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Regulatory Matters (Regulatory Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 1,306	$ 1,424
Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	732	836
Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	367	388
Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	68	88
West Riverside liquidated damages [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	38	0
Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	28	20
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	73	92
IPL [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	676	715
IPL [Member] | Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	331	351
IPL [Member] | Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	238	257
IPL [Member] | Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	39	51
IPL [Member] | Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	25	17
IPL [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	43	39
WPL [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	630	709
WPL [Member] | Tax-related [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	401	485
WPL [Member] | Cost of removal obligations [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	129	131
WPL [Member] | Electric transmission cost recovery [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	29	37
WPL [Member] | West Riverside liquidated damages [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	38	0
WPL [Member] | Derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	3	3
WPL [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 30	$ 53

X

- Definition

The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 405
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394

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- Definition

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+ References

No definition available.

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