Stock-Based Compensation Plans (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation costs	$ 98	$ 105	$ 89
Stock-based compensation costs capitalized	37	38	32
Incentive Plans \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation costs	49	62	46
Incentive Plans \| Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation costs	1	2	2
Incentive Plans \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation costs	0	(3)	0
401(k) Savings Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation costs	42	39	38
EDCP & DCPD
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation costs	6	5	3
FES
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation costs	7	16	11
Stock-based compensation costs capitalized	1	2	1
FES \| Incentive Plans \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation costs	4	11	6
FES \| 401(k) Savings Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation costs	$ 3	$ 5	$ 5

Represents the compensation cost capitalized during the period arising from equity-based compensation arrangements (for example, shares of stock, units, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

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+ References

No definition available.

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- Definition

Amount of capitalized and expensed compensation cost from equity-based compensation arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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