XML 88 R68.htm IDEA: XBRL DOCUMENT
v3.20.2

Segments Of Business (Schedule Of Segments Of Business) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Segment Reporting Information [Line Items] |  |  |  |
Revenues | $ 920 | $ 990 | $ 2,599 | $ 2,768
Operating income (loss) | 272 | 290 | 628 | 617
Net income attributable to common shareowners | 246 | 226 | 550 | 446
Net income | 249 | 229 | 558 | 454
IPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 553 | 597 | 1,504 | 1,593
Operating income (loss) | 162 | 174 | 347 | 322
Net income attributable to common shareowners | 148 | 141 | 290 | 239
Net income | 151 | 144 | 298 | 247
WPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 351 | 372 | 1,038 | 1,113
Operating income (loss) | 89 | 108 | 255 | 273
Net income | 73 | 76 | 220 | 183
Electric [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 852 | 916 | 2,257 | 2,350
Operating income (loss) | 251 | 284 | 549 | 543
Electric [Member] | IPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 519 | 561 | 1,332 | 1,373
Operating income (loss) | 159 | 175 | 308 | 291
Electric [Member] | WPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 333 | 355 | 925 | 977
Operating income (loss) | 92 | 109 | 241 | 252
Gas [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 42 | 42 | 253 | 323
Operating income (loss) | (1) | (5) | 48 | 47
Gas [Member] | IPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 24 | 25 | 141 | 188
Operating income (loss) | 1 | (4) | 34 | 26
Gas [Member] | WPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 18 | 17 | 112 | 135
Operating income (loss) | (2) | (1) | 14 | 21
Other Utility [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 10 | 11 | 32 | 33
Operating income (loss) | 1 | 3 | 5 | 5
Other Utility [Member] | IPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 10 | 11 | 31 | 32
Operating income (loss) | 2 | 3 | 5 | 5
Other Utility [Member] | WPL [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 0 | 0 | 1 | 1
Operating income (loss) | (1) | 0 | 0 | 0
Utility Business [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 904 | 969 | 2,542 | 2,706
Operating income (loss) | 251 | 282 | 602 | 595
Net income attributable to common shareowners | 221 | 217 | 510 | 422
Non-Utility [Member] | ATC Holdings, Non-Utility, Parent and Other [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 16 | 21 | 57 | 62
Operating income (loss) | 21 | 8 | 26 | 22
Net income attributable to common shareowners | $ 25 | $ 9 | $ 40 | $ 24

X
- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669619-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(22)) -URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1B -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669625-108580 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(18)) -URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(20)) -URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
Name: | us-gaap_NetIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=117326831&loc=d3e1377-109256 + Details
Name: | us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The net result for the period of deducting operating expenses from operating revenues. + References No definition available. + Details
Name: | us-gaap_OperatingIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The total amount of operating revenues recognized during the period. + References No definition available. + Details
Name: | us-gaap_RegulatedAndUnregulatedOperatingRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- 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
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=lnt_IplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=lnt_WplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=lnt_ElectricMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=lnt_GasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=lnt_OtherUtilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=lnt_UtilityBusinessMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityRegulatedOrUnregulatedStatusAxis=us-gaap_UnregulatedOperationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=us-gaap_AllOtherSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |