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Regulatory Matters (Tables)

3 Months Ended

Mar. 31, 2021

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

			Alliant Energy												IPL												WPL
			March 31, 2021						December 31, 2020						March 31, 2021						December 31, 2020						March 31, 2021						December 31, 2020
Tax-related			$901						$890						$853						$843						$48						$47
Pension and OPEB costs			570						580						286						291						284						289
Asset retirement obligations			120						119						82						81						38						38
Assets retired early			108						113						74						77						34						36
IPL’s DAEC PPA amendment			108						110						108						110						—						—
WPL’s Western Wisconsin gas distribution expansion investments			55						55						—						—						55						55
Derivatives			13						26						6						13						7						13
Other			132						117						85						68						47						49
			$2,007						$2,010						$1,494						$1,483						$513						$527

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

			Alliant Energy												IPL												WPL
			March 31, 2021						December 31, 2020						March 31, 2021						December 31, 2020						March 31, 2021						December 31, 2020
Tax-related			$685						$732						$327						$331						$358						$401
Cost of removal obligations			371						367						242						238						129						129
Electric transmission cost recovery			67						68						40						39						27						29
WPL’s West Riverside liquidated damages			38						38						—						—						38						38
Derivatives			26						28						18						25						8						3
Other			68						73						34						43						34						30
			$1,255						$1,306						$661						$676						$594						$630

IPL [Member]

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

			Alliant Energy												IPL												WPL
			March 31, 2021						December 31, 2020						March 31, 2021						December 31, 2020						March 31, 2021						December 31, 2020
Tax-related			$901						$890						$853						$843						$48						$47
Pension and OPEB costs			570						580						286						291						284						289
Asset retirement obligations			120						119						82						81						38						38
Assets retired early			108						113						74						77						34						36
IPL’s DAEC PPA amendment			108						110						108						110						—						—
WPL’s Western Wisconsin gas distribution expansion investments			55						55						—						—						55						55
Derivatives			13						26						6						13						7						13
Other			132						117						85						68						47						49
			$2,007						$2,010						$1,494						$1,483						$513						$527

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

			Alliant Energy												IPL												WPL
			March 31, 2021						December 31, 2020						March 31, 2021						December 31, 2020						March 31, 2021						December 31, 2020
Tax-related			$685						$732						$327						$331						$358						$401
Cost of removal obligations			371						367						242						238						129						129
Electric transmission cost recovery			67						68						40						39						27						29
WPL’s West Riverside liquidated damages			38						38						—						—						38						38
Derivatives			26						28						18						25						8						3
Other			68						73						34						43						34						30
			$1,255						$1,306						$661						$676						$594						$630

WPL [Member]

Regulatory Assets [Line Items]

Regulatory Assets

Regulatory assets were comprised of the following items (in millions):

			Alliant Energy												IPL												WPL
			March 31, 2021						December 31, 2020						March 31, 2021						December 31, 2020						March 31, 2021						December 31, 2020
Tax-related			$901						$890						$853						$843						$48						$47
Pension and OPEB costs			570						580						286						291						284						289
Asset retirement obligations			120						119						82						81						38						38
Assets retired early			108						113						74						77						34						36
IPL’s DAEC PPA amendment			108						110						108						110						—						—
WPL’s Western Wisconsin gas distribution expansion investments			55						55						—						—						55						55
Derivatives			13						26						6						13						7						13
Other			132						117						85						68						47						49
			$2,007						$2,010						$1,494						$1,483						$513						$527

Regulatory Liabilities

Regulatory liabilities were comprised of the following items (in millions):

			Alliant Energy												IPL												WPL
			March 31, 2021						December 31, 2020						March 31, 2021						December 31, 2020						March 31, 2021						December 31, 2020
Tax-related			$685						$732						$327						$331						$358						$401
Cost of removal obligations			371						367						242						238						129						129
Electric transmission cost recovery			67						68						40						39						27						29
WPL’s West Riverside liquidated damages			38						38						—						—						38						38
Derivatives			26						28						18						25						8						3
Other			68						73						34						43						34						30
			$1,255						$1,306						$661						$676						$594						$630

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Tabular disclosure of assets that are created when regulatory agencies permit public utilities to defer certain costs included in rate-setting to the balance sheet.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 340
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382

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-Name Accounting Standards Codification
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Tabular disclosure of regulatory liabilities. Detailed information about liabilities that result from rate actions of a regulator. Rate actions of a regulator can impose a liability on a regulated enterprise resulting in a regulatory liability.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 980
-SubTopic 405
-Section 25
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-URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394

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