XML 177 R82.htm IDEA: XBRL DOCUMENT v2.4.1.9

Common Equity (Schedule of Capital Contributions) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
IPL [Member]
Capital contributions from parent	$ 90.0us-gaap_ProceedsFromContributionsFromParent / dei_LegalEntityAxis = lnt_IplMember	$ 120.0us-gaap_ProceedsFromContributionsFromParent / dei_LegalEntityAxis = lnt_IplMember	$ 110.0us-gaap_ProceedsFromContributionsFromParent / dei_LegalEntityAxis = lnt_IplMember
WPL [Member]
Capital contributions from parent	0us-gaap_ProceedsFromContributionsFromParent / dei_LegalEntityAxis = lnt_WplMember	0us-gaap_ProceedsFromContributionsFromParent / dei_LegalEntityAxis = lnt_WplMember	90.0us-gaap_ProceedsFromContributionsFromParent / dei_LegalEntityAxis = lnt_WplMember
Corporate Services [Member]
Capital contributions from parent	$ 0us-gaap_ProceedsFromContributionsFromParent / dei_LegalEntityAxis = lnt_CorporateServicesMember	$ 0us-gaap_ProceedsFromContributionsFromParent / dei_LegalEntityAxis = lnt_CorporateServicesMember	$ 30.0us-gaap_ProceedsFromContributionsFromParent / dei_LegalEntityAxis = lnt_CorporateServicesMember

X

- Definition

The cash inflow from parent as a source of financing that is recorded as additional paid in capital.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	dei_LegalEntityAxis=lnt_CorporateServicesMember
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: