Defined Benefit Plan, Current and Future Contributions Made in Current Year

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- Definition

Defined Benefit Plan, Net Periodic Benefit Cost, Excluding Capitalized Amounts

+ References

No definition available.

+ Details

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- Definition

Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan.

+ References

+ Details

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- Definition

Amount of contribution received by defined benefit plan from employer which increases plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(5)(ii)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2709-114920

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(5)(iv)(01)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan.

+ References

+ Details

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- Definition

Amount of cost recognized for passage of time related to defined benefit plan.

+ References

+ Details

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- Definition

Amount of net periodic benefit cost (credit) for defined benefit plan.

+ References

+ Details

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- Definition

Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

+ References

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Pension and Other Postemployment Benefits (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Jan. 31, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Additional funding contributions	$ 750
Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs		$ 56	$ 52	$ 112	$ 104
Interest costs		93	97	186	194
Expected return on plan assets		(144)	(112)	(288)	(224)
Amortization of prior service costs (credits)		2	2	4	4
Net periodic costs (credits)		7	39	14	78
Pension \| FES and FENOC \| Discontinued Operations, Disposed of by Means Other than Sale
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic costs (credits)		13	15	26	31
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service costs		1	1	2	2
Interest costs		6	7	12	14
Expected return on plan assets		(7)	(7)	(15)	(15)
Amortization of prior service costs (credits)		(20)	(20)	(40)	(40)
Net periodic costs (credits)		(20)	(19)	(41)	(39)
OPEB \| FES and FENOC \| Discontinued Operations, Disposed of by Means Other than Sale
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic costs (credits)		(10)	(8)	(20)	(16)
FirstEnergy \| Pension
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit expense (credit)		(18)	27	(32)	59
FirstEnergy \| OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit expense (credit)		$ (21)	$ (14)	$ (42)	$ (29)
Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions by employer	$ 500