the securities are sold. DP&L had $1.0 million ( $0.6 million after tax) and $1.1 million ( $0.7 million after tax) in unrealized gains and immaterial unrealized losses on the Master Trust assets in AOCI at June 30, 2015 and at December 31, 2014 , respectively. During the six months ended June 30, 2015 , $0.6 million ( $0.4 million after tax) of various investments were sold to facilitate the distribution of benefits and the unrealized gains were reversed into earnings. An immaterial amount of unrealized gains are expected to be reversed to earnings over the next twelve months to facilitate the disbursement of benefits. Fair Value Hierarchy Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. These inputs are then categorized as: • Level 1 (quoted prices in active markets for identical assets or liabilities); • Level 2 (observable inputs such as quoted prices for similar assets or liabilities or quoted prices in markets that are not active); • Level 3 (unobservable inputs). Valuations of assets and liabilities reflect the value of the instrument including the values associated with counterparty risk. We include our own credit risk and our counterparty’s credit risk in our calculation of fair value using global average default rates based on an annual study conducted by a large rating agency. We did not have any transfers of the fair values of our financial instruments between Level 1 and Level 2 of the fair value hierarchy during the three months and six months ended June 30, 2015 and 2014. The fair value of assets and liabilities at June 30, 2015 and December 31, 2014 and the respective category within the fair value hierarchy for DP&L was determined as follows: Assets and Liabilities at Fair Value Level 1 Level 2 Level 3 $ in millions Fair value at June 30, 2015 Based on Quoted Prices in Active Markets Other Observable Inputs Unobservable Inputs Assets Master Trust assets Money market funds $ 0.2 $ 0.2 $ — $ — Equity securities 3.7 — 3.7 — Debt securities 4.5 — 4.5 — Hedge funds 0.7 — 0.7 — Real estate 0.3 — 0.3 — Total Master Trust assets 9.4 0.2 9.2 — Derivative assets FTRs 0.4 — — 0.4 Forward power contracts 19.5 — 19.0 0.5 Total derivative assets 19.9 — 19.0 0.9 Total assets $ 29.3 $ 0.2 $ 28.2 $ 0.9 Liabilities Derivative liabilities Heating oil $ 0.1 $ 0.1 $ — $ — FTRs 0.9 — — 0.9 Forward power contracts 17.9 — 17.9 — Total derivative liabilities 18.9 0.1 17.9 0.9 Debt 883.1 — 865.1 18.0 Total liabilities $ 902.0 $ 0.1 $ 883.0 $ 18.9 Assets and Liabilities at Fair Value Level 1 Level 2 Level 3 $ in millions Fair value at December 31, 2014 Based on Quoted Prices in Active Markets Other Observable Inputs Unobservable Inputs Assets Master Trust assets Money market funds $ 0.1 $ 0.1 $ — $ — Equity securities 3.7 — 3.7 — Debt securities 4.7 — 4.7 — Hedge funds 0.8 — 0.8 — Real estate 0.4 — 0.4 — Total Master Trust assets 9.7 0.1 9.6 — Derivative assets Forward power contracts 15.1 — 13.9 1.2 Total Derivative assets 15.1 — 13.9 1.2 Total assets $ 24.8 $ 0.1 $ 23.5 $ 1.2 Liabilities Derivative liabilities FTRs $ 0.6 $ — $ — $ 0.6 Heating oil futures 0.4 0.4 — — Natural gas futures 0.1 0.1 — — Forward power contracts 11.2 — 11.2 — Total Derivative liabilities 12.3 0.5 11.2 0.6 Debt 882.5 — 864.3 18.2 Total liabilities $ 894.8 $ 0.5 $ 875.5 $ 18.8 Our financial instruments are valued using the market approach in the following categories: • Level 1 inputs are used for derivative contracts such as heating oil futures and for money market accounts that are considered cash equivalents. The fair value is determined by reference to quoted market prices and other relevant information generated by market transactions. • Level 2 inputs are used to value derivatives such as forward power contracts (which are traded on the OTC market but which are valued using prices on the NYMEX for similar contracts on the OTC market). Other Level 2 assets include open-ended mutual funds that are in the Master Trust, which are valued using observable prices based on the end of day NAV per unit. • Level 3 inputs such as FTRs are considered a Level 3 input because the monthly auctions are considered inactive. Our Level 3 inputs are immaterial to our derivative balances as a whole and as such no further disclosures are presented. Our debt is fair valued for disclosure purposes only and most of the fair values are determined using quoted market prices in inactive markets. These fair value inputs are considered Level 2 in the fair value hierarchy. Since the Wright-Patterson Air Force Base loan is not publicly traded, fair value is assumed to equal carrying value. These fair value inputs are considered Level 3 in the fair value hierarchy as there are no observable inputs. Additional Level 3 disclosures are not presented since debt is not recorded at fair value. Approximately 96% of the inputs to the fair value of our derivative instruments are from quoted market prices. Non-recurring Fair Value Measurements We use the cost approach to determine the fair value of our AROs, which is estimated by discounting expected cash outflows to their present value at the initial recording of the liability. Cash outflows are based on the approximate future disposal cost as determined by market information, historical information or other management estimates. AROs for ash ponds, asbestos, river structures and underground storage tanks increased by $39.8 million and $1.2 million during the six months ended June 30, 2015 and 2014 , respectively. The majority of the increase in 2015 is due to an increase in the AROs for ash ponds ( $40.6 million ) due to new rules promulgated by the USEPA that were published in the Federal Register in April 2015 and will become effective in October 2015.

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities In the normal course of business, DPL enters into various financial instruments, including derivative financial instruments. We use derivatives principally to manage the risk of changes in market prices for commodities. The derivatives that we use to economically hedge these risks are governed by our risk management policies for forward and futures contracts. Our net positions are continually assessed within our structured hedging programs to determine whether new or offsetting transactions are required. The objective of the hedging program is to mitigate financial risks while ensuring that we have adequate resources to meet our requirements. We monitor and value derivative positions monthly as part of our risk management processes. We use published sources for pricing, when possible, to mark positions to market. All of our derivative instruments are used for risk management purposes and are designated as normal purchase/normal sale, cash flow hedges or marked to market each reporting period. At June 30, 2015 , DPL had the following outstanding derivative instruments: Commodity Accounting Treatment Unit Purchases (in thousands) Sales (in thousands) Net Purchases/ (Sales) (in thousands) FTRs Mark to Market MWh 24.2 — 24.2 Heating oil futures Mark to Market Gallons 168.0 — 168.0 Forward power contracts Cash Flow Hedge MWh 1,723.4 (8,809.4 ) (7,086.0 ) Forward power contracts Mark to Market MWh 3,621.9 (3,530.4 ) 91.5 At December 31, 2014 , DPL had the following outstanding derivative instruments: Commodity Accounting Treatment Unit Purchases (in thousands) Sales (in thousands) Net Purchases/ (Sales) (in thousands) FTRs Mark to Market MWh 10.5 — 10.5 Heating oil futures Mark to Market Gallons 378.0 — 378.0 Natural gas futures Mark to Market Dths 200.0 — 200.0 Forward power contracts Cash Flow Hedge MWh 175.0 (2,991.0 ) (2,816.0 ) Forward power contracts Mark to Market MWh 1,725.2 (2,707.8 ) (982.6 ) Cash Flow Hedges As part of our risk management processes, we identify the relationships between hedging instruments and hedged items, as well as the risk management objective and strategy for undertaking various hedge transactions. The fair value of cash flow hedges is determined by observable market prices available as of the balance sheet dates and will continue to fluctuate with changes in market prices up to contract expiration. The effective portion of the hedging transaction is recognized in AOCI and transferred to earnings using specific identification of each contract when the forecasted hedged transaction takes place or when the forecasted hedged transaction is probable of not occurring. The ineffective portion of the cash flow hedge is recognized in earnings in the current period. All risk components were taken into account to determine the hedge effectiveness of the cash flow hedges. We enter into forward power contracts to manage commodity price risk exposure related to our generation of electricity. We do not hedge all commodity price risk. We reclassify gains and losses on forward power contracts from AOCI into earnings in those periods in which the contracts settle. The following table provides information for DPL concerning gains or losses recognized in AOCI for the cash flow hedges for the three months ended June 30, 2015 and 2014 : Three months ended Three months ended June 30, 2015 June 30, 2014 Interest Interest $ in millions (net of tax) Power Rate Hedge Power Rate Hedge Beginning accumulated derivative gain / (loss) in AOCI $ 1.0 $ 18.2 $ (5.7 ) $ 18.9 Net gains / (losses) associated with current period hedging transactions 1.7 — (12.1 ) — Net gains / (losses) reclassified to earnings Interest expense — (0.4 ) — (0.1 ) Revenues (1.9 ) — 5.5 — Purchased power 0.3 — (0.1 ) — Ending accumulated derivative gain / (loss) in AOCI $ 1.1 $ 17.8 $ (12.4 ) $ 18.8 The following table provides information for DPL concerning gains or losses recognized in AOCI for the cash flow hedges for the six months ended June 30, 2015 and 2014 : Six months ended Six months ended June 30, 2015 June 30, 2014 Interest Interest $ in millions (net of tax) Power Rate Hedge Power Rate Hedge Beginning accumulated derivative gain in AOCI $ 0.2 $ 18.3 $ 1.4 $ 19.2 Net gains / (losses) associated with current period hedging transactions 1.8 — (25.0 ) — Net gains / (losses) reclassified to earnings Interest expense — (0.5 ) — (0.4 ) Revenues (2.1 ) — 12.0 — Purchased power 1.2 — (0.8 ) — Ending accumulated derivative gain / (loss) in AOCI $ 1.1 $ 17.8 $ (12.4 ) $ 18.8 Portion expected to be reclassified to earnings in the next twelve months (a) $ 0.9 $ (0.6 ) Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months) 23 0 (a) The actual amounts that we reclassify from AOCI to earnings related to power can differ from the estimate above due to market price changes. Mark to Market Accounting Certain derivative contracts are entered into on a regular basis as part of our risk management program but do not qualify for hedge accounting or the normal purchase and sales exceptions under FASC 815. Accordingly, such contracts are recorded at fair value with changes in the fair value charged or credited to the Condensed Consolidated Statements of Operations in the period in which the change occurred. This is commonly referred to as “MTM accounting.” Contracts we enter into as part of our risk management program may be settled financially, by physical delivery, or net settled with the counterparty. FTRs, heating oil futures, natural gas, and certain forward power contracts are currently marked to market. Certain qualifying derivative instruments have been designated as normal purchases or normal sales contracts, as provided under GAAP. Derivative contracts that have been designated as normal purchases or normal sales under GAAP are not subject to MTM accounting and are recognized in the Condensed Consolidated Statements of Operations on an accrual basis. Regulatory Assets and Liabilities In accordance with regulatory accounting under GAAP, a cost or loss that is probable of recovery in future rates should be deferred as a regulatory asset and revenue or a gain that is probable of being returned to customers should be deferred as a regulatory liability. Portions of the derivative contracts that are marked to market each reporting period and are related to the retail portion of DP&L’s load requirements are included as part of the fuel and purchased power recovery rider approved by the PUCO which began January 1, 2010. Therefore, the Ohio retail customers’ portion of the heating oil futures is deferred as a regulatory asset or liability until the contracts settle. If these unrealized gains and losses are no longer deemed to be probable of recovery through our rates, they will be reclassified into earnings in the period such determination is made. The following tables present the amount and classification within the Condensed Consolidated Statements of Operations or Condensed Consolidated Balance Sheets of the gains and losses on DPL’s derivatives not designated as hedging instruments for the three and six months ended June 30, 2015 and 2014 : For the three months ended June 30, 2015 $ in millions Heating Oil FTRs Power Total Change in unrealized gain / (loss) $ 0.1 $ (0.8 ) $ 1.2 $ 0.5 Realized loss (0.1 ) — (1.5 ) (1.6 ) Total $ — $ (0.8 ) $ (0.3 ) $ (1.1 ) Recorded in Income Statement: gain / (loss) Purchased power $ — $ (0.8 ) $ (2.8 ) $ (3.6 ) Revenue — — 2.5 2.5 Total $ — $ (0.8 ) $ (0.3 ) $ (1.1 ) For the three months ended June 30, 2014 $ in millions Heating Oil FTRs Power Total Change in unrealized loss $ 0.1 $ (1.2 ) $ 1.8 $ 0.7 Realized gain / (loss) — 0.6 0.5 1.1 Total $ 0.1 $ (0.6 ) $ 2.3 $ 1.8 Recorded in Income Statement: loss Purchased power $ — $ (0.6 ) $ 2.3 $ 1.7 Fuel 0.1 — — 0.1 Total $ 0.1 $ (0.6 ) $ 2.3 $ 1.8 For the six months ended June 30, 2015 $ in millions Heating Oil FTRs Power Natural Gas Total Change in unrealized gain / (loss) $ 0.2 $ 0.1 $ (1.7 ) $ 0.1 $ (1.3 ) Realized loss (0.1 ) (0.1 ) (3.8 ) (0.1 ) (4.1 ) Total $ 0.1 $ — $ (5.5 ) $ — $ (5.4 ) Recorded on Balance Sheet: gain/ (loss) Regulatory Asset $ 0.1 $ — $ — $ — $ 0.1 Recorded in Income Statement: gain / (loss) Purchased power — — (7.7 ) — (7.7 ) Revenue — — 2.2 — 2.2 Total $ 0.1 $ — $ (5.5 ) $ — $ (5.4 ) For the six months ended June 30, 2014 $ in millions Heating Oil FTRs Power Total Change in unrealized loss $ (0.1 ) $ (1.5 ) $ (3.7 ) $ (5.3 ) Realized gain / (loss) 0.1 0.6 (1.5 ) (0.8 ) Total $ — $ (0.9 ) $ (5.2 ) $ (6.1 ) Recorded in Income Statement: loss Purchased power $ — $ (0.9 ) $ (5.2 ) $ (6.1 ) Total $ — $ (0.9 ) $ (5.2 ) $ (6.1 ) DPL has elected not to offset derivative assets and liabilities and not to offset net derivative positions against the right to reclaim cash collateral pledged (an asset) or the obligation to return cash collateral received (a liability) under derivative agreements. The following tables summarize the derivative positions presented in the balance sheet where a right of offset exists under these arrangements and related cash collateral received or pledged. The following table presents the fair value and balance sheet classification of DPL’s derivative instruments at June 30, 2015 : Fair Values of Derivative Instruments at June 30, 2015 Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Consolidated Balance Sheets Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Balance Fair Value Assets Short-term derivative positions (presented in Other current assets) Forward power contracts Cash Flow $ 6.8 $ (4.1 ) $ — $ 2.7 Forward power contracts MTM 4.3 (2.3 ) — 2.0 FTRs MTM 0.4 (0.4 ) — — Long-term derivative positions (presented in Other deferred assets) Forward power contracts Cash Flow 2.7 (1.4 ) — 1.3 Forward power contracts MTM 5.5 (1.4 ) — 4.1 Total assets $ 19.7 $ (9.6 ) $ — $ 10.1 Liabilities Short-term derivative positions (presented in Other current liabilities) Forward power contracts Cash Flow $ 5.3 $ (4.1 ) $ — $ 1.2 Forward power contracts MTM 9.6 (2.3 ) (7.3 ) — Heating oil MTM 0.1 — (0.1 ) — FTRs MTM 0.9 (0.4 ) — 0.5 Long-term derivative positions (presented in Other deferred liabilities) Forward power contracts Cash Flow 1.4 (1.4 ) — — Forward power contracts MTM 1.4 (1.4 ) — — Total liabilities $ 18.7 $ (9.6 ) $ (7.4 ) $ 1.7 The following table presents the fair value and balance sheet classification of DPL’s derivative instruments at December 31, 2014 : Fair Values of Derivative Instruments at December 31, 2014 Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Consolidated Balance Sheets Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Balance Fair Value Assets Short-term derivative positions (presented in Other current assets) Forward power contracts Cash Flow $ 5.6 $ (2.0 ) $ — $ 3.6 Forward power contracts MTM 5.5 (3.4 ) — 2.1 Long-term derivative positions (presented in Other deferred assets) Forward power contracts Cash Flow 0.3 (0.3 ) — — Forward power contracts MTM 3.5 (0.9 ) — 2.6 Total assets $ 14.9 $ (6.6 ) $ — $ 8.3 Liabilities Short-term derivative positions (presented in Other current liabilities) Forward power contracts Cash Flow $ 2.1 $ (2.0 ) $ — $ 0.1 Forward power contracts MTM 7.5 (3.4 ) (4.1 ) — FTRs MTM 0.6 — — 0.6 Heating oil futures MTM 0.4 — (0.4 ) — Natural gas MTM 0.1 — (0.1 ) — Long-term derivative positions (presented in Other deferred liabilities) Forward power contracts Cash Flow 0.6 (0.3 ) (0.3 ) — Forward power contracts MTM 0.9 (0.9 ) — — Total liabilities $ 12.2 $ (6.6 ) $ (4.9 ) $ 0.7 The aggregate fair value of DPL’s commodity derivative instruments that were in a MTM loss position at June 30, 2015 was $18.7 million . $7.4 million of collateral was posted directly with third parties and in a broker margin account which offsets our loss positions on the forward contracts. This liability position is further offset by the asset position of counterparties with master netting agreements of $9.6 million . Since our debt is below investment grade, we could have to post collateral for the remaining $1.7 million .
THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities In the normal course of business, DP&L enters into various financial instruments, including derivative financial instruments. We use derivatives principally to manage the risk of changes in market prices for commodities. The derivatives that we use to economically hedge these risks are governed by our risk management policies for forward and futures contracts. Our net positions are continually assessed within our structured hedging programs to determine whether new or offsetting transactions are required. The objective of the hedging program is to mitigate financial risks while ensuring that we have adequate resources to meet our requirements. We monitor and value derivative positions monthly as part of our risk management processes. We use published sources for pricing, when possible, to mark positions to market. All of our derivative instruments are used for risk management purposes and are designated as cash flow hedges or marked to market each reporting period. At June 30, 2015 , DP&L had the following outstanding derivative instruments: Commodity Accounting Treatment Unit Purchases (in thousands) Sales (in thousands) Net Purchases/ (Sales) (in thousands) FTRs Mark to Market MWh 24.2 — 24.2 Heating oil futures Mark to Market Gallons 168.0 — 168.0 Forward power contracts Cash Flow Hedge MWh 1,723.4 (8,809.4 ) (7,086.0 ) Forward power contracts Mark to Market MWh 3,621.9 (3,606.8 ) 15.1 At December 31, 2014 , DP&L had the following outstanding derivative instruments: Commodity Accounting Treatment Unit Purchases (in thousands) Sales (in thousands) Net Purchases/ (Sales) (in thousands) FTRs Mark to Market MWh 10.5 — 10.5 Heating oil futures Mark to Market Gallons 378.0 — 378.0 Natural Gas Mark to Market Dths 200.0 — 200.0 Forward power contracts Cash Flow Hedge MWh 175.0 (2,991.0 ) (2,816.0 ) Forward power contracts Mark to Market MWh 1,725.2 (2,804.0 ) (1,078.8 ) Cash Flow Hedges As part of our risk management processes, we identify the relationships between hedging instruments and hedged items, as well as the risk management objective and strategy for undertaking various hedge transactions. The fair value of cash flow hedges is determined by observable market prices available as of the balance sheet dates and will continue to fluctuate with changes in market prices up to contract expiration. The effective portion of the hedging transaction is recognized in AOCI and transferred to earnings using specific identification of each contract when the forecasted hedged transaction takes place or when the forecasted hedged transaction is probable of not occurring. The ineffective portion of the cash flow hedge is recognized in earnings in the current period. All risk components were taken into account to determine the hedge effectiveness of the cash flow hedges. We enter into forward power contracts to manage commodity price risk exposure related to our generation of electricity. We do not hedge all commodity price risk. We reclassify gains and losses on forward power contracts from AOCI into earnings in those periods in which the contracts settle. The following table provides information for DP&L concerning gains or losses recognized in AOCI for the cash flow hedges for the three months ended June 30, 2015 and 2014 : Three months ended Three months ended June 30, 2015 June 30, 2014 Interest Interest $ in millions (net of tax) Power Rate Hedge Power Rate Hedge Beginning accumulated derivative gain in AOCI $ 1.0 $ 2.4 $ (5.9 ) $ 4.9 Net gains / (losses) associated with current period hedging transactions 1.7 — (14.7 ) — Net gains / (losses) reclassified to earnings Interest expense — (0.2 ) — (0.3 ) Revenues (1.9 ) — 6.6 — Purchased power 0.3 — — — Ending accumulated derivative gain / (loss) in AOCI $ 1.1 $ 2.2 $ (14.0 ) $ 4.6 The following table provides information for DP&L concerning gains or losses recognized in AOCI for the cash flow hedges for the six months ended June 30, 2015 and 2014 : Six months ended Six months ended June 30, 2015 June 30, 2014 Interest Interest $ in millions (net of tax) Power Rate Hedge Power Rate Hedge Beginning accumulated derivative gain in AOCI $ 0.2 $ 2.6 $ 1.0 $ 5.2 Net gains / (losses) associated with current period hedging transactions 1.8 — (27.7 ) — Net gains / (losses) reclassified to earnings Interest expense — (0.4 ) — (0.6 ) Revenues (2.1 ) — 13.3 — Purchased power 1.2 — (0.6 ) — Ending accumulated derivative gain / (loss) in AOCI $ 1.1 $ 2.2 $ (14.0 ) $ 4.6 Portion expected to be reclassified to earnings in the next twelve months (a) $ 0.9 $ (0.7 ) Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months) 23 0 (a) The actual amounts that we reclassify from AOCI to earnings related to power can differ from the estimate above due to market price changes. Mark to Market Accounting Certain derivative contracts are entered into on a regular basis as part of our risk management program but do not qualify for hedge accounting or the normal purchases and sales exceptions under FASC 815. Accordingly, such contracts are recorded at fair value with changes in the fair value charged or credited to the Condensed Statements of Operations in the period in which the change occurred. This is commonly referred to as “MTM accounting.” Contracts we enter into as part of our risk management program may be settled financially, by physical delivery, or net settled with the counterparty. FTRs, natural gas forwards, heating oil futures and certain forward power contracts are marked to market. Certain qualifying derivative instruments have been designated as normal purchases or normal sales contracts, as provided under GAAP. Derivative contracts that have been designated as normal purchases or normal sales under GAAP are not subject to MTM accounting and are recognized in the Condensed Statements of Operations on an accrual basis. Regulatory Assets and Liabilities In accordance with regulatory accounting under GAAP, a cost or loss that is probable of recovery in future rates should be deferred as a regulatory asset and revenue or a gain that is probable of being returned to customers should be deferred as a regulatory liability. Portions of the derivative contracts that are marked to market each reporting period and are related to the retail portion of DP&L’s load requirements are included as part of the fuel and purchased power recovery rider approved by the PUCO which began January 1, 2010. Therefore, the Ohio retail customers’ portion of the heating oil futures is deferred as a regulatory asset or liability until the contracts settle. If these unrealized gains and losses are no longer deemed to be probable of recovery through our rates, they will be reclassified into earnings in the period such determination is made. The following tables present the amount and classification within the Condensed Statements of Operations or Condensed Balance Sheets of the gains and losses on DP&L’s derivatives not designated as hedging instruments for the three and six months ended June 30, 2015 and 2014 : For the three months ended June 30, 2015 $ in millions Heating Oil FTRs Power Total Change in unrealized gain / (loss) $ 0.1 $ (0.8 ) $ 1.1 $ 0.4 Realized loss (0.1 ) — (1.5 ) (1.6 ) Total $ — $ (0.8 ) $ (0.4 ) $ (1.2 ) Recorded in Income Statement: gain / (loss) Purchased power $ — $ (0.8 ) $ (2.9 ) $ (3.7 ) Revenues — — 2.5 2.5 Total $ — $ (0.8 ) $ (0.4 ) $ (1.2 ) For the three months ended June 30, 2014 $ in millions Heating Oil FTRs Power Total Change in unrealized loss $ 0.1 $ (1.2 ) $ 2.4 $ 1.3 Realized gain / (loss) — 0.6 0.6 1.2 Total $ 0.1 $ (0.6 ) $ 3.0 $ 2.5 Recorded in Income Statement: gain / (loss) Revenues $ — $ — $ 0.7 $ 0.7 Purchased power — (0.6 ) 2.3 1.7 Fuel 0.1 — — 0.1 Total $ 0.1 $ (0.6 ) $ 3.0 $ 2.5 For the six months ended June 30, 2015 $ in millions Heating Oil FTRs Power Natural Gas Total Change in unrealized gain / (loss) $ 0.2 $ 0.1 $ (1.8 ) $ 0.1 $ (1.4 ) Realized loss (0.1 ) (0.1 ) (3.8 ) (0.1 ) (4.1 ) Total $ 0.1 $ — $ (5.6 ) $ — $ (5.5 ) Recorded on Balance Sheet: gain / (loss) Regulatory Asset $ 0.1 $ — $ — $ — $ 0.1 Recorded in Income Statement: gain / (loss) Purchased power — — (7.8 ) — (7.8 ) Revenues — — 2.2 — 2.2 Total $ 0.1 $ — $ (5.6 ) $ — $ (5.5 ) For the six months ended June 30, 2014 $ in millions Heating Oil FTRs Power Total Change in unrealized loss $ (0.1 ) $ (1.5 ) $ (3.1 ) $ (4.7 ) Realized gain / (loss) 0.1 0.6 (0.8 ) (0.1 ) Total $ — $ (0.9 ) $ (3.9 ) $ (4.8 ) Recorded in Income Statement: gain / (loss) Revenues — — 1.4 $ 1.4 Purchased power — (0.9 ) (5.3 ) (6.2 ) Total $ — $ (0.9 ) $ (3.9 ) $ (4.8 ) DP&L has elected not to offset derivative assets and liabilities and not to offset net derivative positions against the right to reclaim cash collateral pledged (an asset) or the obligation to return cash collateral received (a liability) under derivative agreements. The following tables summarize the derivative positions presented in the balance sheet where a right of offset exists under these arrangements and related cash collateral received or pledged. The following table presents the fair value and balance sheet classification of DP&L’s derivative instruments at June 30, 2015 : Fair Values of Derivative Instruments at June 30, 2015 Gross Amounts Not Offset in the Condensed Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Balance Sheets Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Balance Fair Value Assets Short-term derivative positions (presented in Other current assets) Forward power contracts Cash Flow $ 6.8 $ (4.1 ) $ — $ 2.7 Forward power contracts MTM 4.4 (2.3 ) — 2.1 FTRs MTM 0.4 (0.4 ) — — Long-term derivative positions (presented in Other deferred assets) Forward power contracts Cash Flow 2.7 (1.4 ) — 1.3 Forward power contracts MTM 5.6 (1.4 ) — 4.2 Total assets $ 19.9 $ (9.6 ) $ — $ 10.3 Liabilities Short-term derivative positions (presented in Other current liabilities) Forward power contracts Cash Flow $ 5.3 $ (4.1 ) $ — $ 1.2 Forward power contracts MTM 9.7 (2.3 ) (7.3 ) 0.1 Heating oil futures MTM 0.1 — (0.1 ) — FTRs MTM 0.9 (0.4 ) — 0.5 Long-term derivative positions (presented in Other deferred liabilities) Forward power contracts Cash Flow 1.4 (1.4 ) — — Forward power contracts MTM 1.5 (1.4 ) — 0.1 Total liabilities $ 18.9 $ (9.6 ) $ (7.4 ) $ 1.9 The following table presents the fair value and balance sheet classification of DPL’s derivative instruments at December 31, 2014 : Fair Values of Derivative Instruments at December 31, 2014 Gross Amounts Not Offset in the Condensed Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Balance Sheets Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Balance Fair Value Assets Short-term derivative positions (presented in Other current assets) Forward power contracts Cash Flow $ 5.6 $ (2.0 ) $ — $ 3.6 Forward power contracts MTM 5.6 (3.4 ) — 2.2 Long-term derivative positions (presented in Other deferred assets) Forward power contracts Cash Flow 0.3 (0.3 ) — — Forward power contracts MTM 3.6 (0.9 ) — 2.7 Total assets $ 15.1 $ (6.6 ) $ — $ 8.5 Liabilities Short-term derivative positions (presented in Other current liabilities) Forward power contracts Cash Flow $ 2.1 $ (2.0 ) $ — $ 0.1 Forward power contracts MTM 7.5 (3.4 ) (4.1 ) — FTRs MTM 0.6 — — 0.6 Heating oil futures MTM 0.4 — (0.4 ) — Natural gas futures MTM 0.1 — (0.1 ) — Long-term derivative positions (presented in Other deferred liabilities) Forward power contracts Cash Flow 0.6 (0.3 ) (0.3 ) — Forward power contracts MTM 1.0 (0.9 ) — 0.1 Total liabilities $ 12.3 $ (6.6 ) $ (4.9 ) $ 0.8 The aggregate fair value of DP&L’s commodity derivative instruments that were in a MTM loss position at June 30, 2015 was $18.9 million . $7.4 million of collateral was posted directly with third parties and in a broker margin account which offsets our loss positions on the forward contracts. This liability position is further offset by the asset position of counterparties with master netting agreements of $9.6 million . Since our debt is below investment grade, we could be required to post collateral for the remaining $1.9 million .

Contractual Obligations, Commer

Contractual Obligations, Commercial Commitments and Contingencies	6 Months Ended
	Jun. 30, 2015
Contractual Obligations, Commercial Commitments and Contingencies	Contractual Obligations, Commercial Commitments and Contingencies DPL Inc. – Guarantees In the normal course of business, DPL enters into various agreements with its wholly owned subsidiaries, DPLE and DPLER, providing financial or performance assurance to third parties. These agreements are entered into primarily to support or enhance the creditworthiness otherwise attributed to these subsidiaries on a stand-alone basis, thereby facilitating the extension of sufficient credit to accomplish these subsidiaries’ intended commercial purposes. At June 30, 2015 , DPL had $19.3 million of guarantees to third parties for future financial or performance assurance under such agreements: $2.0 million of guarantees on behalf of DPLER and $17.3 million of guarantees on behalf of DPLE. The guarantee arrangements entered into by DPL with these third parties cover select present and future obligations of DPLE and DPLER to such beneficiaries and are terminable by DPL upon written notice to the beneficiaries within a certain time. The carrying amount of obligations for commercial transactions covered by these guarantees and recorded in our Condensed Consolidated Balance Sheets was $1.3 million at June 30, 2015 . To date, DPL has not incurred any losses related to the guarantees of DPLER’s or DPLE’s obligations and we believe it is remote that DPL would be required to perform or incur any losses in the future associated with any of the above guarantees. DP&L – Equity Ownership Interest DP&L owns a 4.9% equity ownership interest in OVEC, an electric generation company, which is recorded using the cost method of accounting under GAAP. As of June 30, 2015 , DP&L could be responsible for the repayment of 4.9% , or $74.4 million , of a $1,518.7 million debt obligation that has maturities from 2018 to 2040 . This would only happen if OVEC defaulted on its debt payments. As of June 30, 2015 , we have no knowledge of such a default. Commercial Commitments and Contractual Obligations There have been no material changes, outside the ordinary course of business, to our commercial commitments and to the information disclosed in the contractual obligations table in our Form 10-K for the fiscal year ended December 31, 2014 . Contingencies In the normal course of business, we are subject to various lawsuits, actions, proceedings, claims and other matters asserted under various laws and regulations. We believe the amounts provided in our Condensed Consolidated Financial Statements, as prescribed by GAAP, are adequate in light of the probable and estimable contingencies. However, there can be no assurances that the actual amounts required to satisfy alleged liabilities from various legal proceedings, claims, tax examinations and other matters discussed below, and to comply with applicable laws and regulations, will not exceed the amounts reflected in our Condensed Consolidated Financial Statements. As such, costs, if any, that may be incurred in excess of those amounts provided as of June 30, 2015 , cannot be reasonably determined. Environmental Matters DPL’s and DP&L’s facilities and operations are subject to a wide range of federal, state and local environmental regulations and laws. The environmental issues that may affect us include: • The federal CAA and state laws and regulations (including SIPs) which require compliance, obtaining permits and reporting as to air emissions, • Litigation with federal and certain state governments and certain special interest groups regarding whether modifications to or maintenance of certain coal-fired generating stations require additional permitting or pollution control technology, or whether emissions from coal-fired generating stations cause or contribute to climate change, • Rules and future rules issued by the USEPA and the Ohio EPA that require substantial reductions in SO2, particulates, mercury, acid gases, NOx, and other air emissions. DP&L has installed emission control technology and is taking other measures to comply with required and anticipated reductions, • Rules and future rules issued by the USEPA, the Ohio EPA or other authorities that require reporting and reductions of GHGs, • Rules and future rules issued by the USEPA associated with the federal Clean Water Act, which prohibits the discharge of pollutants into waters of the United States except pursuant to appropriate permits, and • Solid and hazardous waste laws and regulations, which govern the management and disposal of certain waste. The majority of solid waste created from the combustion of coal and fossil fuels is fly ash and other coal combustion by-products. In addition to imposing continuing compliance obligations, these laws and regulations authorize the imposition of substantial penalties for noncompliance, including fines, injunctive relief and other sanctions. In the normal course of business, we have investigatory and remedial activities underway at our facilities to comply, or to determine compliance, with such regulations. We record liabilities for loss contingencies related to environmental matters when a loss is probable of occurring and can be reasonably estimated in accordance with the provisions of GAAP. At June 30, 2015 , and December 31, 2014 , we had accruals of approximately $0.7 million and $0.8 million , respectively, for environmental matters and other claims. We also have a number of environmental matters for which we have not accrued loss contingencies because the risk of loss is not probable or a loss cannot be reasonably estimated, which are disclosed in the paragraphs below. We evaluate the potential liability related to environmental matters quarterly and may revise our accruals. Such revisions in the estimates of the potential liabilities could have a material adverse effect on our results of operations, financial condition or cash flows. We have several pending environmental matters associated with our EGUs and stations. Some of these matters could have material adverse effects on the operation of such EGUs and stations or our financial condition. Climate Change Legislation and Regulation On August 3, 2015, the EPA released the final CO 2 emissions rules for existing power plants, called the Clean Power Plan. The Clean Power Plan provides for interim emissions performance rates that must be achieved beginning in 2022 and final emissions performance rates by 2030. Legal challenges to the Clean Power Plan are expected. We are currently reviewing the rule and assessing the impact on our operations. Our business, financial condition or results of operations could be materially and adversely affected by this rule. Clean Water Act – Regulation of Water Discharge In December 2006, DP&L submitted a renewal application for the Stuart generating station NPDES permit that was due to expire on June 30, 2007. The Ohio EPA issued a draft permit that was received in November 2008. In September 2010, the USEPA formally objected to the November 2008, draft permit due to questions regarding the basis for the alternate thermal limitation. The Ohio EPA issued a draft permit in December 2011 and a public hearing was held in February 2012. The draft permit required DP&L, over the 54 months following issuance of a final permit, to take undefined actions to lower the temperature of its discharged water to a level unachievable by the station under its current design or alternatively make other significant modifications to the cooling water system. DP&L submitted comments to the draft permit. In November 2012, the Ohio EPA issued another draft which included a compliance schedule for performing a study to justify an alternate thermal limitation and to which DP&L submitted comments. In December 2012, the USEPA formally withdrew their objection to the permit. On January 7, 2013, the Ohio EPA issued a final permit. On February 1, 2013, DP&L appealed various aspects of the final permit to the Environmental Review Appeals Commission. A hearing before the Commission previously scheduled for August 2015 is in the process of being rescheduled. Depending on the outcome of the appeal process, the effects on DP&L’s operations could be material. Regulation of Waste Disposal In September 2002, DP&L and other parties received a special notice that the USEPA considers us to be a PRP for the clean-up of hazardous substances at the South Dayton Dump landfill site. In August 2005, DP&L and other parties received a general notice regarding the performance of a Remedial Investigation and Feasibility Study (RI/FS) under a Superfund Alternative Approach. In October 2005, DP&L received a special notice letter inviting it to enter into negotiations with the USEPA to conduct the RI/FS. No recent activity has occurred with respect to that notice or PRP status. On August 16, 2006, an Administrative Settlement Agreement and Order on Consent (“ASAOC”) for the site was executed and became effective among a group of PRPs, not including DP&L , and the USEPA. On August 25, 2009, the USEPA issued an Administrative Order requiring that access to DP&L’s service center building site, which is across the street from the landfill site, be given to the USEPA and the existing PRP group to help determine the extent of the landfill site’s contamination as well as to assess whether certain chemicals used at the service center building site might have migrated through groundwater to the landfill site. DP&L granted such access and drilling of soil borings and installation of monitoring wells occurred in late 2009 and early 2010. On May 24, 2010, three members of the existing PRP group, Hobart Corporation, Kelsey-Hayes Company and NCR Corporation, filed a civil complaint in the United States District Court for the Southern District of Ohio (the “District Court”) against DP&L and numerous other defendants alleging that DP&L and the other defendants contributed to the contamination at the landfill site and seeking reimbursement of the PRP group’s costs associated with the investigation and remediation of the site. On February 10, 2011, the District Court Judge dismissed claims against DP&L that related to allegations that chemicals used by DP&L at its service center contributed to the landfill site’s contamination. The District Court Judge, however, did not dismiss claims alleging financial responsibility for remediation costs based on hazardous substances from DP&L that were allegedly delivered by truck directly to the landfill. Discovery, including depositions of past and present DP&L employees, was conducted in 2012. On February 8, 2013, the District Court Judge granted DP&L’s motion for summary judgment on statute of limitations grounds with respect to claims seeking a contribution toward the costs that are expected to be incurred by the PRP group in performing an RI/FS under the August 15, 2006 ASAOC. That summary judgment ruling was appealed on March 4, 2013, and on July 14, 2014, a three-judge panel of the U.S. Court of Appeals for the 6 t h Circuit affirmed the lower Court’s ruling and subsequently denied a request by the PRP group for rehearing. On November 14, 2014, the PRP group appealed the decision to the U.S. Supreme Court, but the writ of certiorari was denied by the Court on January 20, 2015. On April 5, 2013, the PRP group entered into a second ASAOC (the "2013 ASAOC") relating primarily to vapor intrusion from under some of the buildings at the landfill site. On April 13, 2013, as amended July 30, 2013, the PRP group filed another civil complaint against DP&L and numerous other defendants alleging that each defendant contributed to the contamination of the site by delivering hazardous waste to the site or by releasing hazardous waste on other sites that migrated to the landfill site. On February 18, 2014, after considering various motions and alternative grounds to dismiss, the District Court Judge dismissed some of the alleged grounds for relief that the PRP group had made, but ruled in the PRP group’s favor with respect to motions to dismiss the case in its entirety finding, among other things, that the 2013 ASAOC involved a different scope of work and thus the contributions sought were not seeking the same remedy that had been dismissed in the first civil suit. Appeals of this ruling are pending before the 6t h Circuit Court of Appeals. On January 14, 2015, the PRP group served DP&L and other defendants a request for production of documents related to any waste management or waste disposal surveys. Information responsive to this request was provided on February 17, 2015. In addition, on January 16, 2015, the USEPA issued a Special Notice Letter and Section 104(e) Information Request to DP&L and other defendants, requesting historical information related to waste management practices that may be relevant to the site. DP&L responded to this request on March 27, 2015. In June 2015, DP&L was again requested to grant access to the DP&L service building property for the purpose of collecting groundwater samples from selected monitoring wells. DP&L granted access and groundwater sampling took place in June 2015. DP&L is unable to predict the outcome of these actions by the plaintiffs and USEPA. Additionally, the District Court’s 2013 ruling and the Court of Appeals’ affirmation of that ruling in 2014 does not address future litigation that may arise with respect to actual remediation costs. While DP&L is unable to predict the outcome of these and any future matters, if DP&L were required to contribute to the clean-up of the site, it could have a material adverse effect on its financial condition. Regulation of Ash Ponds There has been increasing advocacy to regulate coal combustion residuals (CCR). On June 21, 2010, the USEPA published a proposed rule seeking comments on two options under consideration for the regulation of coal combustion byproducts including regulating the material as a hazardous waste under RCRA Subtitle C or as a solid waste under RCRA Subtitle D. The USEPA released its final rule in December 2014, designating coal combustion residuals that are not beneficially reused as non-hazardous solid waste under RCRA Subtitle D. The rule was published in the Federal Register in April 2015 and becomes effective October 19, 2015, and applies new detailed management practices to new and existing landfills and surface impoundments, including lateral expansions of such units. Based on our review of the rule, we have adjusted our AROs related to ash ponds (see Note 8), but we are currently unable to determine the full impact of the rule as it is contingent upon future activities required by the regulation.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Contractual Obligations, Commercial Commitments and Contingencies	Contractual Obligations, Commercial Commitments and Contingencies DP&L – Equity Ownership Interest DP&L owns a 4.9% equity ownership interest in OVEC, an electric generation company, which is recorded using the cost method of accounting under GAAP. As of June 30, 2015 , DP&L could be responsible for the repayment of 4.9% , or $74.4 million , of a $1,518.7 million debt obligation that has maturities from 2018 to 2040 . This would only happen if OVEC defaulted on its debt payments. As of June 30, 2015 , we have no knowledge of such a default. Commercial Commitments and Contractual Obligations There have been no material changes, outside the ordinary course of business, to our commercial commitments and to the information disclosed in the contractual obligations table in our Form 10-K for the fiscal year ended December 31, 2014 . Contingencies In the normal course of business, we are subject to various lawsuits, actions, proceedings, claims and other matters asserted under laws and regulations. We believe the amounts provided in our Condensed Financial Statements, as prescribed by GAAP, are adequate in light of the probable and estimable contingencies. However, there can be no assurances that the actual amounts required to satisfy alleged liabilities from various legal proceedings, claims, tax examinations and other matters discussed below, and to comply with applicable laws and regulations, will not exceed the amounts reflected in our Condensed Financial Statements. As such, costs, if any, that may be incurred in excess of those amounts provided as of June 30, 2015 , cannot be reasonably determined. Environmental Matters DP&L’s facilities and operations are subject to a wide range of federal, state and local environmental regulations and laws. The environmental issues that may affect us include: • The federal CAA and state laws and regulations (including SIPs) which require compliance, obtaining permits and reporting as to air emissions, • Litigation with federal and certain state governments and certain special interest groups regarding whether modifications to or maintenance of certain coal-fired generating stations require additional permitting or pollution control technology, or whether emissions from coal-fired generating stations cause or contribute to climate change, • Rules and future rules issued by the USEPA and the Ohio EPA that require substantial reductions in SO2, particulates, mercury, acid gases, NOx, and other air emissions. DP&L has installed emission control technology and is taking other measures to comply with required and anticipated reductions, • Rules and future rules issued by the USEPA, the Ohio EPA or other authorities that require reporting and reductions of GHGs, • Rules and future rules issued by the USEPA associated with the federal Clean Water Act, which prohibits the discharge of pollutants into waters of the United States except pursuant to appropriate permits, and • Solid and hazardous waste laws and regulations, which govern the management and disposal of certain waste. The majority of solid waste created from the combustion of coal and fossil fuels is fly ash and other coal combustion by-products. In addition to imposing continuing compliance obligations, these laws and regulations authorize the imposition of substantial penalties for noncompliance, including fines, injunctive relief and other sanctions. In the normal course of business, we have investigatory and remedial activities underway at our facilities to comply, or to determine compliance, with such regulations. We record liabilities for loss contingencies related to environmental matters when a loss is probable of occurring and can be reasonably estimated in accordance with the provisions of GAAP. At June 30, 2015 , and December 31, 2014 , we had accruals of approximately $0.7 million and $0.8 million , respectively, for environmental matters and other claims. We also have a number of environmental matters for which we have not accrued loss contingencies because the risk of loss is not probable or a loss cannot be reasonably estimated, which are disclosed in the paragraphs below. We evaluate the potential liability related to environmental matters quarterly and may revise our estimates. Such revisions in the estimates of the potential liabilities could have a material adverse effect on our results of operations, financial condition or cash flows. We have several pending environmental matters associated with our EGUs and stations. Some of these matters could have material adverse effects on the operation of such EGUs and stations or our financial condition. Climate Change Legislation and Regulation On August 3, 2015, the EPA released the final CO 2 emissions rules for existing power plants, called the Clean Power Plan. The Clean Power Plan provides for interim emissions performance rates that must be achieved beginning in 2022 and final emissions performance rates by 2030. Legal challenges to the Clean Power Plan are expected. We are currently reviewing the rule and assessing the impact on our operations. Our business, financial condition or results of operations could be materially and adversely affected by this rule. Clean Water Act – Regulation of Water Discharge In December 2006, DP&L submitted a renewal application for the Stuart generating station NPDES permit that was due to expire on June 30, 2007. The Ohio EPA issued a draft permit that was received in November 2008. In September 2010, the USEPA formally objected to the November 2008, draft permit due to questions regarding the basis for the alternate thermal limitation. The Ohio EPA issued a draft permit in December 2011 and a public hearing was held in February 2012. The draft permit required DP&L, over the 54 months following issuance of a final permit, to take undefined actions to lower the temperature of its discharged water to a level unachievable by the station under its current design or alternatively make other significant modifications to the cooling water system. DP&L submitted comments to the draft permit. In November 2012, the Ohio EPA issued another draft which included a compliance schedule for performing a study to justify an alternate thermal limitation and to which DP&L submitted comments. In December 2012, the USEPA formally withdrew their objection to the permit. On January 7, 2013, the Ohio EPA issued a final permit. On February 1, 2013, DP&L appealed various aspects of the final permit to the Environmental Review Appeals Commission. A hearing before the Commission previously scheduled for August 2015 is in the process of being rescheduled. Depending on the outcome of the appeal process, the effects on DP&L’s operations could be material. Regulation of Waste Disposal In September 2002, DP&L and other parties received a special notice that the USEPA considers us to be a PRP for the clean-up of hazardous substances at the South Dayton Dump landfill site. In August 2005, DP&L and other parties received a general notice regarding the performance of a Remedial Investigation and Feasibility Study (RI/FS) under a Superfund Alternative Approach. In October 2005, DP&L received a special notice letter inviting it to enter into negotiations with the USEPA to conduct the RI/FS. No recent activity has occurred with respect to that notice or PRP status. On August 16, 2006, an Administrative Settlement Agreement and Order on Consent (“ASAOC”) for the site was executed and became effective among a group of PRPs, not including DP&L , and the USEPA. On August 25, 2009, the USEPA issued an Administrative Order requiring that access to DP&L’s service center building site, which is across the street from the landfill site, be given to the USEPA and the existing PRP group to help determine the extent of the landfill site’s contamination as well as to assess whether certain chemicals used at the service center building site might have migrated through groundwater to the landfill site. DP&L granted such access and drilling of soil borings and installation of monitoring wells occurred in late 2009 and early 2010. On May 24, 2010, three members of the existing PRP group, Hobart Corporation, Kelsey-Hayes Company and NCR Corporation, filed a civil complaint in the United States District Court for the Southern District of Ohio (the “District Court”) against DP&L and numerous other defendants alleging that DP&L and the other defendants contributed to the contamination at the landfill site and seeking reimbursement of the PRP group’s costs associated with the investigation and remediation of the site. On February 10, 2011, the District Court Judge dismissed claims against DP&L that related to allegations that chemicals used by DP&L at its service center contributed to the landfill site’s contamination. The District Court Judge, however, did not dismiss claims alleging financial responsibility for remediation costs based on hazardous substances from DP&L that were allegedly delivered by truck directly to the landfill. Discovery, including depositions of past and present DP&L employees, was conducted in 2012. On February 8, 2013, the District Court Judge granted DP&L’s motion for summary judgment on statute of limitations grounds with respect to claims seeking a contribution toward the costs that are expected to be incurred by the PRP group in performing an RI/FS under the August 15, 2006 ASAOC. That summary judgment ruling was appealed on March 4, 2013, and on July 14, 2014, a three-judge panel of the U.S. Court of Appeals for the 6 t h Circuit affirmed the lower Court’s ruling and subsequently denied a request by the PRP group for rehearing. On November 14, 2014, the PRP group appealed the decision to the U.S. Supreme Court, but the writ of certiorari was denied by the Court on January 20, 2015. On April 5, 2013, the PRP group entered into a second ASAOC (the "2013 ASAOC") relating primarily to vapor intrusion from under some of the buildings at the landfill site. On April 13, 2013, as amended July 30, 2013, the PRP group filed another civil complaint against DP&L and numerous other defendants alleging that each defendant contributed to the contamination of the site by delivering hazardous waste to the site or by releasing hazardous waste on other sites that migrated to the landfill site. On February 18, 2014, after considering various motions and alternative grounds to dismiss, the District Court Judge dismissed some of the alleged grounds for relief that the PRP group had made, but ruled in the PRP group’s favor with respect to motions to dismiss the case in its entirety finding, among other things, that the 2013 ASAOC involved a different scope of work and thus the contributions sought were not seeking the same remedy that had been dismissed in the first civil suit. Appeals of this ruling are pending before the 6t h Circuit Court of Appeals. On January 14, 2015, the PRP group served DP&L and other defendants a request for production of documents related to any waste management or waste disposal surveys. Information responsive to this request was provided on February 17, 2015. In addition, on January 16, 2015, the USEPA issued a Special Notice Letter and Section 104(e) Information Request to DP&L and other defendants, requesting historical information related to waste management practices that may be relevant to the site. DP&L responded to this request on March 27, 2015. In June 2015, DP&L was again requested to grant access to the DP&L service building property for the purpose of collecting groundwater samples from selected monitoring wells. DP&L granted access and groundwater sampling took place in June 2015. DP&L is unable to predict the outcome of these actions by the plaintiffs and USEPA. Additionally, the District Court’s 2013 ruling and the Court of Appeals’ affirmation of that ruling in 2014 does not address future litigation that may arise with respect to actual remediation costs. While DP&L is unable to predict the outcome of these and any future matters, if DP&L were required to contribute to the clean-up of the site, it could have a material adverse effect on its financial condition. Regulation of Ash Ponds There has been increasing advocacy to regulate coal combustion residuals (CCR). On June 21, 2010, the USEPA published a proposed rule seeking comments on two options under consideration for the regulation of coal combustion byproducts including regulating the material as a hazardous waste under RCRA Subtitle C or as a solid waste under RCRA Subtitle D. The USEPA released its final rule in December 2014, designating coal combustion residuals that are not beneficially reused as non-hazardous solid waste under RCRA Subtitle D. The rule was published in the Federal Register in April 2015 and becomes effective October 19, 2015, and applies new detailed management practices to new and existing landfills and surface impoundments, including lateral expansions of such units. Based on our review of the rule, we have adjusted our AROs related to ash ponds (see Note 8), but we are currently unable to determine the full impact of the rule as it is contingent upon future activities required by the regulation.

Business Segments

Business Segments	6 Months Ended
	Jun. 30, 2015
Segment Reporting [Abstract]
Business Segments	Business Segments DPL operates through two segments; Utility and Competitive Retail. The Utility segment consists of the operations of DPL’s subsidiary, DP&L . The Competitive Retail segment consists of DPL’s wholly owned subsidiary DPLER, which included, prior to its sale, DPLER’s wholly owned subsidiary, MC Squared. MC Squared was sold effective April 1, 2015. This is how we view our business and make decisions on how to allocate resources and evaluate performance. The Utility segment is comprised of DP&L’s electric generation, transmission and distribution businesses which generate and sell electricity to residential, commercial, industrial and governmental customers. DP&L generates electricity at five coal-fired power plants and DP&L distributes power to more than 516,000 retail customers who are located in a 6,000 square mile area of West Central Ohio. DP&L also sells electricity to DPLER and to other Ohio utilities and any excess energy and capacity is sold into the PJM wholesale market. DP&L’s transmission and distribution businesses are subject to rate regulation by federal and state regulators while rates for its generation business are deemed competitive under Ohio law. The Competitive Retail segment is comprised of the DPLER and, prior to its sale, MC Squared competitive retail electric service businesses which sell retail electric energy under contract to residential, commercial, industrial and governmental customers who have selected DPLER or MC Squared as their alternative electric supplier. As of June 30, 2015 , the Competitive Retail segment sold electricity to approximately 133,000 customers located throughout Ohio. On April 1, 2015, DPLER closed on the sale of MC Squared. The Competitive Retail segment’s electric energy used to meet its sales obligations was purchased from DP&L . The majority of intercompany sales from DP&L to DPLER are based on fixed-price contracts for each DPLER customer; the price approximates market prices for wholesale power at the inception of each customer’s contract. The Competitive Retail segment has no transmission or generation assets. The operations of the Competitive Retail segment are not subject to cost-of-service rate regulation by federal or state regulators. Included in the “Other” column in the following tables are other businesses that do not meet the GAAP requirements for disclosure as reportable segments as well as certain corporate costs including interest expense on DPL’s debt. Management evaluates segment performance based on gross margin. The accounting policies of the reportable segments are the same as those described in Note 1 – Overview and Summary of Significant Accounting Policies. Intersegment sales and profits are eliminated in consolidation. The following tables present financial information for each of DPL’s reportable business segments: $ in millions Utility Competitive Retail Other Adjustments and Eliminations DPL Consolidated For the three months ended June 30, 2015 Revenues from external customers $ 283.8 $ 75.2 $ 13.9 $ — $ 372.9 Intersegment revenues 68.3 — 1.3 (69.6 ) — Total revenues 352.1 75.2 15.2 (69.6 ) 372.9 Fuel 50.6 — 3.8 — 54.4 Purchased power 120.1 68.7 0.6 (68.8 ) 120.6 Gross margin $ 181.4 $ 6.5 $ 10.8 $ (0.8 ) $ 197.9 Depreciation and amortization $ 34.2 $ 0.1 $ — $ — $ 34.3 Interest expense 9.0 0.1 21.8 — 30.9 Income tax expense (benefit) 9.4 (5.5 ) (3.4 ) — 0.5 Net income / (loss) 23.9 6.7 (8.9 ) — 21.7 Cash capital expenditures $ 30.2 $ 0.1 $ 0.8 $ — $ 31.1 $ in millions Utility Competitive Retail Other Adjustments and Eliminations DPL Consolidated For the three months ended June 30, 2014 Revenues from external customers $ 254.0 $ 125.2 $ 11.0 $ (0.1 ) $ 390.1 Intersegment revenues 111.5 — 0.1 (111.6 ) — Total revenues 365.5 125.2 11.1 (111.7 ) 390.1 Fuel 58.6 — 2.2 — 60.8 Purchased power 136.9 111.1 1.3 (110.9 ) 138.4 Amortization of intangibles — — 0.3 — 0.3 Gross margin $ 170.0 $ 14.1 $ 7.3 $ (0.8 ) $ 190.6 Depreciation and amortization $ 35.3 $ 0.2 $ (1.5 ) $ (0.1 ) $ 33.9 Interest expense 8.3 0.1 23.6 (0.1 ) 31.9 Income tax expense (benefit) 6.0 1.3 (35.3 ) (0.1 ) (28.1 ) Net income / (loss) 13.9 2.6 17.3 — 33.8 Cash capital expenditures $ 25.6 $ — $ 1.2 $ — $ 26.8 $ in millions Utility Competitive Retail Other Adjustments and Eliminations DPL Consolidated For the six months ended June 30, 2015 Revenues from external customers $ 634.4 $ 197.5 $ 35.5 $ — $ 867.4 Intersegment revenues 179.0 — 2.9 (181.9 ) — Total revenues 813.4 197.5 38.4 (181.9 ) 867.4 Fuel 119.9 — 10.9 — 130.8 Purchased power 309.8 180.4 4.8 (180.2 ) 314.8 Gross margin $ 383.7 $ 17.1 $ 22.7 $ (1.7 ) $ 421.8 Depreciation and amortization $ 68.9 $ 0.4 $ — $ — $ 69.3 Interest expense 17.7 0.1 43.7 (0.1 ) 61.4 Income tax expense (benefit) 24.2 (4.2 ) (6.8 ) — 13.2 Net income / (loss) 60.4 8.3 (18.3 ) — 50.4 Cash capital expenditures $ 63.3 $ 0.3 $ 1.2 $ — $ 64.8 at June 30, 2015 Total assets $ 3,377.7 $ 49.8 $ 1,480.4 $ (1,283.4 ) $ 3,624.5 $ in millions Utility Competitive Retail Other Adjustments and Eliminations DPL Consolidated For the six months ended June 30, 2014 Revenues from external customers $ 546.6 $ 273.6 $ 30.2 $ — $ 850.4 Intersegment revenues 251.0 — 1.1 (252.1 ) — Total revenues 797.6 273.6 31.3 (252.1 ) 850.4 Fuel 142.9 — 7.9 — 150.8 Purchased power 304.9 251.3 6.7 (250.4 ) 312.5 Amortization of intangibles — — 0.6 — 0.6 Gross margin $ 349.8 $ 22.3 $ 16.1 $ (1.7 ) $ 386.5 Depreciation and amortization $ 71.8 $ 0.3 $ (2.9 ) $ — $ 69.2 Goodwill impairment — — 135.8 — 135.8 Fixed-asset impairment — — 11.5 — 11.5 Interest expense 16.1 0.2 46.7 (0.3 ) 62.7 Income tax expense (benefit) 10.0 0.6 60.1 — 70.7 Net income / (loss) 23.3 1.2 (239.7 ) — (215.2 ) Cash capital expenditures $ 53.0 $ — $ 2.2 $ — $ 55.2 at December 31, 2014 Total assets $ 3,338.7 $ 94.9 $ 1,440.1 $ (1,295.9 ) $ 3,577.8

Goodwill Impairment

Goodwill Impairment	6 Months Ended
	Jun. 30, 2015
Goodwill and Intangible Asset Impairment [Abstract]
Goodwill Impairment	Goodwill Impairment During the first quarter of 2014, we performed an interim impairment test on the $135.8 million in goodwill at our DPLER reporting unit. The DPLER reporting unit was identified as being "at risk" during the fourth quarter of 2013. The impairment indicators arose based on market information available regarding actual and proposed sales of competitive retail marketers, which indicated a significant decline in valuations during the first quarter of 2014. In Step 1 of the interim impairment test, the fair value of the reporting unit was determined to be less than its carrying amount under both the market approach and the income approach using a discounted cash flow valuation model. The significant assumptions included commodity price curves, estimated electricity to be demanded by its customers, changes in its customer base through attrition and expansion, discount rates, the assumed tax structure and the level of working capital required to run the business. During the second quarter of 2014, we finalized the work to determine the implied fair value for the DPLER reporting unit. There were no further adjustments to the full impairment of $135.8 million recognized in the first quarter.

Fixed Asset Impairment

Fixed Asset Impairment	6 Months Ended
	Jun. 30, 2015
Asset Impairment Charges [Abstract]
Fixed-asset Impairment	Fixed-asset Impairment During the first quarter of 2014, DP&L tested the recoverability of long-lived assets at East Bend, a 186 MW coal-fired plant in Kentucky jointly-owned by DP&L . Indications during that quarter that the fair value of the asset group was less than its carrying amount were determined to be impairment indicators given how narrowly these long-lived assets had passed the recoverability test during the fourth quarter of 2013. DP&L performed a long-lived asset impairment test and determined that the carrying amount of the asset group was not recoverable. The East Bend asset group was determined to have a fair value of $2.7 million using the market approach. As a result, we recognized an asset impairment expense of $11.5 million . In May 2014, an agreement was signed for the sale of DP&L’s interest in the generating assets at East Bend. The sale price approximated the carrying value. This transaction closed on December 30, 2014.

Shareholder's Equity

Shareholder's Equity	6 Months Ended
	Jun. 30, 2015
THE DAYTON POWER AND LIGHT COMPANY [Member]
Class of Stock [Line Items]
Shareholder's Equity	Shareholder’s Equity DP&L has 250,000,000 authorized $0.01 par value common shares, of which 41,172,173 are outstanding at June 30, 2015 . All common shares are held by DP&L’s parent, DPL . As part of the PUCO’s approval of the Merger, DP&L agreed to maintain a capital structure that includes an equity ratio of at least 50 percent and not to have a negative retained earnings balance.

Summary of Significant Accounti

Summary of Significant Accounting Policies (Policy)	6 Months Ended
	Jun. 30, 2015
Significant Accounting Policies [Line Items]
Description of Business	Description of Business DPL is a diversified regional energy company organized in 1985 under the laws of Ohio. DPL’s two reportable segments are the Utility segment, comprised of its DP&L subsidiary, and the Competitive Retail segment, comprised of its DPLER operations, which included the operations of DPLER’s wholly owned subsidiary MC Squared. MC Squared was sold effective April 1, 2015. See Note 11 for more information relating to these reportable segments. The terms “we,” “us,” “our” and “ours” are used to refer to DPL and its subsidiaries. DPL is an indirectly wholly owned subsidiary of AES. DP&L is a public utility incorporated in 1911 under the laws of Ohio. Beginning in 2001, Ohio law gave Ohio consumers the right to choose the electric generation supplier from whom they purchase retail generation service, however distribution and transmission retail services are still regulated. DP&L has the exclusive right to provide such distribution and transmission services to its more than 516,000 customers located in West Central Ohio. Additionally, DP&L offers retail SSO electric service to residential, commercial, industrial and governmental customers in a 6,000 square mile area of West Central Ohio and generates electricity at five coal-fired power stations. During 2015, DP&L is required to source 60% of the generation for its SSO customers through a competitive bid process and beginning January 2016, generation for its SSO customers will be 100% competitively bid. Principal industries located in DP&L’s service territory include automotive, food processing, paper, plastic, manufacturing and defense. DP&L's sales reflect the general economic conditions, seasonal weather patterns, retail competition in our service territory and the market price of electricity. DP&L sells any excess energy and capacity into the wholesale market. On June 4, 2014, the PUCO issued an entry on rehearing which requires DP&L to separate its generation assets from its transmission and distribution assets no later than January 1, 2017. While the OCC filed an application for rehearing on this Commission Order, it was denied by final order issued on July 23, 2014. DP&L also sells electricity to DPLER, an affiliate, to satisfy the electric requirements of DPLER’s retail customers. DPLER sells competitive retail electric service, under contract, to residential, commercial, industrial and governmental customers in Ohio. As of June 30, 2015 , DPLER has approximately 133,000 customers currently located throughout Ohio. On April 1, 2015, DPLER closed on the sale of its former subsidiary, MC Squared. DPLER does not own any transmission or generation assets, and all of DPLER’s electric energy was purchased from DP&L to meet its sales obligations. DPLER’s sales reflect the general economic conditions and seasonal weather patterns of the areas it serves. DPL’s other significant subsidiaries include DPLE, which owns and operates peaking generating facilities from which it makes wholesale sales of electricity, and MVIC, our captive insurance company that provides insurance services to our subsidiaries and us. DPL owns all of the common stock of its subsidiaries. DPL also has a wholly owned business trust, DPL Capital Trust II, formed for the purpose of issuing trust capital securities to investors. DP&L’s electric transmission and distribution businesses are subject to rate regulation by federal and state regulators while its generation business is deemed competitive under Ohio law. Accordingly, DP&L applies the accounting standards for regulated operations to its electric transmission and distribution businesses and records regulatory assets when incurred costs are expected to be recovered in future customer rates, and regulatory liabilities when current cost recoveries in customer rates relate to expected future costs. DPL and its subsidiaries employed 1,189 people as of June 30, 2015 , of which 1,151 were employed by DP&L . Approximately 61% of all DPL employees are under a collective bargaining agreement that expires on October 31, 2017.
Financial Statement Presentation	Financial Statement Presentation DPL’s Condensed Consolidated Financial Statements include the accounts of DPL and its wholly owned subsidiaries except for DPL Capital Trust II, which is not consolidated, consistent with the provisions of GAAP. DP&L has undivided ownership interests in five coal-fired generating facilities, various peaking generating facilities and numerous transmission facilities, all of which are included in the financial statements at amortized cost, which was adjusted to fair value at the date of the Merger for DPL . Operating revenues and expenses of these facilities are included on a pro rata basis in the corresponding lines in the Condensed Consolidated Statements of Operations. See Note 4 for more information. Certain immaterial amounts from prior periods have been reclassified to conform to the current period presentation. All material intercompany accounts and transactions are eliminated in consolidation. These financial statements have been prepared in accordance with GAAP for interim financial statements, the instructions of Form 10-Q and Regulation S-X. Accordingly, certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with GAAP have been omitted from this interim report. Therefore, our interim financial statements in this report should be read along with the annual financial statements included in our Form 10-K for the fiscal year ended December 31, 2014 . In the opinion of our management, the Condensed Consolidated Financial Statements presented in this report contain all adjustments necessary to fairly state our financial position as of June 30, 2015 ; our results of operations for the three and six months ended June 30, 2015 and 2014 and our cash flows for the six months ended June 30, 2015 and 2014 . Unless otherwise noted, all adjustments are normal and recurring in nature. Due to various factors, including, but not limited to, seasonal weather variations, the timing of outages of EGUs, changes in economic conditions involving commodity prices and competition, and other factors, interim results for the three and six months ended June 30, 2015 may not be indicative of our results that will be realized for the full year ending December 31, 2015 . The preparation of financial statements in conformity with GAAP requires us to make estimates and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the revenues and expenses of the periods reported. Actual results could differ from these estimates. Significant items subject to such estimates and judgments include: the carrying value of property, plant and equipment; unbilled revenues; the valuation of derivative instruments; the valuation of insurance and claims liabilities; the valuation of allowances for receivables and deferred income taxes; regulatory assets and liabilities; liabilities recorded for income tax exposures; litigation; contingencies; the valuation of AROs; assets and liabilities related to employee benefits; goodwill; and intangibles. As a result of push down accounting, DPL’s Condensed Consolidated Statements of Operations subsequent to the Merger include amortization expense relating to purchase accounting adjustments and depreciation of fixed assets based upon their fair value at the Merger date.
Sale of Receivables	Sale of Receivables DPLER and its former subsidiary MC Squared sell their customer receivables. These sales are at a small discount for cash at the billed amounts for their customers’ use of energy.
Accounting for Taxes Collected from Customers and Remitted to Governmental Authorities	Accounting for Taxes Collected from Customers and Remitted to Governmental Authorities DPL collects certain excise taxes levied by state or local governments from its customers. These taxes are accounted for on a net basis and not included in revenue.
Related Party Transactions	Related Party Transactions In December 2013, an agreement was signed, effective January 1, 2014, whereby the Service Company is to provide services including accounting, legal, human resources, information technology and other corporate services on behalf of companies that are part of the U.S. SBU, including, among other companies, DPL and DP&L . The Service Company allocates the costs for these services based on cost drivers designed to result in fair and equitable allocations. This includes ensuring that the regulated utilities served, including DP&L , are not subsidizing costs incurred for the benefit of non-regulated businesses. DPL charges the Service Company for employee payroll and benefit costs that are incurred on behalf of the Service Company.
Recently Issued Accounting Standards	Recently Issued Accounting Standards ASU No. 2015-03, Interest – Imputation of Interest (Subtopic 835-30) In April 2015, the FASB issued ASU No. 2015-03, which simplifies the presentation of debt issuance costs by requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this update. The standard is effective for annual reporting periods beginning after December 15, 2015 and interim periods therein, and requires the use of the full retrospective approach. Early adoption is permitted for financial statements that have not been previously issued. As of June 30, 2015 , DPL had approximately $19.0 million in deferred financing costs classified in other non-current assets that would be reclassified to reduce the related debt liabilities upon adoption of ASU No. 2015-03.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Significant Accounting Policies [Line Items]
Description of Business	Description of Business DP&L is a public utility incorporated in 1911 under the laws of Ohio. Beginning in 2001, Ohio law gave Ohio consumers the right to choose the electric generation supplier from whom they purchase retail generation service, however distribution and transmission retail services are still regulated. DP&L has the exclusive right to provide such distribution and transmission services to its more than 516,000 customers located in West Central Ohio. Additionally, DP&L offers retail SSO electric service to residential, commercial, industrial and governmental customers in a 6,000 square mile area of West Central Ohio. DP&L owns multiple coal-fired and peaking electric generating facilities as well as numerous transmission facilities, all of which are included in the financial statements at amortized cost. During 2015, DP&L is required to source 60% of the generation for its SSO customers through a competitive bid process, followed by 100% beginning in 2016. Principal industries located in DP&L’s service territory include automotive, food processing, paper, plastic, manufacturing and defense. DP&L's sales reflect the general economic conditions, seasonal weather patterns, retail competition in our service territory and the market price of electricity. DP&L sells any excess energy and capacity into the wholesale market. On June 4, 2014, the PUCO issued an entry on rehearing which requires DP&L to separate its generation assets from its transmission and distribution assets no later than January 1, 2017. While the OCC filed an application for rehearing on this Commission Order, it was denied by final order issued on July 23, 2014. DP&L also sells electricity to DPLER, an affiliate, to satisfy the electric requirements of DPLER’s retail customers. DP&L is a subsidiary of DPL . DP&L’s electric transmission and distribution businesses are subject to rate regulation by federal and state regulators while its generation business is deemed competitive under Ohio law. Accordingly, DP&L applies the accounting standards for regulated operations to its electric transmission and distribution businesses and records regulatory assets when incurred costs are expected to be recovered in future customer rates, and regulatory liabilities when current cost recoveries in customer rates relate to expected future costs. DP&L employed 1,151 people as of June 30, 2015 . Approximately 63% of all employees are under a collective bargaining agreement which expires on October 31, 2017.
Financial Statement Presentation	Financial Statement Presentation DP&L does not have any subsidiaries. DP&L has undivided ownership interests in five coal-fired generating facilities, peaking electric generating facilities and numerous transmission facilities, all of which are included in the financial statements at amortized cost. Operating revenues and expenses of these facilities are included on a pro rata basis in the corresponding lines in the Condensed Statements of Operations. See Note 4 for more information. Certain immaterial amounts from prior periods have been reclassified to conform to the current period presentation. These financial statements have been prepared in accordance with GAAP for interim financial statements, the instructions of Form 10-Q and Regulation S-X. Accordingly, certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with GAAP have been omitted from this interim report. Therefore, our interim financial statements in this report should be read along with the annual financial statements included in our Form 10-K for the fiscal year ended December 31, 2014 . In the opinion of our management, the Condensed Financial Statements presented in this report contain all adjustments necessary to fairly state our financial position as of June 30, 2015 ; our results of operations for the three and six months ended June 30, 2015 and 2014 and our cash flows for the six months ended June 30, 2015 and 2014. Unless otherwise noted, all adjustments are normal and recurring in nature. Due to various factors, including, but not limited to, seasonal weather variations, the timing of outages of EGUs, changes in economic conditions involving commodity prices and competition, and other factors, interim results for the six months ended June 30, 2015 may not be indicative of our results that will be realized for the full year ending December 31, 2015 . The preparation of financial statements in conformity with GAAP requires us to make estimates and judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities, and the revenues and expenses of the periods reported. Actual results could differ from these estimates. Significant items subject to such estimates and judgments include: the carrying value of property, plant and equipment; unbilled revenues; the valuation of derivative instruments; the valuation of insurance and claims liabilities; the valuation of allowances for receivables and deferred income taxes; regulatory assets and liabilities; liabilities recorded for income tax exposures; litigation; contingencies; the valuation of AROs; intangibles and assets and liabilities related to employee benefits.
Accounting for Taxes Collected from Customers and Remitted to Governmental Authorities	Accounting for Taxes Collected from Customers and Remitted to Governmental Authorities DP&L collects certain excise taxes levied by state or local governments from its customers. These taxes are accounted for on a net basis and not included in revenue. The amounts of such taxes collected for the three months ended June 30, 2015 and 2014 were $11.5 million and $11.6 million , respectively.
Recently Issued Accounting Standards	Recently Issued Accounting Standards ASU No. 2015-03, Interest – Imputation of Interest (Subtopic 835-30) In April 2015, the FASB issued ASU No. 2015-03, which simplifies the presentation of debt issuance costs by requiring that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by the amendments in this update. The standard is effective for annual reporting periods beginning after December 15, 2015 and interim periods therein, and requires the use of the full retrospective approach. Early adoption is permitted for financial statements that have not been previously issued. As of June 30, 2015 , DP&L had approximately $9.6 million in deferred financing costs classified in other non-current assets that would be reclassified to reduce the related debt liabilities upon adoption of ASU No. 2015-03. ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) In May 2014, the FASB issued ASU No. 2014-09 which clarifies principles for recognizing revenue and will result in a common revenue standard for GAAP and International Financial Reporting Standards. The objective of the new standard is to provide a single and comprehensive revenue recognition model for all contracts with customers to improve comparability, and it supersedes prior, industry-specific guidance. The revenue standard contains principles that an entity will apply to determine the measurement of revenue and timing of when revenue is recognized. The standard requires an entity to recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. In July 2015, the FASB decided to defer the effective date by one year, resulting in the new revenue standard being effective for annual reporting periods beginning after December 15, 2017 and interim periods therein. Early adoption is now permitted only as of the original effective date for public entities (that is, no earlier than 2017 for calendar year-end entities). The standard permits the use of two transition methods: either a full retrospective or modified retrospective approach. We have not yet selected a transition method and we are currently evaluating the impact of adopting the standard on our consolidated financial statements effective January 1, 2018. ASU No. 2015-11, Inventory: Simplifying the Measurement of Inventory (Topic 330) In July 2015, the FASB issued ASU No. 2015-11, which simplifies the subsequent measurement of inventory. It replaces the current lower of cost or market test with a lower of cost or net realizable value test. The standard is effective for public entities for annual reporting periods beginning after December 15, 2016, and interim periods therein. Early adoption is permitted. The new guidance must be applied prospectively. We are currently evaluating the impact of adopting the standard on our financial statements.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2015
Related Party Transaction [Line Items]
Schedule of Related Party Transactions	In the normal course of business, DPL enters into transactions with subsidiaries of AES. The following table provides a summary of these transactions: Three months ended Six months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Transactions with the Service Company Charges from the Service Company $ 9.8 $ 6.3 $ 19.6 $ 16.7 Charges to the Service Company $ 2.8 $ 0.6 $ 3.9 $ 1.1 at June 30, 2015 at December 31, 2014 Net prepaid / (payable) to the service company $ 4.0 $ (4.7 )
THE DAYTON POWER AND LIGHT COMPANY [Member]
Related Party Transaction [Line Items]
Schedule of Related Party Transactions	In the normal course of business, DP&L enters into transactions with other subsidiaries of DPL and AES . The following table provides a summary of these transactions: Three months ended Six months ended $ in millions 2015 2014 2015 2014 DP&L Revenues: Sales to DPLER (including MC Squared) (a) $ 68.3 $ 111.5 $ 179.0 $ 251.0 DP&L Operations and Maintenance Expenses: Premiums paid for insurance services provided by MVIC (b) $ (0.8 ) $ (0.7 ) $ (1.6 ) $ (1.4 ) Expense recoveries for services provided to DPLER (c) $ 0.6 $ 1.1 $ 1.3 $ 1.1 Transactions with the Service Company Charges from the Service Company $ 8.3 $ 6.4 $ 16.7 $ 16.8 Charges to the Service Company $ 2.8 $ 0.6 $ 3.9 $ 1.1 DP&L Customer security deposits: at June 30, 2015 at December 31, 2014 Deposits received from DPLER (d) $ 2.4 $ 20.1 Balances with the Service Company Net prepaid / (payable) to the service company $ 4.0 $ (4.7 ) (a) DP&L sells power to DPLER to satisfy the electric requirements of DPLER’s retail customers. The revenue dollars associated with sales to DPLER are recorded as wholesale revenues in DP&L’s Financial Statements. (b) MVIC, a wholly owned captive insurance subsidiary of DPL , provides insurance coverage to DP&L and other DPL subsidiaries for workers’ compensation, general liability, property damages and directors’ and officers’ liability. These amounts represent insurance premiums paid by DP&L to MVIC. DP&L received insurance proceeds from MVIC of $2.3 million and $0.4 million for the three months ended June 30, 2015 and 2014, respectively, and $3.8 million and $0.4 million for the six months ended June 30, 2015 and 2014, respectively. (c) In the normal course of business DP&L incurs and records expenses on behalf of DPLER. Such expenses include, but are not limited to, employee-related expenses, accounting, information technology, payroll, legal and other administrative expenses. DP&L subsequently charges these expenses to DPLER at DP&L’s cost and credits the expense in which they were initially recorded. (d) DP&L requires credit assurance from the CRES providers serving customers in its service territory because DP&L is the default energy provider should the CRES provider fail to fulfill its obligations to provide electricity. Due to DPL’s credit downgrade, DP&L required cash collateral from DPLER.

Supplemental Financial Inform24

Supplemental Financial Information (Tables)	6 Months Ended
	Jun. 30, 2015
Supplemental Financial Information [Line Items]
Schedule of Supplemental Financial Information	Accounts receivable and Inventories are as follows at June 30, 2015 and December 31, 2014 : June 30, December 31, $ in millions 2015 2014 Accounts receivable, net: Unbilled revenue $ 61.9 $ 79.2 Customer receivables 92.0 104.8 Amounts due from partners in jointly owned plants 20.0 14.2 Other 3.2 4.0 Provision for uncollectible accounts (1.4 ) (1.3 ) Total accounts receivable, net $ 175.7 $ 200.9 Inventories, at average cost: Fuel and limestone $ 67.8 $ 65.3 Plant materials and supplies 34.8 33.5 Other 2.1 1.4 Total inventories, at average cost $ 104.7 $ 100.2
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]	The amounts reclassified out of Accumulated Other Comprehensive Income / (Loss) by component during the six months ended June 30, 2015 and 2014 are as follows: Details about Accumulated Other Comprehensive Income / (Loss) components Affected line item in the Condensed Consolidated Statements of Operations Three months ended Six months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Gains and losses on Available-for-sale securities activity (Note 8): Other income $ 0.6 $ — $ — $ 0.3 Tax expense (0.2 ) — — (0.1 ) Net of income taxes 0.4 — — 0.2 Gains and losses on cash flow hedges (Note 9): Interest expense (0.3 ) (0.2 ) (0.5 ) (0.7 ) Revenue (2.9 ) 8.3 (3.2 ) 18.5 Purchased power 0.4 (0.1 ) 1.8 (1.2 ) Total before income taxes (2.8 ) 8.0 (1.9 ) 16.6 Tax expense 0.9 (2.7 ) 0.5 (5.8 ) Net of income taxes (1.9 ) 5.3 (1.4 ) 10.8 Amortization of defined benefit pension items (Note 7): Other income 0.1 — 0.2 — Tax expense (0.5 ) — (0.4 ) — Net of income taxes (0.4 ) — (0.2 ) — Total reclassifications for the period, net of income taxes $ (1.9 ) $ 5.3 $ (1.6 ) $ 11.0
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The changes in the components of Accumulated Other Comprehensive Income / (Loss) during the six months ended June 30, 2015 are as follows: $ in millions Gains / (losses) on available-for-sale securities Gains / (losses) on cash flow hedges Change in unfunded pension obligation Total Balance January 1, 2015 $ 0.5 $ 18.5 $ (11.5 ) $ 7.5 Other comprehensive income before reclassifications 0.1 1.8 — 1.9 Amounts reclassified from accumulated other comprehensive income / (loss) — (1.4 ) (0.2 ) (1.6 ) Net current period other comprehensive income / (loss) 0.1 0.4 (0.2 ) 0.3 Balance June 30, 2015 $ 0.6 $ 18.9 $ (11.7 ) $ 7.8
THE DAYTON POWER AND LIGHT COMPANY [Member]
Supplemental Financial Information [Line Items]
Schedule of Supplemental Financial Information	Accounts receivable and Inventories are as follows at June 30, 2015 and December 31, 2014 : June 30, December 31, $ in millions 2015 2014 Accounts receivable, net: Unbilled revenue $ 43.5 $ 49.0 Customer receivables 69.5 68.7 Amounts due from partners in jointly owned plants 20.0 14.2 Other 5.6 21.7 Provision for uncollectible accounts (1.0 ) (0.9 ) Total accounts receivable, net $ 137.6 $ 152.7 Inventories, at average cost: Fuel and limestone $ 67.8 $ 65.3 Plant materials and supplies 33.7 32.3 Other 2.0 1.4 Total inventories, at average cost $ 103.5 $ 99.0
Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]	The amounts reclassified out of Accumulated Other Comprehensive Income / (Loss) by component during the three and six months ended June 30, 2015 and 2014 are as follows: Details about Accumulated Other Comprehensive Income / (Loss) components Affected line item in the Condensed Statements of Operations Three months ended Six months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Gains and losses on Available-for-sale securities activity (Note 8): Other income $ 0.6 $ — $ — $ 0.3 Tax expense (0.2 ) — — (0.1 ) Net of income taxes 0.4 — — 0.2 Gains and losses on cash flow hedges (Note 9): Interest expense (0.3 ) (0.3 ) (0.6 ) (0.6 ) Revenue (2.9 ) 8.3 (3.2 ) 18.5 Purchased power 0.4 — 1.8 (1.0 ) Total before income taxes (2.8 ) 8.0 (2.0 ) 16.9 Tax expense 1.0 (1.6 ) 0.7 (4.8 ) Net of income taxes (1.8 ) 6.4 (1.3 ) 12.1 Amortization of defined benefit pension items (Note 7): Reclassification to Other income / (deductions) 1.4 1.1 2.8 2.1 Tax benefit (0.5 ) (0.3 ) (1.0 ) (0.7 ) Net of income taxes 0.9 0.8 1.8 1.4 Total reclassifications for the period, net of income taxes $ (0.5 ) $ 7.2 $ 0.5 $ 13.7
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The changes in the components of Accumulated Other Comprehensive Income / (Loss) during the six months ended June 30, 2015 are as follows: $ in millions Gains / (losses) on available-for-sale securities Gains / (losses) on cash flow hedges Change in unfunded pension obligation Total Balance January 1, 2015 $ 0.7 $ 2.8 $ (45.8 ) $ (42.3 ) Other comprehensive income before reclassifications — 1.8 — 1.8 Amounts reclassified from accumulated other comprehensive income / (loss) — (1.3 ) 1.8 0.5 Net current period other comprehensive income — 0.5 1.8 2.3 Balance June 30, 2015 $ 0.7 $ 3.3 $ (44.0 ) $ (40.0 )

Ownership of Coal-fired Facil25

Ownership of Coal-fired Facilities (Tables)	6 Months Ended
	Jun. 30, 2015
Jointly Owned Utility Plant Interests [Line Items]
Ownership Interests	DP&L’s undivided ownership interest in such facilities at June 30, 2015 is as follows: DP&L Share DPL Carrying value Jointly owned production units and stations: Ownership (%) Summer Production Capacity (MW) Gross Plant in Service ($ in millions) Accumulated Depreciation ($ in millions) Construction Work in Process ($ in millions) SCR and FGD Equipment Installed and in Service (Yes/No) Conesville Unit 4 16.5 129 $ 25 $ 3 $ 1 Yes Killen Station 67.0 402 339 25 1 Yes Miami Fort Units 7 and 8 36.0 368 218 28 4 Yes Stuart Station 35.0 808 234 19 11 Yes Zimmer Station 28.1 371 186 40 4 Yes Transmission (at varying percentages) n/a 42 7 — Total 2,078 $ 1,044 $ 122 $ 21
THE DAYTON POWER AND LIGHT COMPANY [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership Interests	DP&L’s undivided ownership interest in such facilities at June 30, 2015 , is as follows: DP&L Share DP&L Carrying value Jointly owned production units and stations: Ownership (%) Summer Production Capacity (MW) Gross Plant in Service ($ in millions) Accumulated Depreciation ($ in millions) Construction Work in Process ($ in millions) SCR and FGD Equipment Installed and in Service (Yes/No) Conesville Unit 4 16.5 129 $ 25 $ 6 $ 1 Yes Killen Station 67.0 402 654 321 1 Yes Miami Fort Units 7 and 8 36.0 368 366 167 4 Yes Stuart Station 35.0 808 771 331 11 Yes Zimmer Station 28.1 371 1,104 683 4 Yes Transmission (at varying percentages) n/a 98 63 — Total 2,078 $ 3,018 $ 1,571 $ 21

Debt Obligations (Tables)

Debt Obligations (Tables)	6 Months Ended
	Jun. 30, 2015
Debt Instrument [Line Items]
Long-term Debt	Long-term debt June 30, December 31, $ in millions 2015 2014 First mortgage bonds due in September 2016 - 1.875% $ 445.0 $ 445.0 Pollution control series due in January 2028 - 4.7% — 35.3 Pollution control series due in January 2034 - 4.8% 100.0 179.1 Pollution control series due in September 2036 - 4.8% 100.0 100.0 Pollution control series due in November 2040 - rates from: 0.02% - 0.12% and 0.04% - 0.15% (a) 100.0 100.0 U.S. Government note due in February 2061 - 4.2% 18.0 18.1 Unamortized debt discount / premiums, net (2.7 ) (2.8 ) Total long-term debt at subsidiary 760.3 874.7 Bank term loan due in May 2018 - rates from: 2.41% - 2.44% and 2.42% - 2.45% (a) 125.0 140.0 Senior unsecured bonds due in October 2016 - 6.5% 130.0 130.0 Senior unsecured bonds due in October 2019 - 6.75% 200.0 200.0 Senior unsecured bonds due in October 2021 - 7.25% 780.0 780.0 Note to DPL Capital Trust II due in September 2031 - 8.125% (b) 15.6 15.6 Unamortized debt discount / premiums, net (0.6 ) (0.7 ) Total non-current portion of long-term debt $ 2,010.3 $ 2,139.6
Current Portion - Long-term Debt	Current portion of long-term debt June 30, December 31, $ in millions 2015 2014 Pollution control series due in January 2028 - 4.7% $ 35.3 $ — Pollution control series due in January 2034 - 4.8% 79.1 — Bank term loan due in May 2018 - rates from: 2.41% - 2.44% and 2.42% - 2.45% (a) 35.0 20.0 U.S. Government note due in February 2061 - 4.2% 0.1 0.1 Total current portion of long-term debt $ 149.5 $ 20.1 (a) Range of interest rates for the six months ended June 30, 2015 and the twelve months ended December 31, 2014 , respectively. (b) Note payable to related party. See Note 1: Related Party Transactions for additional information.
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term Debt	Long-term debt June 30, December 31, $ in millions 2015 2014 First mortgage bonds due in September 2016 - 1.875% $ 445.0 $ 445.0 Pollution control series due in January 2028 - 4.7% — 35.3 Pollution control series due in January 2034 - 4.8% 100.0 179.1 Pollution control series due in September 2036 - 4.8% 100.0 100.0 Pollution control series due in November 2040 - rates from: 0.02% - 0.12% and 0.04% - 0.15% (a) 100.0 100.0 U.S. Government note due in February 2061 - 4.2% 18.0 18.1 Unamortized debt discount (0.3 ) (0.5 ) Total non-current portion of long-term debt $ 762.7 $ 877.0
Current Portion - Long-term Debt	Current portion of long-term debt June 30, December 31, $ in millions 2015 2014 Pollution control series due in January 2028 - 4.7% $ 35.3 $ — Pollution control series due in January 2034 - 4.8% 79.1 — U.S. Government note due in February 2061 - 4.2% 0.1 0.1 Total current portion of long-term debt $ 114.5 $ 0.1 (a) Range of interest rates for the six months ended June 30, 2015 and the twelve months ended December 31, 2014 , respectively.

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2015
Schedule of Effective Income Tax Rates	The following table details the effective tax rates for the three and six months ended June 30, 2015 and 2014 . Three months ended Six months ended June 30, June 30, 2015 2014 2015 2014 DPL 2.2% (4.8)% 20.7% (49.0)%
THE DAYTON POWER AND LIGHT COMPANY [Member]
Schedule of Effective Income Tax Rates	The following table details the effective tax rates for the three and six months ended June 30, 2015 and 2014 . Three months ended June 30, Six months ended June 30, 2015 2014 2015 2014 DP&L 27.9% 30.2% 28.5% 29.9%

Pension and Postretirement Be28

Pension and Postretirement Benefits (Tables)	6 Months Ended
	Jun. 30, 2015
Schedule of Net Periodic Benefit Cost / (Income)	The net periodic benefit cost of the pension and postretirement benefit plans for the three and six months ended June 30, 2015 and 2014 was: Net Periodic Benefit Cost Pension Postretirement Three months ended Three months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Service cost $ 1.8 $ 1.5 $ — $ — Interest cost 4.3 4.4 0.1 0.2 Expected return on plan assets (5.6 ) (5.6 ) — — Amortization of unrecognized: Prior service cost 0.5 0.3 — — Actuarial loss / (gain) 1.4 0.8 (0.1 ) (0.2 ) Net periodic benefit cost $ 2.4 $ 1.4 $ — $ — Net Periodic Benefit Cost Pension Postretirement Six months ended Six months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Service cost $ 3.6 $ 3.0 $ — $ 0.1 Interest cost 8.6 8.8 0.3 0.4 Expected return on plan assets (11.3 ) (11.4 ) — (0.1 ) Amortization of unrecognized: Prior service cost 1.0 0.7 — — Actuarial loss / (gain) 2.9 1.7 (0.2 ) (0.3 ) Net periodic benefit cost $ 4.8 $ 2.8 $ 0.1 $ 0.1
Estimated Future Benefit Payments and Medicare Part D Reimbursements	Benefit payments and Medicare Part D reimbursements, which reflect future service, are estimated to be paid as follows: $ in millions Pension Postretirement 2015 $ 12.4 $ 0.9 2016 25.2 1.8 2017 25.7 1.7 2018 26.3 1.6 2019 26.7 1.5 2020 - 2024 137.0 6.1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Net Periodic Benefit Cost / (Income)	The net periodic benefit cost of the pension and postretirement benefit plans for the three and six months ended June 30, 2015 and 2014 was: Net Periodic Benefit Cost Pension Postretirement Three months ended Three months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Service cost $ 1.7 $ 1.4 $ — $ 0.1 Interest cost 4.3 4.3 0.2 0.2 Expected return on plan assets (5.5 ) (5.6 ) — (0.1 ) Amortization of unrecognized: Prior service cost 0.8 0.7 — — Actuarial loss / (gain) 2.4 1.6 (0.1 ) (0.1 ) Net periodic benefit cost $ 3.7 $ 2.4 $ 0.1 $ 0.1 Net Periodic Benefit Cost Pension Postretirement Six months ended Six months ended June 30, June 30, $ in millions 2015 2014 2015 2014 Service cost $ 3.5 $ 2.9 $ — $ 0.1 Interest cost 8.6 8.7 0.4 0.4 Expected return on plan assets (11.2 ) (11.3 ) — (0.1 ) Amortization of unrecognized: Prior service cost 1.6 1.4 — — Actuarial loss / (gain) 4.8 3.2 (0.3 ) (0.3 ) Net periodic benefit cost $ 7.3 $ 4.9 $ 0.1 $ 0.1
Estimated Future Benefit Payments and Medicare Part D Reimbursements	Benefit payments and Medicare Part D reimbursements, which reflect future service, are estimated to be paid as follows: $ in millions Pension Postretirement 2015 $ 12.4 $ 0.9 2016 25.2 1.8 2017 25.7 1.7 2018 26.3 1.6 2019 26.7 1.5 2020 - 2024 137.0 6.1

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Cost Of Non-Derivative Instruments	The following table presents the fair value and cost of our non-derivative instruments at June 30, 2015 and December 31, 2014 . Information about the fair value of our derivative instruments can be found in Note 9. June 30, 2015 December 31, 2014 $ in millions Carrying Value Fair Value Carrying Value Fair Value Assets Money market funds $ 0.2 $ 0.2 $ 0.1 $ 0.1 Equity securities 2.7 3.7 2.7 3.7 Debt securities 4.5 4.5 4.7 4.7 Hedge funds 0.6 0.7 0.8 0.8 Real estate 0.3 0.3 0.4 0.4 Total Assets $ 8.3 $ 9.4 $ 8.7 $ 9.7 Liabilities Debt $ 2,159.8 $ 2,235.3 $ 2,159.7 $ 2,204.8
Fair Value of Assets and Liabilities Measured on Recurring Basis	The fair value of assets and liabilities at June 30, 2015 and December 31, 2014 and the respective category within the fair value hierarchy for DPL was determined as follows: Assets and Liabilities at Fair Value Level 1 Level 2 Level 3 $ in millions Fair value at June 30, 2015 Based on Quoted Prices in Active Markets Other Observable Inputs Unobservable Inputs Assets Master Trust assets Money market funds $ 0.2 $ 0.2 $ — $ — Equity securities 3.7 — 3.7 — Debt securities 4.5 — 4.5 — Hedge funds 0.7 — 0.7 — Real estate 0.3 — 0.3 — Total Master Trust assets 9.4 0.2 9.2 — Derivative Assets FTRs 0.4 — — 0.4 Forward power contracts 19.3 — 18.8 0.5 Total Derivative assets 19.7 — 18.8 0.9 Total Assets $ 29.1 $ 0.2 $ 28.0 $ 0.9 Liabilities Derivative Liabilities Heating oil 0.1 0.1 — — FTRs 0.9 — — 0.9 Forward power contracts 17.7 — 17.7 — Total Derivative liabilities 18.7 0.1 17.7 0.9 Debt 2,235.3 — 2,217.3 18.0 Total Liabilities $ 2,254.0 $ 0.1 $ 2,235.0 $ 18.9 Assets and Liabilities at Fair Value Level 1 Level 2 Level 3 $ in millions Fair value at December 31, 2014 Based on Quoted Prices in Active Markets Other Observable Inputs Unobservable Inputs Assets Master Trust assets Money market funds $ 0.1 $ 0.1 $ — $ — Equity securities 3.7 — 3.7 — Debt securities 4.7 — 4.7 — Hedge funds 0.8 — 0.8 — Real estate 0.4 — 0.4 — Total Master Trust assets 9.7 0.1 9.6 — Derivative assets Forward power contracts 14.9 — 13.7 1.2 Total Derivative assets 14.9 — 13.7 1.2 Total Assets $ 24.6 $ 0.1 $ 23.3 $ 1.2 Liabilities Derivative liabilities FTRs $ 0.6 $ — $ — 0.6 Heating oil futures 0.4 0.4 — — Natural gas futures 0.1 0.1 — — Forward power contracts 11.1 — 11.1 — Total Derivative liabilities 12.2 0.5 11.1 0.6 Debt 2,204.8 — 2,186.6 18.2 Total Liabilities $ 2,217.0 $ 0.5 $ 2,197.7 $ 18.8
Fair Value Measurements, Nonrecurring	The following table summarizes Goodwill and Long-lived assets measured at fair value on a non-recurring basis during the period and their level within the fair value hierarchy (there were no impairments during the six months ended June 30, 2015 ): $ in millions Six months ended June 30, 2014 Carrying Fair Value Gross Amount (c) Level 1 Level 2 Level 3 Loss Assets Long-lived assets (a) DP&L (East Bend) $ 14.2 $ — $ — $ 2.7 $ 11.5 Goodwill (b) DPLER Reporting unit $ 135.8 $ — $ — $ — $ 135.8 (a) See Note 13 for further information (b) See Note 12 for further information (c) Carrying amount at date of valuation
THE DAYTON POWER AND LIGHT COMPANY [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value and Cost Of Non-Derivative Instruments	The following table presents the fair value and cost of our non-derivative instruments at June 30, 2015 and December 31, 2014 . Information about the fair value of our derivative instruments can be found in Note 9. June 30, 2015 December 31, 2014 $ in millions Carrying Value Fair Value Carrying Value Fair Value Assets Money market funds $ 0.2 $ 0.2 $ 0.1 $ 0.1 Equity securities 2.7 3.7 2.7 3.7 Debt securities 4.5 4.5 4.7 4.7 Hedge funds 0.6 0.7 0.8 0.8 Real estate 0.3 0.3 0.4 0.4 Total assets $ 8.3 $ 9.4 $ 8.7 $ 9.7 Liabilities Debt $ 877.2 $ 883.1 $ 877.1 $ 882.5
Fair Value of Assets and Liabilities Measured on Recurring Basis	The fair value of assets and liabilities at June 30, 2015 and December 31, 2014 and the respective category within the fair value hierarchy for DP&L was determined as follows: Assets and Liabilities at Fair Value Level 1 Level 2 Level 3 $ in millions Fair value at June 30, 2015 Based on Quoted Prices in Active Markets Other Observable Inputs Unobservable Inputs Assets Master Trust assets Money market funds $ 0.2 $ 0.2 $ — $ — Equity securities 3.7 — 3.7 — Debt securities 4.5 — 4.5 — Hedge funds 0.7 — 0.7 — Real estate 0.3 — 0.3 — Total Master Trust assets 9.4 0.2 9.2 — Derivative assets FTRs 0.4 — — 0.4 Forward power contracts 19.5 — 19.0 0.5 Total derivative assets 19.9 — 19.0 0.9 Total assets $ 29.3 $ 0.2 $ 28.2 $ 0.9 Liabilities Derivative liabilities Heating oil $ 0.1 $ 0.1 $ — $ — FTRs 0.9 — — 0.9 Forward power contracts 17.9 — 17.9 — Total derivative liabilities 18.9 0.1 17.9 0.9 Debt 883.1 — 865.1 18.0 Total liabilities $ 902.0 $ 0.1 $ 883.0 $ 18.9 Assets and Liabilities at Fair Value Level 1 Level 2 Level 3 $ in millions Fair value at December 31, 2014 Based on Quoted Prices in Active Markets Other Observable Inputs Unobservable Inputs Assets Master Trust assets Money market funds $ 0.1 $ 0.1 $ — $ — Equity securities 3.7 — 3.7 — Debt securities 4.7 — 4.7 — Hedge funds 0.8 — 0.8 — Real estate 0.4 — 0.4 — Total Master Trust assets 9.7 0.1 9.6 — Derivative assets Forward power contracts 15.1 — 13.9 1.2 Total Derivative assets 15.1 — 13.9 1.2 Total assets $ 24.8 $ 0.1 $ 23.5 $ 1.2 Liabilities Derivative liabilities FTRs $ 0.6 $ — $ — $ 0.6 Heating oil futures 0.4 0.4 — — Natural gas futures 0.1 0.1 — — Forward power contracts 11.2 — 11.2 — Total Derivative liabilities 12.3 0.5 11.2 0.6 Debt 882.5 — 864.3 18.2 Total liabilities $ 894.8 $ 0.5 $ 875.5 $ 18.8

Derivative Instruments and He30

Derivative Instruments and Hedging Activities (Tables)	6 Months Ended
	Jun. 30, 2015
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Schedule of Notional Amounts of Outstanding Derivative Positions	At June 30, 2015 , DPL had the following outstanding derivative instruments: Commodity Accounting Treatment Unit Purchases (in thousands) Sales (in thousands) Net Purchases/ (Sales) (in thousands) FTRs Mark to Market MWh 24.2 — 24.2 Heating oil futures Mark to Market Gallons 168.0 — 168.0 Forward power contracts Cash Flow Hedge MWh 1,723.4 (8,809.4 ) (7,086.0 ) Forward power contracts Mark to Market MWh 3,621.9 (3,530.4 ) 91.5 At December 31, 2014 , DPL had the following outstanding derivative instruments: Commodity Accounting Treatment Unit Purchases (in thousands) Sales (in thousands) Net Purchases/ (Sales) (in thousands) FTRs Mark to Market MWh 10.5 — 10.5 Heating oil futures Mark to Market Gallons 378.0 — 378.0 Natural gas futures Mark to Market Dths 200.0 — 200.0 Forward power contracts Cash Flow Hedge MWh 175.0 (2,991.0 ) (2,816.0 ) Forward power contracts Mark to Market MWh 1,725.2 (2,707.8 ) (982.6 )
Gains or Losses Recognized in AOCI for the Cash Flow Hedges	The following table provides information for DPL concerning gains or losses recognized in AOCI for the cash flow hedges for the three months ended June 30, 2015 and 2014 : Three months ended Three months ended June 30, 2015 June 30, 2014 Interest Interest $ in millions (net of tax) Power Rate Hedge Power Rate Hedge Beginning accumulated derivative gain / (loss) in AOCI $ 1.0 $ 18.2 $ (5.7 ) $ 18.9 Net gains / (losses) associated with current period hedging transactions 1.7 — (12.1 ) — Net gains / (losses) reclassified to earnings Interest expense — (0.4 ) — (0.1 ) Revenues (1.9 ) — 5.5 — Purchased power 0.3 — (0.1 ) — Ending accumulated derivative gain / (loss) in AOCI $ 1.1 $ 17.8 $ (12.4 ) $ 18.8 The following table provides information for DPL concerning gains or losses recognized in AOCI for the cash flow hedges for the six months ended June 30, 2015 and 2014 : Six months ended Six months ended June 30, 2015 June 30, 2014 Interest Interest $ in millions (net of tax) Power Rate Hedge Power Rate Hedge Beginning accumulated derivative gain in AOCI $ 0.2 $ 18.3 $ 1.4 $ 19.2 Net gains / (losses) associated with current period hedging transactions 1.8 — (25.0 ) — Net gains / (losses) reclassified to earnings Interest expense — (0.5 ) — (0.4 ) Revenues (2.1 ) — 12.0 — Purchased power 1.2 — (0.8 ) — Ending accumulated derivative gain / (loss) in AOCI $ 1.1 $ 17.8 $ (12.4 ) $ 18.8 Portion expected to be reclassified to earnings in the next twelve months (a) $ 0.9 $ (0.6 ) Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months) 23 0 (a) The actual amounts that we reclassify from AOCI to earnings related to power can differ from the estimate above due to market price changes.
Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location	The following tables present the amount and classification within the Condensed Consolidated Statements of Operations or Condensed Consolidated Balance Sheets of the gains and losses on DPL’s derivatives not designated as hedging instruments for the three and six months ended June 30, 2015 and 2014 : For the three months ended June 30, 2015 $ in millions Heating Oil FTRs Power Total Change in unrealized gain / (loss) $ 0.1 $ (0.8 ) $ 1.2 $ 0.5 Realized loss (0.1 ) — (1.5 ) (1.6 ) Total $ — $ (0.8 ) $ (0.3 ) $ (1.1 ) Recorded in Income Statement: gain / (loss) Purchased power $ — $ (0.8 ) $ (2.8 ) $ (3.6 ) Revenue — — 2.5 2.5 Total $ — $ (0.8 ) $ (0.3 ) $ (1.1 ) For the three months ended June 30, 2014 $ in millions Heating Oil FTRs Power Total Change in unrealized loss $ 0.1 $ (1.2 ) $ 1.8 $ 0.7 Realized gain / (loss) — 0.6 0.5 1.1 Total $ 0.1 $ (0.6 ) $ 2.3 $ 1.8 Recorded in Income Statement: loss Purchased power $ — $ (0.6 ) $ 2.3 $ 1.7 Fuel 0.1 — — 0.1 Total $ 0.1 $ (0.6 ) $ 2.3 $ 1.8 For the six months ended June 30, 2015 $ in millions Heating Oil FTRs Power Natural Gas Total Change in unrealized gain / (loss) $ 0.2 $ 0.1 $ (1.7 ) $ 0.1 $ (1.3 ) Realized loss (0.1 ) (0.1 ) (3.8 ) (0.1 ) (4.1 ) Total $ 0.1 $ — $ (5.5 ) $ — $ (5.4 ) Recorded on Balance Sheet: gain/ (loss) Regulatory Asset $ 0.1 $ — $ — $ — $ 0.1 Recorded in Income Statement: gain / (loss) Purchased power — — (7.7 ) — (7.7 ) Revenue — — 2.2 — 2.2 Total $ 0.1 $ — $ (5.5 ) $ — $ (5.4 ) For the six months ended June 30, 2014 $ in millions Heating Oil FTRs Power Total Change in unrealized loss $ (0.1 ) $ (1.5 ) $ (3.7 ) $ (5.3 ) Realized gain / (loss) 0.1 0.6 (1.5 ) (0.8 ) Total $ — $ (0.9 ) $ (5.2 ) $ (6.1 ) Recorded in Income Statement: loss Purchased power $ — $ (0.9 ) $ (5.2 ) $ (6.1 ) Total $ — $ (0.9 ) $ (5.2 ) $ (6.1 )
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following tables summarize the derivative positions presented in the balance sheet where a right of offset exists under these arrangements and related cash collateral received or pledged. The following table presents the fair value and balance sheet classification of DPL’s derivative instruments at June 30, 2015 : Fair Values of Derivative Instruments at June 30, 2015 Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Consolidated Balance Sheets Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Balance Fair Value Assets Short-term derivative positions (presented in Other current assets) Forward power contracts Cash Flow $ 6.8 $ (4.1 ) $ — $ 2.7 Forward power contracts MTM 4.3 (2.3 ) — 2.0 FTRs MTM 0.4 (0.4 ) — — Long-term derivative positions (presented in Other deferred assets) Forward power contracts Cash Flow 2.7 (1.4 ) — 1.3 Forward power contracts MTM 5.5 (1.4 ) — 4.1 Total assets $ 19.7 $ (9.6 ) $ — $ 10.1 Liabilities Short-term derivative positions (presented in Other current liabilities) Forward power contracts Cash Flow $ 5.3 $ (4.1 ) $ — $ 1.2 Forward power contracts MTM 9.6 (2.3 ) (7.3 ) — Heating oil MTM 0.1 — (0.1 ) — FTRs MTM 0.9 (0.4 ) — 0.5 Long-term derivative positions (presented in Other deferred liabilities) Forward power contracts Cash Flow 1.4 (1.4 ) — — Forward power contracts MTM 1.4 (1.4 ) — — Total liabilities $ 18.7 $ (9.6 ) $ (7.4 ) $ 1.7 The following table presents the fair value and balance sheet classification of DPL’s derivative instruments at December 31, 2014 : Fair Values of Derivative Instruments at December 31, 2014 Gross Amounts Not Offset in the Condensed Consolidated Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Consolidated Balance Sheets Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Balance Fair Value Assets Short-term derivative positions (presented in Other current assets) Forward power contracts Cash Flow $ 5.6 $ (2.0 ) $ — $ 3.6 Forward power contracts MTM 5.5 (3.4 ) — 2.1 Long-term derivative positions (presented in Other deferred assets) Forward power contracts Cash Flow 0.3 (0.3 ) — — Forward power contracts MTM 3.5 (0.9 ) — 2.6 Total assets $ 14.9 $ (6.6 ) $ — $ 8.3 Liabilities Short-term derivative positions (presented in Other current liabilities) Forward power contracts Cash Flow $ 2.1 $ (2.0 ) $ — $ 0.1 Forward power contracts MTM 7.5 (3.4 ) (4.1 ) — FTRs MTM 0.6 — — 0.6 Heating oil futures MTM 0.4 — (0.4 ) — Natural gas MTM 0.1 — (0.1 ) — Long-term derivative positions (presented in Other deferred liabilities) Forward power contracts Cash Flow 0.6 (0.3 ) (0.3 ) — Forward power contracts MTM 0.9 (0.9 ) — — Total liabilities $ 12.2 $ (6.6 ) $ (4.9 ) $ 0.7
THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Schedule of Notional Amounts of Outstanding Derivative Positions	At June 30, 2015 , DP&L had the following outstanding derivative instruments: Commodity Accounting Treatment Unit Purchases (in thousands) Sales (in thousands) Net Purchases/ (Sales) (in thousands) FTRs Mark to Market MWh 24.2 — 24.2 Heating oil futures Mark to Market Gallons 168.0 — 168.0 Forward power contracts Cash Flow Hedge MWh 1,723.4 (8,809.4 ) (7,086.0 ) Forward power contracts Mark to Market MWh 3,621.9 (3,606.8 ) 15.1 At December 31, 2014 , DP&L had the following outstanding derivative instruments: Commodity Accounting Treatment Unit Purchases (in thousands) Sales (in thousands) Net Purchases/ (Sales) (in thousands) FTRs Mark to Market MWh 10.5 — 10.5 Heating oil futures Mark to Market Gallons 378.0 — 378.0 Natural Gas Mark to Market Dths 200.0 — 200.0 Forward power contracts Cash Flow Hedge MWh 175.0 (2,991.0 ) (2,816.0 ) Forward power contracts Mark to Market MWh 1,725.2 (2,804.0 ) (1,078.8 )
Gains or Losses Recognized in AOCI for the Cash Flow Hedges	The following table provides information for DP&L concerning gains or losses recognized in AOCI for the cash flow hedges for the three months ended June 30, 2015 and 2014 : Three months ended Three months ended June 30, 2015 June 30, 2014 Interest Interest $ in millions (net of tax) Power Rate Hedge Power Rate Hedge Beginning accumulated derivative gain in AOCI $ 1.0 $ 2.4 $ (5.9 ) $ 4.9 Net gains / (losses) associated with current period hedging transactions 1.7 — (14.7 ) — Net gains / (losses) reclassified to earnings Interest expense — (0.2 ) — (0.3 ) Revenues (1.9 ) — 6.6 — Purchased power 0.3 — — — Ending accumulated derivative gain / (loss) in AOCI $ 1.1 $ 2.2 $ (14.0 ) $ 4.6 The following table provides information for DP&L concerning gains or losses recognized in AOCI for the cash flow hedges for the six months ended June 30, 2015 and 2014 : Six months ended Six months ended June 30, 2015 June 30, 2014 Interest Interest $ in millions (net of tax) Power Rate Hedge Power Rate Hedge Beginning accumulated derivative gain in AOCI $ 0.2 $ 2.6 $ 1.0 $ 5.2 Net gains / (losses) associated with current period hedging transactions 1.8 — (27.7 ) — Net gains / (losses) reclassified to earnings Interest expense — (0.4 ) — (0.6 ) Revenues (2.1 ) — 13.3 — Purchased power 1.2 — (0.6 ) — Ending accumulated derivative gain / (loss) in AOCI $ 1.1 $ 2.2 $ (14.0 ) $ 4.6 Portion expected to be reclassified to earnings in the next twelve months (a) $ 0.9 $ (0.7 ) Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months) 23 0 (a) The actual amounts that we reclassify from AOCI to earnings related to power can differ from the estimate above due to market price changes.
Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location	The following tables present the amount and classification within the Condensed Statements of Operations or Condensed Balance Sheets of the gains and losses on DP&L’s derivatives not designated as hedging instruments for the three and six months ended June 30, 2015 and 2014 : For the three months ended June 30, 2015 $ in millions Heating Oil FTRs Power Total Change in unrealized gain / (loss) $ 0.1 $ (0.8 ) $ 1.1 $ 0.4 Realized loss (0.1 ) — (1.5 ) (1.6 ) Total $ — $ (0.8 ) $ (0.4 ) $ (1.2 ) Recorded in Income Statement: gain / (loss) Purchased power $ — $ (0.8 ) $ (2.9 ) $ (3.7 ) Revenues — — 2.5 2.5 Total $ — $ (0.8 ) $ (0.4 ) $ (1.2 ) For the three months ended June 30, 2014 $ in millions Heating Oil FTRs Power Total Change in unrealized loss $ 0.1 $ (1.2 ) $ 2.4 $ 1.3 Realized gain / (loss) — 0.6 0.6 1.2 Total $ 0.1 $ (0.6 ) $ 3.0 $ 2.5 Recorded in Income Statement: gain / (loss) Revenues $ — $ — $ 0.7 $ 0.7 Purchased power — (0.6 ) 2.3 1.7 Fuel 0.1 — — 0.1 Total $ 0.1 $ (0.6 ) $ 3.0 $ 2.5 For the six months ended June 30, 2015 $ in millions Heating Oil FTRs Power Natural Gas Total Change in unrealized gain / (loss) $ 0.2 $ 0.1 $ (1.8 ) $ 0.1 $ (1.4 ) Realized loss (0.1 ) (0.1 ) (3.8 ) (0.1 ) (4.1 ) Total $ 0.1 $ — $ (5.6 ) $ — $ (5.5 ) Recorded on Balance Sheet: gain / (loss) Regulatory Asset $ 0.1 $ — $ — $ — $ 0.1 Recorded in Income Statement: gain / (loss) Purchased power — — (7.8 ) — (7.8 ) Revenues — — 2.2 — 2.2 Total $ 0.1 $ — $ (5.6 ) $ — $ (5.5 ) For the six months ended June 30, 2014 $ in millions Heating Oil FTRs Power Total Change in unrealized loss $ (0.1 ) $ (1.5 ) $ (3.1 ) $ (4.7 ) Realized gain / (loss) 0.1 0.6 (0.8 ) (0.1 ) Total $ — $ (0.9 ) $ (3.9 ) $ (4.8 ) Recorded in Income Statement: gain / (loss) Revenues — — 1.4 $ 1.4 Purchased power — (0.9 ) (5.3 ) (6.2 ) Total $ — $ (0.9 ) $ (3.9 ) $ (4.8 )
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value	The following table presents the fair value and balance sheet classification of DP&L’s derivative instruments at June 30, 2015 : Fair Values of Derivative Instruments at June 30, 2015 Gross Amounts Not Offset in the Condensed Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Balance Sheets Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Balance Fair Value Assets Short-term derivative positions (presented in Other current assets) Forward power contracts Cash Flow $ 6.8 $ (4.1 ) $ — $ 2.7 Forward power contracts MTM 4.4 (2.3 ) — 2.1 FTRs MTM 0.4 (0.4 ) — — Long-term derivative positions (presented in Other deferred assets) Forward power contracts Cash Flow 2.7 (1.4 ) — 1.3 Forward power contracts MTM 5.6 (1.4 ) — 4.2 Total assets $ 19.9 $ (9.6 ) $ — $ 10.3 Liabilities Short-term derivative positions (presented in Other current liabilities) Forward power contracts Cash Flow $ 5.3 $ (4.1 ) $ — $ 1.2 Forward power contracts MTM 9.7 (2.3 ) (7.3 ) 0.1 Heating oil futures MTM 0.1 — (0.1 ) — FTRs MTM 0.9 (0.4 ) — 0.5 Long-term derivative positions (presented in Other deferred liabilities) Forward power contracts Cash Flow 1.4 (1.4 ) — — Forward power contracts MTM 1.5 (1.4 ) — 0.1 Total liabilities $ 18.9 $ (9.6 ) $ (7.4 ) $ 1.9 The following table presents the fair value and balance sheet classification of DPL’s derivative instruments at December 31, 2014 : Fair Values of Derivative Instruments at December 31, 2014 Gross Amounts Not Offset in the Condensed Balance Sheets $ in millions Hedging Designation Gross Fair Value as presented in the Condensed Balance Sheets Financial Instruments with Same Counterparty in Offsetting Position Cash Collateral Net Balance Fair Value Assets Short-term derivative positions (presented in Other current assets) Forward power contracts Cash Flow $ 5.6 $ (2.0 ) $ — $ 3.6 Forward power contracts MTM 5.6 (3.4 ) — 2.2 Long-term derivative positions (presented in Other deferred assets) Forward power contracts Cash Flow 0.3 (0.3 ) — — Forward power contracts MTM 3.6 (0.9 ) — 2.7 Total assets $ 15.1 $ (6.6 ) $ — $ 8.5 Liabilities Short-term derivative positions (presented in Other current liabilities) Forward power contracts Cash Flow $ 2.1 $ (2.0 ) $ — $ 0.1 Forward power contracts MTM 7.5 (3.4 ) (4.1 ) — FTRs MTM 0.6 — — 0.6 Heating oil futures MTM 0.4 — (0.4 ) — Natural gas futures MTM 0.1 — (0.1 ) — Long-term derivative positions (presented in Other deferred liabilities) Forward power contracts Cash Flow 0.6 (0.3 ) (0.3 ) — Forward power contracts MTM 1.0 (0.9 ) — 0.1 Total liabilities $ 12.3 $ (6.6 ) $ (4.9 ) $ 0.8

Business Segments (Tables)

Business Segments (Tables)	6 Months Ended
	Jun. 30, 2015
Segment Reporting [Abstract]
Financial Reporting for Reportable Business Segments	The following tables present financial information for each of DPL’s reportable business segments: $ in millions Utility Competitive Retail Other Adjustments and Eliminations DPL Consolidated For the three months ended June 30, 2015 Revenues from external customers $ 283.8 $ 75.2 $ 13.9 $ — $ 372.9 Intersegment revenues 68.3 — 1.3 (69.6 ) — Total revenues 352.1 75.2 15.2 (69.6 ) 372.9 Fuel 50.6 — 3.8 — 54.4 Purchased power 120.1 68.7 0.6 (68.8 ) 120.6 Gross margin $ 181.4 $ 6.5 $ 10.8 $ (0.8 ) $ 197.9 Depreciation and amortization $ 34.2 $ 0.1 $ — $ — $ 34.3 Interest expense 9.0 0.1 21.8 — 30.9 Income tax expense (benefit) 9.4 (5.5 ) (3.4 ) — 0.5 Net income / (loss) 23.9 6.7 (8.9 ) — 21.7 Cash capital expenditures $ 30.2 $ 0.1 $ 0.8 $ — $ 31.1 $ in millions Utility Competitive Retail Other Adjustments and Eliminations DPL Consolidated For the three months ended June 30, 2014 Revenues from external customers $ 254.0 $ 125.2 $ 11.0 $ (0.1 ) $ 390.1 Intersegment revenues 111.5 — 0.1 (111.6 ) — Total revenues 365.5 125.2 11.1 (111.7 ) 390.1 Fuel 58.6 — 2.2 — 60.8 Purchased power 136.9 111.1 1.3 (110.9 ) 138.4 Amortization of intangibles — — 0.3 — 0.3 Gross margin $ 170.0 $ 14.1 $ 7.3 $ (0.8 ) $ 190.6 Depreciation and amortization $ 35.3 $ 0.2 $ (1.5 ) $ (0.1 ) $ 33.9 Interest expense 8.3 0.1 23.6 (0.1 ) 31.9 Income tax expense (benefit) 6.0 1.3 (35.3 ) (0.1 ) (28.1 ) Net income / (loss) 13.9 2.6 17.3 — 33.8 Cash capital expenditures $ 25.6 $ — $ 1.2 $ — $ 26.8 $ in millions Utility Competitive Retail Other Adjustments and Eliminations DPL Consolidated For the six months ended June 30, 2015 Revenues from external customers $ 634.4 $ 197.5 $ 35.5 $ — $ 867.4 Intersegment revenues 179.0 — 2.9 (181.9 ) — Total revenues 813.4 197.5 38.4 (181.9 ) 867.4 Fuel 119.9 — 10.9 — 130.8 Purchased power 309.8 180.4 4.8 (180.2 ) 314.8 Gross margin $ 383.7 $ 17.1 $ 22.7 $ (1.7 ) $ 421.8 Depreciation and amortization $ 68.9 $ 0.4 $ — $ — $ 69.3 Interest expense 17.7 0.1 43.7 (0.1 ) 61.4 Income tax expense (benefit) 24.2 (4.2 ) (6.8 ) — 13.2 Net income / (loss) 60.4 8.3 (18.3 ) — 50.4 Cash capital expenditures $ 63.3 $ 0.3 $ 1.2 $ — $ 64.8 at June 30, 2015 Total assets $ 3,377.7 $ 49.8 $ 1,480.4 $ (1,283.4 ) $ 3,624.5 $ in millions Utility Competitive Retail Other Adjustments and Eliminations DPL Consolidated For the six months ended June 30, 2014 Revenues from external customers $ 546.6 $ 273.6 $ 30.2 $ — $ 850.4 Intersegment revenues 251.0 — 1.1 (252.1 ) — Total revenues 797.6 273.6 31.3 (252.1 ) 850.4 Fuel 142.9 — 7.9 — 150.8 Purchased power 304.9 251.3 6.7 (250.4 ) 312.5 Amortization of intangibles — — 0.6 — 0.6 Gross margin $ 349.8 $ 22.3 $ 16.1 $ (1.7 ) $ 386.5 Depreciation and amortization $ 71.8 $ 0.3 $ (2.9 ) $ — $ 69.2 Goodwill impairment — — 135.8 — 135.8 Fixed-asset impairment — — 11.5 — 11.5 Interest expense 16.1 0.2 46.7 (0.3 ) 62.7 Income tax expense (benefit) 10.0 0.6 60.1 — 70.7 Net income / (loss) 23.3 1.2 (239.7 ) — (215.2 ) Cash capital expenditures $ 53.0 $ — $ 2.2 $ — $ 55.2 at December 31, 2014 Total assets $ 3,338.7 $ 94.9 $ 1,440.1 $ (1,295.9 ) $ 3,577.8

Summary of Significant Accoun32

Summary of Significant Accounting Policies (Narrative) (Details) mi² in Thousands, customer in Thousands	1 Months Ended	6 Months Ended
	Jan. 31, 2016	Jun. 30, 2015mi²employeecustomergenerating_facilitysegment
Significant Accounting Policies [Line Items]
Number of reportable segments | segment		2
Approximate number of competitive retail customers		133
Entity number of employees | employee		1,189
Employees under a collective bargaining agreement which expires in October-2011		61.00%
THE DAYTON POWER AND LIGHT COMPANY [Member]
Significant Accounting Policies [Line Items]
Approximate number of retail customers		516
Service area, square miles | mi²		6
Number of generating facilities | generating_facility		5
Entity number of employees | employee		1,151
Employees under a collective bargaining agreement which expires in October-2011		63.00%
Year 2015 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Significant Accounting Policies [Line Items]
Electric generation through competitive bid		60.00%
Year 2016 [Member] | Scenario, Forecast [Member]
Significant Accounting Policies [Line Items]
Electric generation through competitive bid	100.00%

Summary of Significant Accoun33

Summary of Significant Accounting Policies (Related Party Transactions) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Sales to related party	$ 2.8	$ 0.6	$ 3.9	$ 1.1
Charges for services provided	9.8	6.3	19.6	16.7
Net prepaid/(payable) to the service company	4		4		$ (4.7)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Sales to related party	2.8	0.6	3.9	1.1
Premiums paid for insurance services provided by MVIC	(0.8)	(0.7)	(1.6)	(1.4)
Expense recoveries for services provided to DPLER	0.6	1.1	1.3	1.1
Charges for services provided	8.3	6.4	16.7	16.8
Deposits received from DPLER	2.4		2.4		20.1
Net prepaid/(payable) to the service company	4		4		$ (4.7)
DPLER [Member]
Sales to related party	68.3	111.5	179	251
MVIC [Member] | Insurance Proceeds Received [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Insurance proceeds received	$ 2.3	$ 0.4	$ 3.8	$ 0.4

Summary of Significant Accoun34

Summary of Significant Accounting Policies (Sale of Receivables) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accounting Policies [Abstract]
Proceeds from sale of other receivables	$ 6.6	$ 28.9	$ 39.7	$ 61

Summary of Signficant Accountin

Summary of Signficant Accounting Policies (Accounting for Taxes Collected from Customers and Remitted to Governmental Authorities) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Significant Accounting Policies [Line Items]
Excise taxes collected	$ 11.5	$ 11.6	$ 25.5	$ 25.9
THE DAYTON POWER AND LIGHT COMPANY [Member]
Significant Accounting Policies [Line Items]
Excise taxes collected	$ 11.5	$ 11.6	$ 25.5	$ 25.9

Summary of Significant Accoun36

Summary of Significant Accounting Policies (Recently Issued Accounting Standards) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2015USD ($)
Significant Accounting Policies [Line Items]
Deferred financing costs to be reclassed and deducted from debt amount	$ 19
THE DAYTON POWER AND LIGHT COMPANY [Member]
Significant Accounting Policies [Line Items]
Deferred financing costs to be reclassed and deducted from debt amount	$ 9.6

Supplemental Financial Inform37

Supplemental Financial Information (Supplemental Financial Information) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Supplemental Financial Information [Line Items]
Unbilled revenue	$ 61.9	$ 79.2
Customer receivables	92	104.8
Amounts due from partners in jointly owned stations	20	14.2
Other	3.2	4
Provision for uncollectible accounts	(1.4)	(1.3)
Total accounts receivable, net	175.7	200.9
Fuel and Limestone	67.8	65.3
Plant materials and supplies	34.8	33.5
Other	2.1	1.4
Total inventories, at average cost	104.7	100.2
THE DAYTON POWER AND LIGHT COMPANY [Member]
Supplemental Financial Information [Line Items]
Unbilled revenue	43.5	49
Customer receivables	69.5	68.7
Amounts due from partners in jointly owned stations	20	14.2
Other	5.6	21.7
Provision for uncollectible accounts	(1)	(0.9)
Total accounts receivable, net	137.6	152.7
Fuel and Limestone	67.8	65.3
Plant materials and supplies	33.7	32.3
Other	2	1.4
Total inventories, at average cost	$ 103.5	$ 99

Supplemental Financial Inform38

Supplemental Financial Information (Reclassification out of ACOI) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income	$ (30.9)	$ (33.8)	$ (62.1)	$ (63.3)
Tax expense	(0.5)	28.1	(13.2)	(70.7)
Net income / (loss)	21.7	33.8	50.4	(215.2)
Interest expense	(30.9)	(31.9)	(61.4)	(62.7)
Revenue	372.9	390.1	867.4	850.4
Purchased power	(120.6)	(138.4)	(314.8)	(312.5)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income	(8.8)	(8.6)	(17.8)	(16.4)
Tax expense	(9.4)	(6)	(24.2)	(10)
Net income / (loss)	23.9	13.9	60.4	23.3
Interest expense	(9)	(8.3)	(17.7)	(16.1)
Revenue	352.1	365.5	813.4	797.6
Purchased power	(120.1)	(136.9)	(309.8)	(304.9)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net income / (loss)	(1.9)	5.3	(1.6)	11
Reclassification out of Accumulated Other Comprehensive Income [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net income / (loss)	(0.5)	7.2	0.5	13.7
Gains / (losses) on available-for-sale securities [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income	0.6	0	0	0.3
Tax expense	(0.2)	0	0	(0.1)
Net income / (loss)	0.4	0	0	0.2
Gains / (losses) on available-for-sale securities [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income	0.6	0	0	0.3
Tax expense	(0.2)	0	0	(0.1)
Net income / (loss)	0.4	0	0	0.2
Gains / (losses) on cash flow hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Tax expense	0.9	(2.7)	0.5	(5.8)
Net income / (loss)	(1.9)	5.3	(1.4)	10.8
Interest expense	(0.3)	(0.2)	(0.5)	(0.7)
Revenue	(2.9)	8.3	(3.2)	18.5
Purchased power	0.4	(0.1)	1.8	(1.2)
Total before income taxes	(2.8)	8	(1.9)	16.6
Gains / (losses) on cash flow hedges [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Tax expense	1	(1.6)	0.7	(4.8)
Net income / (loss)	(1.8)	6.4	(1.3)	12.1
Interest expense	(0.3)	(0.3)	(0.6)	(0.6)
Revenue	(2.9)	8.3	(3.2)	18.5
Purchased power	0.4	0	1.8	(1)
Total before income taxes	(2.8)	8	(2)	16.9
Amortization of defined benefit pension items [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income	0.1	0	0.2	0
Tax expense	(0.5)	0	(0.4)	0
Net income / (loss)	(0.4)	0	(0.2)	0
Amortization of defined benefit pension items [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other income	1.4	1.1	2.8	2.1
Tax expense	(0.5)	(0.3)	(1)	(0.7)
Net income / (loss)	$ 0.9	$ 0.8	$ 1.8	$ 1.4

Supplemental Financial Inform39

Supplemental Financial Information (Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			$ 7.5
Other comprehensive income before reclassifications			1.9
Amounts reclassified from accumulated other comprehensive income / (loss)			(1.6)
Other comprehensive income / (loss)	$ (0.6)	$ (6.7)	0.3	$ (14.2)
Balance, end of period	7.8		7.8
THE DAYTON POWER AND LIGHT COMPANY [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(42.3)
Other comprehensive income before reclassifications			1.8
Amounts reclassified from accumulated other comprehensive income / (loss)			0.5
Other comprehensive income / (loss)	0.7	$ (7.5)	2.3	$ (14.2)
Balance, end of period	(40)		(40)
Gains / (losses) on available-for-sale securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			0.5
Other comprehensive income before reclassifications			0.1
Amounts reclassified from accumulated other comprehensive income / (loss)			0
Other comprehensive income / (loss)			0.1
Balance, end of period	0.6		0.6
Gains / (losses) on available-for-sale securities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			0.7
Other comprehensive income before reclassifications			0
Amounts reclassified from accumulated other comprehensive income / (loss)			0
Other comprehensive income / (loss)			0
Balance, end of period	0.7		0.7
Gains / (losses) on cash flow hedges [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			18.5
Other comprehensive income before reclassifications			1.8
Amounts reclassified from accumulated other comprehensive income / (loss)			(1.4)
Other comprehensive income / (loss)			0.4
Balance, end of period	18.9		18.9
Gains / (losses) on cash flow hedges [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			2.8
Other comprehensive income before reclassifications			1.8
Amounts reclassified from accumulated other comprehensive income / (loss)			(1.3)
Other comprehensive income / (loss)			0.5
Balance, end of period	3.3		3.3
Change in unfunded pension obligation [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(11.5)
Other comprehensive income before reclassifications			0
Amounts reclassified from accumulated other comprehensive income / (loss)			(0.2)
Other comprehensive income / (loss)			(0.2)
Balance, end of period	(11.7)		(11.7)
Change in unfunded pension obligation [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period			(45.8)
Other comprehensive income before reclassifications			0
Amounts reclassified from accumulated other comprehensive income / (loss)			1.8
Other comprehensive income / (loss)			1.8
Balance, end of period	$ (44)		$ (44)

Regulatory Assets and Liabili40

Regulatory Assets and Liabilities (Details) $ in Millions	6 Months Ended
	Jun. 30, 2015USD ($)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Regulatory Assets [Line Items]
Recovery of deferred storm costs	$ 11.1

Ownership of Coal-fired Facil41

Ownership of Coal-fired Facilities (Narrative) (Details)	6 Months Ended
	Jun. 30, 2015generating_facility
THE DAYTON POWER AND LIGHT COMPANY [Member]
Jointly Owned Utility Plant Interests [Line Items]
Number of generating facilities	5

Ownership of Coal-fired Facil42

Ownership of Coal-fired Facilities (Ownership Interests) (Details) - Jun. 30, 2015 $ in Millions	USD ($)MW
THE DAYTON POWER AND LIGHT COMPANY [Member] | Total Jointly-owned Stations [Member]
Construction Work in Process	$ 21
DP&L Share [Member] | Conesville Unit 4 [Member]
Ownership (%)	16.50%
Production Capacity (MW) | MW	129
DP&L Share [Member] | Killen Station [Member]
Ownership (%)	67.00%
Production Capacity (MW) | MW	402
DP&L Share [Member] | Miami Fort Units 7 and 8 [Member]
Ownership (%)	36.00%
Production Capacity (MW) | MW	368
DP&L Share [Member] | Stuart Station [Member]
Ownership (%)	35.00%
Production Capacity (MW) | MW	808
DP&L Share [Member] | Zimmer Station [Member]
Ownership (%)	28.10%
Production Capacity (MW) | MW	371
DP&L Share [Member] | Total Jointly-owned Stations [Member]
Production Capacity (MW) | MW	2,078
DP&L Share [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Conesville Unit 4 [Member]
Ownership (%)	16.50%
Production Capacity (MW) | MW	129
DP&L Share [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Killen Station [Member]
Ownership (%)	67.00%
Production Capacity (MW) | MW	402
DP&L Share [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Miami Fort Units 7 and 8 [Member]
Ownership (%)	36.00%
Production Capacity (MW) | MW	368
DP&L Share [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Stuart Station [Member]
Ownership (%)	35.00%
Production Capacity (MW) | MW	808
DP&L Share [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Zimmer Station [Member]
Ownership (%)	28.10%
Production Capacity (MW) | MW	371
DP&L Share [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Total Jointly-owned Stations [Member]
Production Capacity (MW) | MW	2,078
DP&L Investment [Member] | Conesville Unit 4 [Member]
Gross Plant In Service	$ 25
Accumulated Depreciation	3
Construction Work in Process	$ 1
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Killen Station [Member]
Gross Plant In Service	$ 339
Accumulated Depreciation	25
Construction Work in Process	$ 1
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Miami Fort Units 7 and 8 [Member]
Gross Plant In Service	$ 218
Accumulated Depreciation	28
Construction Work in Process	$ 4
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Stuart Station [Member]
Gross Plant In Service	$ 234
Accumulated Depreciation	19
Construction Work in Process	$ 11
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Zimmer Station [Member]
Gross Plant In Service	$ 186
Accumulated Depreciation	40
Construction Work in Process	$ 4
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | Transmission (At Varying Percentages) [Member]
Gross Plant In Service	$ 42
Accumulated Depreciation	7
DP&L Investment [Member] | Total Jointly-owned Stations [Member]
Gross Plant In Service	1,044
Accumulated Depreciation	122
Construction Work in Process	21
DP&L Investment [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Conesville Unit 4 [Member]
Gross Plant In Service	25
Accumulated Depreciation	6
Construction Work in Process	$ 1
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Killen Station [Member]
Gross Plant In Service	$ 654
Accumulated Depreciation	321
Construction Work in Process	$ 1
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Miami Fort Units 7 and 8 [Member]
Gross Plant In Service	$ 366
Accumulated Depreciation	167
Construction Work in Process	$ 4
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Stuart Station [Member]
Gross Plant In Service	$ 771
Accumulated Depreciation	331
Construction Work in Process	$ 11
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Zimmer Station [Member]
Gross Plant In Service	$ 1,104
Accumulated Depreciation	683
Construction Work in Process	$ 4
SCR and FGD Equipment Installed and In Service	Yes
DP&L Investment [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Transmission (At Varying Percentages) [Member]
Gross Plant In Service	$ 98
Accumulated Depreciation	63
DP&L Investment [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Total Jointly-owned Stations [Member]
Gross Plant In Service	3,018
Accumulated Depreciation	$ 1,571

Debt Obligations (Narrative) (D

Debt Obligations (Narrative) (Details)	Aug. 03, 2015USD ($)	Jul. 31, 2015USD ($)	Jul. 01, 2015USD ($)	Jun. 30, 2015USD ($)letter_of_creditdebt_covenantfiscal_quarter	Dec. 31, 2014USD ($)
Debt Instrument [Line Items]
Current portion - long-term debt				$ 149,500,000	$ 20,100,000
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Current portion - long-term debt				114,500,000	100,000
Revolving Credit Agreeement with Bank Group Expiring 2018 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Unsecured revolving credit agreement				$ 300,000,000
Unsecured revolving credit agreement, term				5 years
Letter of credit sublimit				$ 100,000,000
Line of credit facility, additional borrowing capacity				$ 100,000,000
Number of letters of credit outstanding | letter_of_credit				2
Letters of credit outstanding				$ 1,400,000
Line of credit facility, remaining borrowing capacity				$ 298,600,000
Revolving Credit Agreement and Standby Letters of Credit [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Number of financial covenants | debt_covenant				2
Number of prior quarters included in EBITDA to interest calculation | fiscal_quarter				4
Pollution Control Series Maturing in January 2028 - 4.70% [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage				4.70%
Current portion - long-term debt				$ 35,300,000	0
Term loan outstanding					35,300,000
Pollution Control Series Maturing in January 2028 - 4.70% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Current portion - long-term debt				35,300,000	0
Term loan outstanding				$ 0	35,300,000
Pollution Control Series Maturing in January 2028 - 4.70% [Member] | Subsequent Event [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt called/redeemed			$ 35,300,000
Debt instrument interest percentage			4.70%
Pollution Control Series Maturing in January 2034 - 4.80% [Member]
Debt Instrument [Line Items]
Debt instrument interest percentage				4.80%
Current portion - long-term debt				$ 79,100,000	0
Term loan outstanding				100,000,000	179,100,000
Pollution Control Series Maturing in January 2034 - 4.80% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Current portion - long-term debt				79,100,000	0
Term loan outstanding				100,000,000	179,100,000
Pollution Control Series Maturing in January 2034 - 4.80% [Member] | Subsequent Event [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt called/redeemed	$ 137,800,000		$ 41,300,000
Debt instrument interest percentage	4.80%		4.80%
Repayments of debt	$ 37,800,000
Pollution Control Series Maturing in January 2034 - 4.80% [Member] | July 1, 2015 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Current portion - long-term debt				41,300,000
Pollution Control Series Maturing in January 2034 - 4.80% [Member] | August 3, 2015 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Current portion - long-term debt				37,800,000
Variable Rate Notes Backed by Term Loan and First Mortgage Bonds [Member] | Subsequent Event [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Variable rate notes issued	200,000,000
Pollution Control Bonds [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Current portion - long-term debt				114,400,000
Pollution control series maturing in November 2040 [Member]
Debt Instrument [Line Items]
Term loan outstanding				100,000,000	100,000,000
Pollution control series maturing in November 2040 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Term loan outstanding				100,000,000	100,000,000
Pollution control series maturing in November 2040 [Member] | Subsequent Event [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Debt called/redeemed	$ 100,000,000
Bank term loan due in May 2018 - rates from: 2.41% - 2.44% and 2.42% - 2.45% [Member]
Debt Instrument [Line Items]
Current portion - long-term debt				35,000,000	20,000,000
Term loan outstanding				125,000,000	$ 140,000,000
Bank term loan due in May 2018 - rates from: 2.41% - 2.44% and 2.42% - 2.45% [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt called/redeemed		$ 35,000,000
Term loan outstanding		160,000,000
Bank Term Loan Maturing July 2020 [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Term loan outstanding		125,000,000
Revolving Credit Agreement with Bank Group Expiring 2020 [Member] | Subsequent Event [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Unsecured revolving credit agreement		175,000,000
Letter of credit sublimit		50,000,000
Line of credit facility, additional borrowing capacity		100,000,000
DPL Revolving Credit Facility [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Unsecured revolving credit agreement				$ 100,000,000
Unsecured revolving credit agreement, term				5 years
Letter of credit sublimit				$ 100,000,000
Line of credit facility, additional borrowing capacity				$ 50,000,000
Number of letters of credit outstanding | letter_of_credit				1
Letters of credit outstanding				$ 2,300,000
Line of credit facility, remaining borrowing capacity				$ 97,700,000
DPL Revolving Credit Facility [Member] | Revolving Credit Facility [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Unsecured revolving credit agreement		205,000,000
Letter of credit sublimit		200,000,000
Line of credit facility, additional borrowing capacity		$ 95,000,000
Revolving Credit Agreement and Term Loan [Member]
Debt Instrument [Line Items]
Number of financial covenants | debt_covenant				2
Number of prior quarters included in EBITDA to interest calculation | fiscal_quarter				4
Number of prior quarters included in debt to EBITDA ratio | fiscal_quarter				4

Debt Obligations (Long-term Deb

Debt Obligations (Long-term Debt) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Unamortized debt discount / premiums, net	$ (0.6)	$ (0.7)
Total long-term debt at subsidary	760.3	874.7
Total long-term debt	2,010.3	2,139.6
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Unamortized debt discount / premiums, net	(2.7)	(2.8)
Unamortized debt discount	(0.3)	(0.5)
Total long-term debt	762.7	877
First Mortgage Bonds Maturing in September 2016 - 1.875% [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 445	445
Debt instrument maturity year	Sep. 1, 2016
Debt instrument interest percentage	1.875%
First Mortgage Bonds Maturing in September 2016 - 1.875% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 445	445
Pollution Control Series Maturing in January 2028 - 4.70% [Member]
Debt Instrument [Line Items]
Long-term debt, gross		35.3
Debt instrument maturity year	Jan. 1, 2028
Debt instrument interest percentage	4.70%
Pollution Control Series Maturing in January 2028 - 4.70% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 0	35.3
Pollution Control Series Maturing in January 2034 - 4.80% [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 100	179.1
Debt instrument maturity year	Jan. 1, 2034
Debt instrument interest percentage	4.80%
Pollution Control Series Maturing in January 2034 - 4.80% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 100	179.1
Pollution Control Series Maturing in September 2036 - 4.80% [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 100	100
Debt instrument maturity year	Sep. 1, 2036
Debt instrument interest percentage	4.80%
Pollution Control Series Maturing in September 2036 - 4.80% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 100	100
Pollution control series maturing in November 2040 - rates: 0.02% - 0.12% and 0.04% - 0.15% [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 100	$ 100
Debt instrument maturity year	Nov. 1, 2040
Debt instrument interest percentage minimum	0.02%	0.04%
Debt instrument interest percentage maximum	0.12%	0.15%
Pollution control series maturing in November 2040 - rates: 0.02% - 0.12% and 0.04% - 0.15% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 100	$ 100
U.S. Government note maturing in February 2061 - 4.20% [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 18	18.1
Debt instrument maturity year	Feb. 1, 2061
Debt instrument interest percentage	4.20%
Debt instrument interest percentage minimum
U.S. Government note maturing in February 2061 - 4.20% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 18	18.1
Bank term loan due in May 2018 - rates from: 2.41% - 2.44% and 2.42% - 2.45% [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 125	$ 140
Debt instrument maturity year	May 1, 2018
Debt instrument interest percentage minimum	2.41%	2.42%
Debt instrument interest percentage maximum	2.44%	2.45%
Senior unsecured due in October 2016 - 6.5% [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 130	$ 130
Debt instrument maturity year	Oct. 1, 2016
Debt instrument interest percentage	6.50%
Senior unsecured due in October 2019 - 6.75% [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 200	200
Debt instrument maturity year	Oct. 1, 2019
Debt instrument interest percentage	6.75%
Senior unsecured due in October 2021 - 7.25% [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 780	780
Debt instrument maturity year	Oct. 1, 2021
Debt instrument interest percentage	7.25%
Note to DPL Capital Trust II Maturing in September 2031 - 8.125% [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 15.6	$ 15.6
Debt instrument maturity year	Sep. 1, 2031
Debt instrument interest percentage	8.125%

Debt Obligations (Current porti

Debt Obligations (Current portion - Long-term Debt) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Current portion - long-term debt	$ 149.5	$ 20.1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Current portion - long-term debt	114.5	0.1
Pollution Control Series Maturing in January 2028 - 4.70% [Member]
Debt Instrument [Line Items]
Current portion - long-term debt	$ 35.3	0
Debt instrument maturity year	Jan. 1, 2028
Debt instrument interest percentage	4.70%
Pollution Control Series Maturing in January 2028 - 4.70% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Current portion - long-term debt	$ 35.3	0
Pollution Control Series Maturing in January 2034 - 4.80% [Member]
Debt Instrument [Line Items]
Current portion - long-term debt	$ 79.1	0
Debt instrument maturity year	Jan. 1, 2034
Debt instrument interest percentage	4.80%
Pollution Control Series Maturing in January 2034 - 4.80% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Current portion - long-term debt	$ 79.1	0
Bank term loan due in May 2018 - rates from: 2.41% - 2.44% and 2.42% - 2.45% [Member]
Debt Instrument [Line Items]
Current portion - long-term debt	$ 35	$ 20
Debt instrument maturity year	May 1, 2018
Debt instrument interest percentage minimum	2.41%	2.42%
Debt instrument interest percentage maximum	2.44%	2.45%
U.S. Government note maturing in February 2061 - 4.20% [Member]
Debt Instrument [Line Items]
Current portion - long-term debt	$ 0.1	$ 0.1
Debt instrument maturity year	Feb. 1, 2061
Debt instrument interest percentage	4.20%
Debt instrument interest percentage minimum
U.S. Government note maturing in February 2061 - 4.20% [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt Instrument [Line Items]
Current portion - long-term debt	$ 0.1	$ 0.1

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Effective income tax rates	2.20%	(4.80%)	20.70%	(49.00%)
Estimated annual effective income tax rate			31.20%	(49.00%)
THE DAYTON POWER AND LIGHT COMPANY [Member]
Effective income tax rates	27.90%	30.20%	28.50%	29.90%
Estimated annual effective income tax rate			29.40%	30.40%

Pension and Postretirement Be47

Pension and Postretirement Benefits (Net Periodic Benefit Cost (Income)) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Contributions by employer			$ 0	$ 0
Pension [Member]
Service cost	$ 1,800,000	$ 1,500,000	3,600,000	3,000,000
Interest cost	4,300,000	4,400,000	8,600,000	8,800,000
Expected return on assets	(5,600,000)	(5,600,000)	(11,300,000)	(11,400,000)
Prior service cost	500,000	300,000	1,000,000	700,000
Actuarial loss / (gain)	1,400,000	800,000	2,900,000	1,700,000
Net periodic benefit cost	2,400,000	1,400,000	4,800,000	2,800,000
Postretirement [Member]
Service cost	0	0	0	100,000
Interest cost	100,000	200,000	300,000	400,000
Expected return on assets	0	0	0	(100,000)
Prior service cost	0	0	0	0
Actuarial loss / (gain)	(100,000)	(200,000)	(200,000)	(300,000)
Net periodic benefit cost	0	0	100,000	100,000
THE DAYTON POWER AND LIGHT COMPANY [Member]
Contributions by employer			0	0
THE DAYTON POWER AND LIGHT COMPANY [Member] | Pension [Member]
Service cost	1,700,000	1,400,000	3,500,000	2,900,000
Interest cost	4,300,000	4,300,000	8,600,000	8,700,000
Expected return on assets	(5,500,000)	(5,600,000)	(11,200,000)	(11,300,000)
Prior service cost	800,000	700,000	1,600,000	1,400,000
Actuarial loss / (gain)	2,400,000	1,600,000	4,800,000	3,200,000
Net periodic benefit cost	3,700,000	2,400,000	7,300,000	4,900,000
THE DAYTON POWER AND LIGHT COMPANY [Member] | Postretirement [Member]
Service cost	0	100,000	0	100,000
Interest cost	200,000	200,000	400,000	400,000
Expected return on assets	0	(100,000)	0	(100,000)
Prior service cost	0	0	0	0
Actuarial loss / (gain)	(100,000)	(100,000)	(300,000)	(300,000)
Net periodic benefit cost	$ 100,000	$ 100,000	$ 100,000	$ 100,000

Pension and Postretirement Be48

Pension and Postretirement Benefits (Estimated Future Benefit Payments and Medicare Part D Reimbursements) (Details) $ in Millions	Jun. 30, 2015USD ($)
Pension [Member]
2,015	$ 12.4
2,016	25.2
2,017	25.7
2,018	26.3
2,019	26.7
2020 - 2024	137
Postretirement [Member]
2,015	0.9
2,016	1.8
2,017	1.7
2,018	1.6
2,019	1.5
2020 - 2024	6.1
THE DAYTON POWER AND LIGHT COMPANY [Member] | Pension [Member]
2,015	12.4
2,016	25.2
2,017	25.7
2,018	26.3
2,019	26.7
2020 - 2024	137
THE DAYTON POWER AND LIGHT COMPANY [Member] | Postretirement [Member]
2,015	0.9
2,016	1.8
2,017	1.7
2,018	1.6
2,019	1.5
2020 - 2024	$ 6.1

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Long-term debt, earliest maturities	2,016
Long-term debt, latest maturities	2,061
Unrealized gains / (losses) on financial instruments, Amount before tax	$ 0.9		$ 0.8
Unrealized gains/(losses) on financial instruments, after tax	0.6		0.5
Realized gains on investments sold to facilitate the distribution of benefits	0.6
Realized gains on investments sold to facilitate the distribution of benefits, after tax	$ 0.4
Percent of inputs to the fair value of derivative instruments from quoted market prices (percent)	96.00%
Gross additions to our existing landfill and asbestos AROs	$ 39.8	$ 1.2
Gross additions to our ash pond AROs	$ 40.6
THE DAYTON POWER AND LIGHT COMPANY [Member]
Long-term debt, earliest maturities	2,016
Long-term debt, latest maturities	2,061
Realized gains on investments sold to facilitate the distribution of benefits	$ 0.6
Realized gains on investments sold to facilitate the distribution of benefits, after tax	0.4
Unrealized gains and immaterial unrealized losses in AOCI, before tax	1		1.1
Unrealized gains and immaterial unrealized losses in AOCI, after tax	$ 0.6		$ 0.7
Percent of inputs to the fair value of derivative instruments from quoted market prices (percent)	96.00%
Gross additions to our existing landfill and asbestos AROs	$ 39.8	$ 1.2
Gross additions to our ash pond AROs	$ 40.6

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value and Cost of Non-Derivative Instruments) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Carrying Value [Member]
Total Assets	$ 8.3	$ 8.7
Carrying Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Assets	8.3	8.7
Fair Value [Member]
Total Master Trust Assets, Fair Value	9.4	9.7
Total Assets	9.4	9.7
Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	9.4	9.7
Total Assets	9.4	9.7
Money Market Funds [Member] | Carrying Value [Member]
Total Master Trust Assets, Cost	0.2	0.1
Money Market Funds [Member] | Carrying Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Cost	0.2	0.1
Money Market Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.2	0.1
Money Market Funds [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.2	0.1
Equity Securities [Member] | Carrying Value [Member]
Total Master Trust Assets, Cost	2.7	2.7
Equity Securities [Member] | Carrying Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Cost	2.7	2.7
Equity Securities [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	3.7	3.7
Equity Securities [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	3.7	3.7
Debt Securities [Member] | Carrying Value [Member]
Total Master Trust Assets, Cost	4.5	4.7
Debt Securities [Member] | Carrying Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Cost	4.5	4.7
Debt Securities [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	4.5	4.7
Debt Securities [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	4.5	4.7
Hedge Funds [Member] | Carrying Value [Member]
Total Master Trust Assets, Cost	0.6	0.8
Hedge Funds [Member] | Carrying Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Cost	0.6	0.8
Hedge Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.7	0.8
Hedge Funds [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.7	0.8
Real Estate Funds [Member] | Carrying Value [Member]
Total Master Trust Assets, Cost	0.3	0.4
Real Estate Funds [Member] | Carrying Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Cost	0.3	0.4
Real Estate Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.3	0.4
Real Estate Funds [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.3	0.4
Debt [Member] | Carrying Value [Member]
Debt, Cost	2,159.8	2,159.7
Debt [Member] | Carrying Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt, Cost	877.2	877.1
Debt [Member] | Fair Value [Member]
Debt, Fair Value	2,235.3	2,204.8
Debt [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Debt, Fair Value	$ 883.1	$ 882.5

Fair Value Measurements (Fair51

Fair Value Measurements (Fair Value of Assets and Liabilities Measured on Recurring Basis) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Level 1 [Member]
Total Master Trust Assets, Fair Value	$ 0.2	$ 0.1
Total Assets	0.2	0.1
Total Derivative Liabilities	0.1	0.5
Total Liabilities	0.1	0.5
Level 1 [Member] | Commodity Contract - Heating Oil [Member]
Total Derivative Liabilities	0.1	0.4
Level 1 [Member] | Natural Gas [Member]
Total Derivative Liabilities		0.1
Level 1 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.2	0.1
Total Assets	0.2	0.1
Total Derivative Liabilities	0.1	0.5
Total Liabilities	0.1	0.5
Level 1 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - Heating Oil [Member]
Total Derivative Liabilities	0.1	0.4
Level 1 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Natural Gas [Member]
Total Derivative Liabilities		0.1
Level 2 [Member]
Total Master Trust Assets, Fair Value	9.2	9.6
Total Derivative Assets	18.8	13.7
Total Assets	28	23.3
Total Derivative Liabilities	17.7	11.1
Total Liabilities	2,235	2,197.7
Level 2 [Member] | Forward Contract Power [Member]
Total Derivative Assets	18.8	13.7
Total Derivative Liabilities	17.7	11.1
Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	9.2	9.6
Total Derivative Assets	19	13.9
Total Assets	28.2	23.5
Total Derivative Liabilities	17.9	11.2
Debt Instrument, Fair Value Disclosure	865.1	864.3
Total Liabilities	883	875.5
Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Total Derivative Assets	19	13.9
Total Derivative Liabilities	17.9	11.2
Level 3 [Member]
Total Derivative Assets	0.9	1.2
Total Assets	0.9	1.2
Total Derivative Liabilities	0.9	0.6
Total Liabilities	18.9	18.8
Level 3 [Member] | Commodity Contract - FTR [Member]
Total Derivative Assets	0.4
Total Derivative Liabilities	0.9	0.6
Level 3 [Member] | Forward Contract Power [Member]
Total Derivative Assets	0.5	1.2
Level 3 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Derivative Assets	0.9	1.2
Total Assets	0.9	1.2
Total Derivative Liabilities	0.9	0.6
Debt Instrument, Fair Value Disclosure	18	18.2
Total Liabilities	18.9	18.8
Level 3 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - FTR [Member]
Total Derivative Assets	0.4
Total Derivative Liabilities	0.9	0.6
Level 3 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Total Derivative Assets	0.5	1.2
Fair Value [Member]
Total Master Trust Assets, Fair Value	9.4	9.7
Total Derivative Assets	19.7	14.9
Total Assets	29.1	24.6
Total Derivative Liabilities	18.7	12.2
Total Liabilities	2,254	2,217
Fair Value [Member] | Commodity Contract - FTR [Member]
Total Derivative Assets	0.4
Total Derivative Liabilities	0.9	0.6
Fair Value [Member] | Forward Contract Power [Member]
Total Derivative Assets	19.3	14.9
Total Derivative Liabilities	17.7	11.1
Fair Value [Member] | Commodity Contract - Heating Oil [Member]
Total Derivative Liabilities	0.1	0.4
Fair Value [Member] | Natural Gas [Member]
Total Derivative Liabilities		0.1
Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	9.4	9.7
Total Derivative Assets	19.9	15.1
Total Assets	29.3	24.8
Total Derivative Liabilities	18.9	12.3
Debt Instrument, Fair Value Disclosure	883.1	882.5
Total Liabilities	902	894.8
Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - FTR [Member]
Total Derivative Assets	0.4
Total Derivative Liabilities	0.9	0.6
Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Total Derivative Assets	19.5	15.1
Total Derivative Liabilities	17.9	11.2
Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - Heating Oil [Member]
Total Derivative Liabilities	0.1	0.4
Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Natural Gas [Member]
Total Derivative Liabilities		0.1
Money Market Funds [Member] | Level 1 [Member]
Total Master Trust Assets, Fair Value	0.2	0.1
Money Market Funds [Member] | Level 1 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.2	0.1
Money Market Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.2	0.1
Money Market Funds [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.2	0.1
Equity Securities [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	3.7	3.7
Equity Securities [Member] | Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	3.7	3.7
Equity Securities [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	3.7	3.7
Equity Securities [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	3.7	3.7
Debt Securities [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	4.5	4.7
Debt Securities [Member] | Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	4.5	4.7
Debt Securities [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	4.5	4.7
Debt Securities [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	4.5	4.7
Hedge Funds [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	0.7	0.8
Hedge Funds [Member] | Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.7	0.8
Hedge Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.7	0.8
Hedge Funds [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.7	0.8
Real Estate Funds [Member] | Level 2 [Member]
Total Master Trust Assets, Fair Value	0.3	0.4
Real Estate Funds [Member] | Level 2 [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.3	0.4
Real Estate Funds [Member] | Fair Value [Member]
Total Master Trust Assets, Fair Value	0.3	0.4
Real Estate Funds [Member] | Fair Value [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Total Master Trust Assets, Fair Value	0.3	0.4
Debt [Member] | Level 2 [Member]
Debt Instrument, Fair Value Disclosure	2,217.3	2,186.6
Debt [Member] | Level 3 [Member]
Debt Instrument, Fair Value Disclosure	18	18.2
Debt [Member] | Fair Value [Member]
Debt Instrument, Fair Value Disclosure	$ 2,235.3	$ 2,204.8

Fair Value Measurements (Fair52

Fair Value Measurements (Fair Value of Assets and Liabilities Measured on a Nonrecurring Basis) (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Value	$ 2,547,800,000			$ 2,547,800,000		$ 2,517,600,000
Fixed asset impairment	0	$ 0		0	$ 11,500,000
Goodwill	317,000,000			317,000,000		$ 317,000,000
Goodwill impairment	$ 0	0		0	135,800,000
DPLER [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill		135,800,000			135,800,000
Goodwill impairment			$ 135,800,000	0	135,800,000
East Bend Station [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value			2,700,000
Carrying Value		14,200,000			14,200,000
Fixed asset impairment			$ 11,500,000	$ 0	11,500,000
Level 3 [Member] | East Bend Station [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value		$ 2,700,000			$ 2,700,000

Derivative Instruments and He53

Derivative Instruments and Hedging Activities (Narrative) (Details) $ in Millions	Jun. 30, 2015USD ($)
Fair value of commodity derivative instruments	$ 18.7
Collateral Already Posted, Aggregate Fair Value	7.4
Liability position offset by the asset position of counterparties with master netting agreements	9.6
Collateral if debt were to fall below investment grade	1.7
THE DAYTON POWER AND LIGHT COMPANY [Member]
Fair value of commodity derivative instruments	18.9
Collateral Already Posted, Aggregate Fair Value	7.4
Liability position offset by the asset position of counterparties with master netting agreements	9.6
Collateral if debt were to fall below investment grade	$ 1.9

Derivative Instruments and He54

Derivative Instruments and Hedging Activities (Outstanding Derivative Instruments) (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2015MWhgal	Dec. 31, 2014MWhMMBTUgal
THE DAYTON POWER AND LIGHT COMPANY [Member] | Natural Gas [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure		200,000
Not Designated as Hedging Instrument [Member] | Commodity Contract - FTR [Member]
Purchase of Units Derivative Instruments Financial Transmission Rights	24,200	10,500
Derivative, Nonmonetary Notional Amount MWh	24,200	10,500
Not Designated as Hedging Instrument [Member] | Commodity Contract - Heating Oil [Member]
Purchase of Volume Units Derivative Instruments Heating Oil Futures | gal	168,000	378,000
Derivative, Nonmonetary Notional Amount, Volume | gal	168,000	378,000
Not Designated as Hedging Instrument [Member] | Forward Contract Power [Member]
Purchase of Units Derivative Instruments Forward Power Contracts Not Designated as Hedged	3,621,900	1,725,200
Sales of Units Derivative Instruments Forward Power Contracts Not Designated as Hedged	(3,530,400)	(2,707,800)
Derivative, Nonmonetary Notional Amount MWh	91,500	(982,600)
Not Designated as Hedging Instrument [Member] | Natural Gas [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure		200,000
Not Designated as Hedging Instrument [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - FTR [Member]
Purchase of Units Derivative Instruments Financial Transmission Rights	24,200	10,500
Derivative, Nonmonetary Notional Amount MWh	24,200	10,500
Not Designated as Hedging Instrument [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - Heating Oil [Member]
Purchase of Volume Units Derivative Instruments Heating Oil Futures | gal	168,000	378,000
Derivative, Nonmonetary Notional Amount, Volume | gal	168,000	378,000
Not Designated as Hedging Instrument [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Purchase of Units Derivative Instruments Forward Power Contracts Not Designated as Hedged	3,621,900	1,725,200
Sales of Units Derivative Instruments Forward Power Contracts Not Designated as Hedged	(3,606,800)	(2,804,000)
Derivative, Nonmonetary Notional Amount MWh	15,100	(1,078,800)
Designated as Hedging Instrument [Member] | Forward Contract Power [Member]
Purchase of Units Derivative Instruments Forward Power Contracts Designated as Cash Flow Hedge	1,723,400	175,000
Sales of Units Derivative Instruments Forward Power Contracts Designated as Cash Flow Hedge	(8,809,400)	(2,991,000)
Derivative, Nonmonetary Notional Amount MWh	(7,086,000)	(2,816,000)
Designated as Hedging Instrument [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Purchase of Units Derivative Instruments Forward Power Contracts Designated as Cash Flow Hedge	1,723,400	175,000
Sales of Units Derivative Instruments Forward Power Contracts Designated as Cash Flow Hedge	(8,809,400)	(2,991,000)
Derivative, Nonmonetary Notional Amount MWh	(7,086,000)	(2,816,000)

Derivative Instruments and He55

Derivative Instruments and Hedging Activities (Gains or Losses Recognized in AOCI for the Cash Flow Hedges) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Beginning accumulated derivative gain / (loss) in AOCI	$ 1	$ (5.7)	$ 0.2	$ 1.4
Net gains / (losses) associated with current period hedging transactions	1.7	(12.1)	1.8	(25)
Ending accumulated derivative gain / (loss) in AOCI	1.1	(12.4)	1.1	(12.4)
Portion expected to be reclassified to earnings in the next twelve months	0.9		$ 0.9
Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months)			23 months
Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Beginning accumulated derivative gain / (loss) in AOCI	18.2	18.9	$ 18.3	19.2
Net gains / (losses) associated with current period hedging transactions	0	0
Ending accumulated derivative gain / (loss) in AOCI	17.8	18.8	17.8	18.8
Portion expected to be reclassified to earnings in the next twelve months	(0.6)		$ (0.6)
Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months)
THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Beginning accumulated derivative gain / (loss) in AOCI	1	(5.9)	$ 0.2	1
Net gains / (losses) associated with current period hedging transactions	1.7	(14.7)	1.8	(27.7)
Ending accumulated derivative gain / (loss) in AOCI	1.1	(14)	1.1	(14)
Portion expected to be reclassified to earnings in the next twelve months	0.9		$ 0.9
Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months)			23 months
THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Beginning accumulated derivative gain / (loss) in AOCI	2.4	4.9	$ 2.6	5.2
Net gains / (losses) associated with current period hedging transactions	0	0
Ending accumulated derivative gain / (loss) in AOCI	2.2	4.6	2.2	4.6
Portion expected to be reclassified to earnings in the next twelve months	(0.7)		$ (0.7)
Maximum length of time that we are hedging our exposure to variability in future cash flows related to forecasted transactions (in months)
Interest Expense [Member] | Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	0	0
Interest Expense [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	(0.4)	(0.1)	$ (0.5)	(0.4)
Interest Expense [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	0	0
Interest Expense [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	(0.2)	(0.3)	(0.4)	(0.6)
Revenue [Member] | Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	(1.9)	5.5	(2.1)	12
Revenue [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	0	0
Revenue [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	(1.9)	6.6	(2.1)	13.3
Revenue [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	0	0
Purchased Power [Member] | Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	0.3	(0.1)	1.2	(0.8)
Purchased Power [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	0	0
Purchased Power [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	0.3	0	$ 1.2	$ (0.6)
Purchased Power [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Interest Rate Contract [Member]
Accumulated Derivative Gain/Loss in AOCI [Roll Forward]
Net gains losses reclassified to earnings	$ 0	$ 0

Derivative Instruments and He56

Derivative Instruments and Hedging Activities (Classification within the Condensed Consolidated Statements of Results of Operations or Balance Sheets of the Gains and Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Change in unrealized gain / (loss)			$ (1.3)	$ (5.3)
Gain (Loss) on Derivative Instruments, Net, Pretax			(4.1)	(0.8)
Derivative, Gain (Loss) on Derivative, Net			(5.4)	(6.1)
THE DAYTON POWER AND LIGHT COMPANY [Member] | NYMEX Coal Contract [Member]
Change in unrealized gain / (loss)			0.1
Derivative, Gain (Loss) on Derivative, Net			(0.1)
THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - Heating Oil [Member]
Gain (Loss) on Derivative Instruments, Net, Pretax			0.8
Derivative, Gain (Loss) on Derivative, Net				(0.3)
Regulatory Asset [Member]
Derivative, Gain (Loss) on Derivative, Net			0.1
Not Designated as Hedging Instrument [Member]
Change in unrealized gain / (loss)	$ 0.5	$ 0.7
Gain (Loss) on Derivative Instruments, Net, Pretax	(1.6)	1.1
Derivative, Gain (Loss) on Derivative, Net	(1.1)	1.8	(5.4)	(6.1)
Not Designated as Hedging Instrument [Member] | Commodity Contract - FTR [Member]
Change in unrealized gain / (loss)	(0.8)	(1.2)	0.1	(1.5)
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0.6	(0.1)	0.6
Derivative, Gain (Loss) on Derivative, Net	(0.8)	(0.6)	0	(0.9)
Not Designated as Hedging Instrument [Member] | Commodity Contract - Heating Oil [Member]
Change in unrealized gain / (loss)	0.1	0.1	0.2	(0.1)
Gain (Loss) on Derivative Instruments, Net, Pretax	(0.1)	0	(0.1)	0.1
Derivative, Gain (Loss) on Derivative, Net		0.1	0.1
Not Designated as Hedging Instrument [Member] | Forward Contract Power [Member]
Change in unrealized gain / (loss)	1.2	1.8	(1.7)	(3.7)
Gain (Loss) on Derivative Instruments, Net, Pretax	(1.5)	0.5	(3.8)	(1.5)
Derivative, Gain (Loss) on Derivative, Net	(0.3)	2.3	(5.5)	(5.2)
Not Designated as Hedging Instrument [Member] | Natural Gas [Member]
Change in unrealized gain / (loss)			0.1
Gain (Loss) on Derivative Instruments, Net, Pretax			(0.1)
Not Designated as Hedging Instrument [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Change in unrealized gain / (loss)	0.4	1.3	(1.4)	(4.7)
Gain (Loss) on Derivative Instruments, Net, Pretax	(1.6)	1.2	(4.1)	(0.1)
Derivative, Gain (Loss) on Derivative, Net	(1.2)	2.5	(5.5)	(4.8)
Not Designated as Hedging Instrument [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - FTR [Member]
Change in unrealized gain / (loss)	(0.8)	(1.2)	0.1	(1.5)
Gain (Loss) on Derivative Instruments, Net, Pretax		0.6	(0.1)	0.6
Derivative, Gain (Loss) on Derivative, Net	(0.8)	(0.6)	0	(0.9)
Not Designated as Hedging Instrument [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - Heating Oil [Member]
Change in unrealized gain / (loss)	0.1	0.1	0.2	(0.1)
Gain (Loss) on Derivative Instruments, Net, Pretax	(0.1)		(0.1)	0.1
Derivative, Gain (Loss) on Derivative, Net	0	0.1	0.1
Not Designated as Hedging Instrument [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Change in unrealized gain / (loss)	1.1	2.4	(1.8)	(3.1)
Gain (Loss) on Derivative Instruments, Net, Pretax	(1.5)	0.6	(3.8)	(0.8)
Derivative, Gain (Loss) on Derivative, Net	(0.4)	3	(5.6)	(3.9)
Not Designated as Hedging Instrument [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Natural Gas [Member]
Change in unrealized gain / (loss)			0.1
Gain (Loss) on Derivative Instruments, Net, Pretax			(0.1)
Not Designated as Hedging Instrument [Member] | Regulatory Asset [Member] | Commodity Contract - FTR [Member]
Derivative, Gain (Loss) on Derivative, Net			0
Not Designated as Hedging Instrument [Member] | Regulatory Asset [Member] | Commodity Contract - Heating Oil [Member]
Derivative, Gain (Loss) on Derivative, Net			0.1
Not Designated as Hedging Instrument [Member] | Regulatory Asset [Member] | Forward Contract Power [Member]
Derivative, Gain (Loss) on Derivative, Net			0
Not Designated as Hedging Instrument [Member] | Regulatory Asset [Member] | Natural Gas [Member]
Derivative, Gain (Loss) on Derivative, Net			0
Not Designated as Hedging Instrument [Member] | Regulatory Asset [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative, Gain (Loss) on Derivative, Net			0.1
Not Designated as Hedging Instrument [Member] | Regulatory Asset [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - FTR [Member]
Derivative, Gain (Loss) on Derivative, Net			0
Not Designated as Hedging Instrument [Member] | Regulatory Asset [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - Heating Oil [Member]
Derivative, Gain (Loss) on Derivative, Net			0.1
Not Designated as Hedging Instrument [Member] | Regulatory Asset [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Derivative, Gain (Loss) on Derivative, Net			0
Not Designated as Hedging Instrument [Member] | Regulatory Asset [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Natural Gas [Member]
Derivative, Gain (Loss) on Derivative, Net			0
Not Designated as Hedging Instrument [Member] | Purchased Power [Member]
Derivative, Gain (Loss) on Derivative, Net	(3.6)	1.7	(7.7)	(6.1)
Not Designated as Hedging Instrument [Member] | Purchased Power [Member] | Commodity Contract - FTR [Member]
Derivative, Gain (Loss) on Derivative, Net	(0.8)	(0.6)	0	(0.9)
Not Designated as Hedging Instrument [Member] | Purchased Power [Member] | Forward Contract Power [Member]
Derivative, Gain (Loss) on Derivative, Net	(2.8)	2.3	(7.7)	(5.2)
Not Designated as Hedging Instrument [Member] | Purchased Power [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative, Gain (Loss) on Derivative, Net	(3.7)	1.7	(7.8)	(6.2)
Not Designated as Hedging Instrument [Member] | Purchased Power [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - FTR [Member]
Derivative, Gain (Loss) on Derivative, Net	(0.8)	(0.6)		(0.9)
Not Designated as Hedging Instrument [Member] | Purchased Power [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - Heating Oil [Member]
Derivative, Gain (Loss) on Derivative, Net	0	0
Not Designated as Hedging Instrument [Member] | Purchased Power [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Derivative, Gain (Loss) on Derivative, Net	(2.9)	2.3	(7.8)	(5.3)
Not Designated as Hedging Instrument [Member] | Revenue [Member]
Derivative, Gain (Loss) on Derivative, Net	2.5	0.1	2.2
Not Designated as Hedging Instrument [Member] | Revenue [Member] | Forward Contract Power [Member]
Derivative, Gain (Loss) on Derivative, Net	2.5		2.2
Not Designated as Hedging Instrument [Member] | Revenue [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative, Gain (Loss) on Derivative, Net	2.5	0.7	2.2	1.4
Not Designated as Hedging Instrument [Member] | Revenue [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - FTR [Member]
Derivative, Gain (Loss) on Derivative, Net	0	0
Not Designated as Hedging Instrument [Member] | Revenue [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - Heating Oil [Member]
Derivative, Gain (Loss) on Derivative, Net	0	0
Not Designated as Hedging Instrument [Member] | Revenue [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Derivative, Gain (Loss) on Derivative, Net	$ 2.5	0.7	$ 2.2	$ 1.4
Not Designated as Hedging Instrument [Member] | Fuel [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative, Gain (Loss) on Derivative, Net		0.1
Not Designated as Hedging Instrument [Member] | Fuel [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - FTR [Member]
Derivative, Gain (Loss) on Derivative, Net		0
Not Designated as Hedging Instrument [Member] | Fuel [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Commodity Contract - Heating Oil [Member]
Derivative, Gain (Loss) on Derivative, Net		0.1
Not Designated as Hedging Instrument [Member] | Fuel [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member] | Forward Contract Power [Member]
Derivative, Gain (Loss) on Derivative, Net		$ 0

Derivative Instruments and He57

Derivative Instruments and Hedging Activities (Fair Value and Balance Sheet Location (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Derivative Liability, Fair Value	$ 18.7
Liability position offset by the asset position of counterparties with master netting agreements	9.6
THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Liability, Fair Value	18.9
Liability position offset by the asset position of counterparties with master netting agreements	9.6
Total Assets [Member]
Derivative Asset, Fair Value	19.7	$ 14.9
Derivative, Collateral, Obligation to Return Securities	(9.6)	(6.6)
Derivative Asset, Fair Value, Amount Offset Against Collateral	10.1	8.3
Total Assets [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Asset, Fair Value	19.9	15.1
Derivative, Collateral, Obligation to Return Securities	(9.6)	(6.6)
Derivative Asset, Fair Value, Amount Offset Against Collateral	10.3	8.5
Total Liabilities [Member]
Derivative Liability, Fair Value	18.7	12.2
Derivative, Collateral, Right to Reclaim Securities	(9.6)	(6.6)
Derivative, Collateral, Right to Reclaim Cash	(7.4)	(4.9)
Liability position offset by the asset position of counterparties with master netting agreements	1.7	0.7
Total Liabilities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Liability, Fair Value	18.9	12.3
Derivative, Collateral, Right to Reclaim Securities	(9.6)	(6.6)
Derivative, Collateral, Right to Reclaim Cash	(7.4)	(4.9)
Liability position offset by the asset position of counterparties with master netting agreements	1.9	0.8
Cash Flow Hedging [Member] | Forward Contract Power [Member] | Short-term Derivative Positions [Member] | Other Prepayments and Current Assets [Member]
Derivative Asset, Fair Value	6.8	5.6
Derivative, Collateral, Obligation to Return Securities	(4.1)	(2)
Derivative Asset, Fair Value, Amount Offset Against Collateral	2.7	3.6
Cash Flow Hedging [Member] | Forward Contract Power [Member] | Short-term Derivative Positions [Member] | Other Prepayments and Current Assets [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Asset, Fair Value	6.8	5.6
Derivative, Collateral, Obligation to Return Securities	(4.1)	(2)
Derivative Asset, Fair Value, Amount Offset Against Collateral	2.7	3.6
Cash Flow Hedging [Member] | Forward Contract Power [Member] | Short-term Derivative Positions [Member] | Other Current Liabilities [Member]
Derivative Liability, Fair Value	5.3	2.1
Derivative, Collateral, Right to Reclaim Securities	(4.1)	(2)
Liability position offset by the asset position of counterparties with master netting agreements	1.2	0.1
Cash Flow Hedging [Member] | Forward Contract Power [Member] | Short-term Derivative Positions [Member] | Other Current Liabilities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Liability, Fair Value	5.3	2.1
Derivative, Collateral, Right to Reclaim Securities	(4.1)	(2)
Liability position offset by the asset position of counterparties with master netting agreements	1.2	0.1
Cash Flow Hedging [Member] | Forward Contract Power [Member] | Long-term Derivative Positions [Member] | Other Deferred Asset [Member]
Derivative Asset, Fair Value	2.7	0.3
Derivative, Collateral, Obligation to Return Securities	(1.4)	(0.3)
Derivative Asset, Fair Value, Amount Offset Against Collateral	1.3
Cash Flow Hedging [Member] | Forward Contract Power [Member] | Long-term Derivative Positions [Member] | Other Deferred Asset [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Asset, Fair Value	2.7	0.3
Derivative, Collateral, Obligation to Return Securities	(1.4)	(0.3)
Derivative Asset, Fair Value, Amount Offset Against Collateral	1.3
Cash Flow Hedging [Member] | Forward Contract Power [Member] | Long-term Derivative Positions [Member] | Other Deferred Credit [Member]
Derivative Liability, Fair Value	1.4	0.6
Derivative, Collateral, Right to Reclaim Securities	(1.4)	(0.3)
Derivative, Collateral, Right to Reclaim Cash		(0.3)
Cash Flow Hedging [Member] | Forward Contract Power [Member] | Long-term Derivative Positions [Member] | Other Deferred Credit [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Liability, Fair Value	1.4	0.6
Derivative, Collateral, Right to Reclaim Securities	(1.4)	(0.3)
Derivative, Collateral, Right to Reclaim Cash		(0.3)
Fair Value Hedging [Member] | Forward Contract Power [Member] | Short-term Derivative Positions [Member] | Other Prepayments and Current Assets [Member]
Derivative Asset, Fair Value	4.3	5.5
Derivative, Collateral, Obligation to Return Securities	(2.3)	(3.4)
Derivative Asset, Fair Value, Amount Offset Against Collateral	2	2.1
Fair Value Hedging [Member] | Forward Contract Power [Member] | Short-term Derivative Positions [Member] | Other Prepayments and Current Assets [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Asset, Fair Value	4.4	5.6
Derivative, Collateral, Obligation to Return Securities	(2.3)	(3.4)
Derivative Asset, Fair Value, Amount Offset Against Collateral	2.1	2.2
Fair Value Hedging [Member] | Forward Contract Power [Member] | Short-term Derivative Positions [Member] | Other Current Liabilities [Member]
Derivative Liability, Fair Value	9.6	7.5
Derivative, Collateral, Right to Reclaim Securities	(2.3)	(3.4)
Derivative, Collateral, Right to Reclaim Cash	(7.3)	(4.1)
Liability position offset by the asset position of counterparties with master netting agreements	0
Fair Value Hedging [Member] | Forward Contract Power [Member] | Short-term Derivative Positions [Member] | Other Current Liabilities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Liability, Fair Value	9.7	7.5
Derivative, Collateral, Right to Reclaim Securities	(2.3)	(3.4)
Derivative, Collateral, Right to Reclaim Cash	(7.3)	(4.1)
Liability position offset by the asset position of counterparties with master netting agreements	0.1
Fair Value Hedging [Member] | Forward Contract Power [Member] | Long-term Derivative Positions [Member] | Other Deferred Asset [Member]
Derivative Asset, Fair Value	5.5	3.5
Derivative, Collateral, Obligation to Return Securities	(1.4)	(0.9)
Derivative Asset, Fair Value, Amount Offset Against Collateral	4.1	2.6
Fair Value Hedging [Member] | Forward Contract Power [Member] | Long-term Derivative Positions [Member] | Other Deferred Asset [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Asset, Fair Value	5.6	3.6
Derivative, Collateral, Obligation to Return Securities	(1.4)	(0.9)
Derivative Asset, Fair Value, Amount Offset Against Collateral	4.2	2.7
Fair Value Hedging [Member] | Forward Contract Power [Member] | Long-term Derivative Positions [Member] | Other Deferred Credit [Member]
Derivative Liability, Fair Value	1.4	0.9
Derivative, Collateral, Right to Reclaim Securities	(1.4)	(0.9)
Fair Value Hedging [Member] | Forward Contract Power [Member] | Long-term Derivative Positions [Member] | Other Deferred Credit [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Liability, Fair Value	1.5	1
Derivative, Collateral, Right to Reclaim Securities	(1.4)	(0.9)
Liability position offset by the asset position of counterparties with master netting agreements	0.1	0.1
Fair Value Hedging [Member] | Commodity Contract - FTR [Member] | Short-term Derivative Positions [Member] | Other Prepayments and Current Assets [Member]
Derivative Asset, Fair Value	0.4
Derivative, Collateral, Obligation to Return Securities	(0.4)
Derivative Asset, Fair Value, Amount Offset Against Collateral	0
Fair Value Hedging [Member] | Commodity Contract - FTR [Member] | Short-term Derivative Positions [Member] | Other Prepayments and Current Assets [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Asset, Fair Value	0.4
Derivative, Collateral, Obligation to Return Securities	(0.4)
Fair Value Hedging [Member] | Commodity Contract - FTR [Member] | Short-term Derivative Positions [Member] | Other Current Liabilities [Member]
Derivative Liability, Fair Value	0.9	0.6
Derivative, Collateral, Right to Reclaim Securities	(0.4)
Liability position offset by the asset position of counterparties with master netting agreements	0.5	0.6
Fair Value Hedging [Member] | Commodity Contract - FTR [Member] | Short-term Derivative Positions [Member] | Other Current Liabilities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Liability, Fair Value	0.9	0.6
Derivative, Collateral, Right to Reclaim Securities	(0.4)
Liability position offset by the asset position of counterparties with master netting agreements	0.5	0.6
Fair Value Hedging [Member] | Commodity Contract - Heating Oil [Member] | Short-term Derivative Positions [Member] | Other Prepayments and Current Assets [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Asset, Fair Value, Amount Offset Against Collateral	0
Fair Value Hedging [Member] | Commodity Contract - Heating Oil [Member] | Short-term Derivative Positions [Member] | Other Current Liabilities [Member]
Derivative Liability, Fair Value	0.1	0.4
Derivative, Collateral, Right to Reclaim Cash	(0.1)	(0.4)
Fair Value Hedging [Member] | Commodity Contract - Heating Oil [Member] | Short-term Derivative Positions [Member] | Other Current Liabilities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Liability, Fair Value	0.1	0.4
Derivative, Collateral, Right to Reclaim Cash	$ (0.1)	(0.4)
Fair Value Hedging [Member] | Natural Gas [Member] | Short-term Derivative Positions [Member] | Other Current Liabilities [Member]
Derivative Liability, Fair Value		0.1
Derivative, Collateral, Right to Reclaim Cash		(0.1)
Fair Value Hedging [Member] | Natural Gas [Member] | Short-term Derivative Positions [Member] | Other Current Liabilities [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Derivative Liability, Fair Value		0.1
Derivative, Collateral, Right to Reclaim Cash		$ (0.1)

Contractual Obligations, Comm58

Contractual Obligations, Commercial Commitments and Contingencies (Narative) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Public Utility, Property, Plant and Equipment [Line Items]
Third party guarantees	$ 19.3
Due to third parties, current	$ 1.3
THE DAYTON POWER AND LIGHT COMPANY [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Debt maturity, earliest	2,018
Debt maturity, latest	2,040
Environmental reserves	$ 0.7	$ 0.8
DPLER [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Third party guarantees	2
DPLE [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Third party guarantees	$ 17.3
Debt Obligation on 4.9% Equity Ownership [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Equity ownership interest	4.90%
Equity ownership interest aggregate cost	$ 74.4
Electric Generation Company [Member] | THE DAYTON POWER AND LIGHT COMPANY [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Debt obligation	$ 1,518.7

Business Segments (Narrative) (

Business Segments (Narrative) (Details) - 6 months ended Jun. 30, 2015 mi² in Thousands, customer in Thousands	mi²customersegmentpower_plant
Segment Reporting Information [Line Items]
Number of operating segments | segment	2
Approximate number of competitive retail customers	133
THE DAYTON POWER AND LIGHT COMPANY [Member]
Segment Reporting Information [Line Items]
Number of coal fired power plants | power_plant	5
Approximate number of retail customers	516
Service area, square miles | mi²	6

Business Segments (Segment Fina

Business Segments (Segment Financial Information) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
External customer revenues	$ 372.9	$ 390.1	$ 867.4	$ 850.4
Total revenues	372.9	390.1	867.4	850.4
Fuel Costs	54.4	60.8	130.8	150.8
Purchased power	120.6	138.4	314.8	312.5
Amortization of intangibles		0.3	0	0.6
Gross margin	197.9	190.6	421.8	386.5
Depreciation and amortization	34.3	33.9	69.3	69.2
Goodwill impairment	0	0	0	135.8
Fixed asset impairment	0	0	0	11.5
Interest expense	30.9	31.9	61.4	62.7
Income tax expense (benefit)	0.5	(28.1)	13.2	70.7
Net income/ (loss)	21.7	33.8	50.4	(215.2)
Capital expenditures	31.1	26.8	64.8	55.2
Total assets	3,624.5		3,624.5		$ 3,577.8
Operating Segments [Member] | Utility [Member]
Segment Reporting Information [Line Items]
External customer revenues	283.8	254	634.4	546.6
Intersegment revenues	68.3	111.5	179	251
Total revenues	352.1	365.5	813.4	797.6
Fuel Costs	50.6	58.6	119.9	142.9
Purchased power	120.1	136.9	309.8	304.9
Gross margin	181.4	170	383.7	349.8
Depreciation and amortization	34.2	35.3	68.9	71.8
Interest expense	9	8.3	17.7	16.1
Income tax expense (benefit)	9.4	6	24.2	10
Net income/ (loss)	23.9	13.9	60.4	23.3
Capital expenditures	30.2	25.6	63.3	53
Total assets	3,377.7		3,377.7		3,338.7
Operating Segments [Member] | Competitive Retail [Member]
Segment Reporting Information [Line Items]
External customer revenues	75.2	125.2	197.5	273.6
Total revenues	75.2	125.2	197.5	273.6
Purchased power	68.7	111.1	180.4	251.3
Gross margin	6.5	14.1	17.1	22.3
Depreciation and amortization	0.1	0.2	0.4	0.3
Interest expense	0.1	0.1	0.1	0.2
Income tax expense (benefit)	(5.5)	1.3	(4.2)	0.6
Net income/ (loss)	6.7	2.6	8.3	1.2
Capital expenditures	0.1		0.3
Total assets	49.8		49.8		94.9
Other [Member]
Segment Reporting Information [Line Items]
External customer revenues	13.9	11	35.5	30.2
Intersegment revenues	1.3	0.1	2.9	1.1
Total revenues	15.2	11.1	38.4	31.3
Fuel Costs	3.8	2.2	10.9	7.9
Purchased power	0.6	1.3	4.8	6.7
Amortization of intangibles		0.3		0.6
Gross margin	10.8	7.3	22.7	16.1
Depreciation and amortization	0	(1.5)		(2.9)
Goodwill impairment				135.8
Fixed asset impairment				11.5
Interest expense	21.8	23.6	43.7	46.7
Income tax expense (benefit)	(3.4)	(35.3)	(6.8)	60.1
Net income/ (loss)	(8.9)	17.3	(18.3)	(239.7)
Capital expenditures	0.8	1.2	1.2	2.2
Total assets	1,480.4		1,480.4		1,440.1
Adjustments and Eliminations [Member]
Segment Reporting Information [Line Items]
External customer revenues	0	(0.1)		0
Intersegment revenues	(69.6)	(111.6)	(181.9)	(252.1)
Total revenues	(69.6)	(111.7)	(181.9)	(252.1)
Purchased power	(68.8)	(110.9)	(180.2)	(250.4)
Gross margin	(0.8)	(0.8)	(1.7)	(1.7)
Depreciation and amortization	0	(0.1)		0
Interest expense	0	(0.1)	(0.1)	(0.3)
Income tax expense (benefit)	0	(0.1)		$ 0
Net income/ (loss)	0	$ 0
Total assets	$ (1,283.4)		$ (1,283.4)		$ (1,295.9)

Goodwill Impairment (Narrative)

Goodwill Impairment (Narrative) (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014
Indefinite-lived Intangible Assets [Line Items]
Goodwill impairment	$ 0	$ 0		$ 0	$ 135,800,000
DPLER [Member]
Indefinite-lived Intangible Assets [Line Items]
Goodwill impairment			$ 135,800,000	$ 0	$ 135,800,000

Fixed-asset Impairment (Narrati

Fixed-asset Impairment (Narrative) (Details)	3 Months Ended			6 Months Ended
	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)MW	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)
Public Utility, Property, Plant and Equipment [Line Items]
Fixed asset impairment	$ 0	$ 0		$ 0	$ 11,500,000
East Bend Station [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Production plant capacity | MW			186
Fair value			$ 2,700,000
Fixed asset impairment			$ 11,500,000	$ 0	$ 11,500,000

Shareholder's Equity (Details)

Shareholder's Equity (Details) - $ / shares	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Common stock, shares authorized	1,500	1,500
Common stock, shares outstanding	1	1
THE DAYTON POWER AND LIGHT COMPANY [Member]
Class of Stock [Line Items]
Common stock, shares authorized	250,000,000
Par value common shares (in USD per share)	$ 0.01	$ 0.01
Common stock, shares outstanding	41,172,173
PUCO merger equity ratio approval (at least)	50.00%