XML 50 R27.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Revenues Revenues (Tables) | 3 Months Ended
--- | ---
Mar. 31, 2018
Disaggregation of Revenue [Line Items] |
Disaggregation of Revenue | Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Three Months Ended March 31 | 2018 |  | 2017 |  | 2018 |  | 2017 |  | 2018 |  | 2017
Electric Utility: |  |  |  |  |  |  |  |  |  |  |
Retail - residential |  | $259.4 |  |  |  | $241.2 |  |  |  | $142.2 |  |  |  | $123.3 |  |  |  | $117.2 |  |  |  | $117.9 |
Retail - commercial | 174.0 |  |  | 165.7 |  |  | 111.6 |  |  | 99.5 |  |  | 62.4 |  |  | 66.2 |
Retail - industrial | 201.9 |  |  | 195.0 |  |  | 114.8 |  |  | 103.9 |  |  | 87.1 |  |  | 91.1 |
Wholesale | 53.8 |  |  | 63.4 |  |  | 24.3 |  |  | 21.3 |  |  | 29.5 |  |  | 42.1 |
Bulk power and other | 19.6 |  |  | 12.3 |  |  | 12.8 |  |  | 8.2 |  |  | 6.8 |  |  | 4.1 |
Total Electric Utility | 708.7 |  |  | 677.6 |  |  | 405.7 |  |  | 356.2 |  |  | 303.0 |  |  | 321.4 |
Gas Utility: |  |  |  |  |  |  |  |  |  |  |
Retail - residential | 110.6 |  |  | 89.9 |  |  | 65.5 |  |  | 47.9 |  |  | 45.1 |  |  | 42.0 |
Retail - commercial | 57.0 |  |  | 49.8 |  |  | 31.6 |  |  | 25.8 |  |  | 25.4 |  |  | 24.0 |
Retail - industrial | 5.8 |  |  | 4.8 |  |  | 2.7 |  |  | 2.8 |  |  | 3.1 |  |  | 2.0 |
Transportation/other | 12.2 |  |  | 9.8 |  |  | 8.3 |  |  | 6.6 |  |  | 3.9 |  |  | 3.2 |
Total Gas Utility | 185.6 |  |  | 154.3 |  |  | 108.1 |  |  | 83.1 |  |  | 77.5 |  |  | 71.2 |
Other Utility: |  |  |  |  |  |  |  |  |  |  |
Steam | 9.4 |  |  | 8.6 |  |  | 9.4 |  |  | 8.6 |  |  | — |  |  | — |
Other utility | 3.8 |  |  | 3.1 |  |  | 2.6 |  |  | 2.6 |  |  | 1.2 |  |  | 0.5 |
Total Other Utility | 13.2 |  |  | 11.7 |  |  | 12.0 |  |  | 11.2 |  |  | 1.2 |  |  | 0.5 |
Non-Utility and Other: |  |  |  |  |  |  |  |  |  |  |
Transportation and other | 8.8 |  |  | 10.3 |  |  | — |  |  | — |  |  | — |  |  | — |
Total Non-Utility and Other | 8.8 |  |  | 10.3 |  |  | — |  |  | — |  |  | — |  |  | — |
Total revenues |  | $916.3 |  |  |  | $853.9 |  |  |  | $525.8 |  |  |  | $450.5 |  |  |  | $381.7 |  |  |  | $393.1 |
IPL [Member] |
Disaggregation of Revenue [Line Items] |
Disaggregation of Revenue | Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Three Months Ended March 31 | 2018 |  | 2017 |  | 2018 |  | 2017 |  | 2018 |  | 2017
Electric Utility: |  |  |  |  |  |  |  |  |  |  |
Retail - residential |  | $259.4 |  |  |  | $241.2 |  |  |  | $142.2 |  |  |  | $123.3 |  |  |  | $117.2 |  |  |  | $117.9 |
Retail - commercial | 174.0 |  |  | 165.7 |  |  | 111.6 |  |  | 99.5 |  |  | 62.4 |  |  | 66.2 |
Retail - industrial | 201.9 |  |  | 195.0 |  |  | 114.8 |  |  | 103.9 |  |  | 87.1 |  |  | 91.1 |
Wholesale | 53.8 |  |  | 63.4 |  |  | 24.3 |  |  | 21.3 |  |  | 29.5 |  |  | 42.1 |
Bulk power and other | 19.6 |  |  | 12.3 |  |  | 12.8 |  |  | 8.2 |  |  | 6.8 |  |  | 4.1 |
Total Electric Utility | 708.7 |  |  | 677.6 |  |  | 405.7 |  |  | 356.2 |  |  | 303.0 |  |  | 321.4 |
Gas Utility: |  |  |  |  |  |  |  |  |  |  |
Retail - residential | 110.6 |  |  | 89.9 |  |  | 65.5 |  |  | 47.9 |  |  | 45.1 |  |  | 42.0 |
Retail - commercial | 57.0 |  |  | 49.8 |  |  | 31.6 |  |  | 25.8 |  |  | 25.4 |  |  | 24.0 |
Retail - industrial | 5.8 |  |  | 4.8 |  |  | 2.7 |  |  | 2.8 |  |  | 3.1 |  |  | 2.0 |
Transportation/other | 12.2 |  |  | 9.8 |  |  | 8.3 |  |  | 6.6 |  |  | 3.9 |  |  | 3.2 |
Total Gas Utility | 185.6 |  |  | 154.3 |  |  | 108.1 |  |  | 83.1 |  |  | 77.5 |  |  | 71.2 |
Other Utility: |  |  |  |  |  |  |  |  |  |  |
Steam | 9.4 |  |  | 8.6 |  |  | 9.4 |  |  | 8.6 |  |  | — |  |  | — |
Other utility | 3.8 |  |  | 3.1 |  |  | 2.6 |  |  | 2.6 |  |  | 1.2 |  |  | 0.5 |
Total Other Utility | 13.2 |  |  | 11.7 |  |  | 12.0 |  |  | 11.2 |  |  | 1.2 |  |  | 0.5 |
Non-Utility and Other: |  |  |  |  |  |  |  |  |  |  |
Transportation and other | 8.8 |  |  | 10.3 |  |  | — |  |  | — |  |  | — |  |  | — |
Total Non-Utility and Other | 8.8 |  |  | 10.3 |  |  | — |  |  | — |  |  | — |  |  | — |
Total revenues |  | $916.3 |  |  |  | $853.9 |  |  |  | $525.8 |  |  |  | $450.5 |  |  |  | $381.7 |  |  |  | $393.1 |
WPL [Member] |
Disaggregation of Revenue [Line Items] |
Disaggregation of Revenue | Disaggregation of revenues from contracts with customers, which correlates to revenues for each reportable segment, was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
Three Months Ended March 31 | 2018 |  | 2017 |  | 2018 |  | 2017 |  | 2018 |  | 2017
Electric Utility: |  |  |  |  |  |  |  |  |  |  |
Retail - residential |  | $259.4 |  |  |  | $241.2 |  |  |  | $142.2 |  |  |  | $123.3 |  |  |  | $117.2 |  |  |  | $117.9 |
Retail - commercial | 174.0 |  |  | 165.7 |  |  | 111.6 |  |  | 99.5 |  |  | 62.4 |  |  | 66.2 |
Retail - industrial | 201.9 |  |  | 195.0 |  |  | 114.8 |  |  | 103.9 |  |  | 87.1 |  |  | 91.1 |
Wholesale | 53.8 |  |  | 63.4 |  |  | 24.3 |  |  | 21.3 |  |  | 29.5 |  |  | 42.1 |
Bulk power and other | 19.6 |  |  | 12.3 |  |  | 12.8 |  |  | 8.2 |  |  | 6.8 |  |  | 4.1 |
Total Electric Utility | 708.7 |  |  | 677.6 |  |  | 405.7 |  |  | 356.2 |  |  | 303.0 |  |  | 321.4 |
Gas Utility: |  |  |  |  |  |  |  |  |  |  |
Retail - residential | 110.6 |  |  | 89.9 |  |  | 65.5 |  |  | 47.9 |  |  | 45.1 |  |  | 42.0 |
Retail - commercial | 57.0 |  |  | 49.8 |  |  | 31.6 |  |  | 25.8 |  |  | 25.4 |  |  | 24.0 |
Retail - industrial | 5.8 |  |  | 4.8 |  |  | 2.7 |  |  | 2.8 |  |  | 3.1 |  |  | 2.0 |
Transportation/other | 12.2 |  |  | 9.8 |  |  | 8.3 |  |  | 6.6 |  |  | 3.9 |  |  | 3.2 |
Total Gas Utility | 185.6 |  |  | 154.3 |  |  | 108.1 |  |  | 83.1 |  |  | 77.5 |  |  | 71.2 |
Other Utility: |  |  |  |  |  |  |  |  |  |  |
Steam | 9.4 |  |  | 8.6 |  |  | 9.4 |  |  | 8.6 |  |  | — |  |  | — |
Other utility | 3.8 |  |  | 3.1 |  |  | 2.6 |  |  | 2.6 |  |  | 1.2 |  |  | 0.5 |
Total Other Utility | 13.2 |  |  | 11.7 |  |  | 12.0 |  |  | 11.2 |  |  | 1.2 |  |  | 0.5 |
Non-Utility and Other: |  |  |  |  |  |  |  |  |  |  |
Transportation and other | 8.8 |  |  | 10.3 |  |  | — |  |  | — |  |  | — |  |  | — |
Total Non-Utility and Other | 8.8 |  |  | 10.3 |  |  | — |  |  | — |  |  | — |  |  | — |
Total revenues |  | $916.3 |  |  |  | $853.9 |  |  |  | $525.8 |  |  |  | $450.5 |  |  |  | $381.7 |  |  |  | $393.1 |

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 Tabular disclosure of disaggregation of revenue into categories depicting how nature, amount, timing, and uncertainty of revenue and cash flows are affected by economic factor. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=82913847&loc=SL49130545-203045 + Details
Name: | us-gaap_DisaggregationOfRevenueTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
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: |