XML 66 R46.htm IDEA: XBRL DOCUMENT
v3.21.1

Revenue (Disaggregation of Revenues) (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2021 | Mar. 31, 2020
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | $ 901 | $ 916
Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 701 | 730
Electric [Member] | Retail - residential [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 262 | 266
Electric [Member] | Retail - commercial [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 172 | 183
Electric [Member] | Retail - industrial [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 202 | 210
Electric [Member] | Wholesale [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 40 | 40
Electric [Member] | Other [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 25 | 31
Gas [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 170 | 152
Gas [Member] | Retail - residential [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 99 | 91
Gas [Member] | Retail - commercial [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 53 | 45
Gas [Member] | Retail - industrial [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 5 | 4
Gas [Member] | Other [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 13 | 12
Other Utility [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 13 | 12
Other Utility [Member] | Steam [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 9 | 10
Other Utility [Member] | Other [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 4 | 2
Non-utility and Other [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 17 | 22
Non-utility and Other [Member] | Transportation and other [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 17 | 22
IPL [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 489 | 519
IPL [Member] | Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 386 | 425
IPL [Member] | Electric [Member] | Retail - residential [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 139 | 147
IPL [Member] | Electric [Member] | Retail - commercial [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 110 | 120
IPL [Member] | Electric [Member] | Retail - industrial [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 112 | 121
IPL [Member] | Electric [Member] | Wholesale [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 11 | 14
IPL [Member] | Electric [Member] | Other [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 14 | 23
IPL [Member] | Gas [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 91 | 83
IPL [Member] | Gas [Member] | Retail - residential [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 52 | 49
IPL [Member] | Gas [Member] | Retail - commercial [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 27 | 24
IPL [Member] | Gas [Member] | Retail - industrial [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 3 | 2
IPL [Member] | Gas [Member] | Other [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 9 | 8
IPL [Member] | Other Utility [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 12 | 11
IPL [Member] | Other Utility [Member] | Steam [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 9 | 10
IPL [Member] | Other Utility [Member] | Other [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 3 | 1
WPL [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 395 | 375
WPL [Member] | Electric [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 315 | 305
WPL [Member] | Electric [Member] | Retail - residential [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 123 | 119
WPL [Member] | Electric [Member] | Retail - commercial [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 62 | 63
WPL [Member] | Electric [Member] | Retail - industrial [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 90 | 89
WPL [Member] | Electric [Member] | Wholesale [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 29 | 26
WPL [Member] | Electric [Member] | Other [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 11 | 8
WPL [Member] | Gas [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 79 | 69
WPL [Member] | Gas [Member] | Retail - residential [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 47 | 42
WPL [Member] | Gas [Member] | Retail - commercial [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 26 | 21
WPL [Member] | Gas [Member] | Retail - industrial [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 2 | 2
WPL [Member] | Gas [Member] | Other [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 4 | 4
WPL [Member] | Other Utility [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | 1 | 1
WPL [Member] | Other Utility [Member] | Other [Member] |  |
Disaggregation of Revenue [Line Items] |  |
Revenue from contracts with customers | $ 1 | $ 1

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_DisaggregationOfRevenueLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 30 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8906-108599 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 40 -URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9031-108599 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 41 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9038-108599 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 32 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 32 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130543-203045 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 42 -URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9054-108599 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130545-203045 Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 924 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 11.L) -URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856 + Details
Name: | us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Details
Name: | srt_MajorCustomersAxis=lnt_RetailResidentialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=lnt_RetailCommercialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=lnt_RetailIndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=lnt_WholesaleMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MajorCustomersAxis=us-gaap_OtherCustomerMember
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: | srt_MajorCustomersAxis=lnt_SteamMember
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: |

X
- Details
Name: | srt_MajorCustomersAxis=lnt_TransportationandOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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: |