XML 112 R80.htm IDEA: XBRL DOCUMENT
v3.3.1.900

Common Equity (Schedule Of Restricted Net Assets of Subsidiaries) (Details) - USD ($) $ in Billions | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | ---
IPL [Member] |  |
Restricted net assets of subsidiaries | $ 1.4 | $ 1.3
WPL [Member] |  |
Restricted net assets of subsidiaries | $ 1.6 | $ 1.6

X
- Definition Amount of restricted net assets of consolidated and unconsolidated subsidiaries as of the end of the most recently completed fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(e)(3)(ii)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph e -Subparagraph 3 -Article 4 + Details
Name: | us-gaap_AmountOfRestrictedNetAssetsForConsolidatedAndUnconsolidatedSubsidiaries
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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: |