Goodwill And Other Intangible Assets (Estimated Amortization Expense) (Details) (USD $) In Millions	6 Months Ended
Jun. 30, 2011
2011	$ 11.7
2012	9.8
2013	7.7
2014	6.1
2015
WPL [Member]
2011	0.5
2012
2013
2014
2015
IPL [Member]
2011	11.2
2012	9.8
2013	7.7
2014	6.1
2015

- Definition

The amount of amortization expense expected to be recognized during the fifth twelve-month period following the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph a(3)

+ Details

Name:	us-gaap_FutureAmortizationExpenseYearFive
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of amortization expense expected to be recognized during the fourth twelve-month period following the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph a(3)

+ Details

Name:	us-gaap_FutureAmortizationExpenseYearFour
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of amortization expense expected to be recognized during the twelve-month period following the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph a(3)

+ Details

Name:	us-gaap_FutureAmortizationExpenseYearOne
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of amortization expense expected to be recognized during the third twelve-month period following the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph a(3)

+ Details

Name:	us-gaap_FutureAmortizationExpenseYearThree
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of amortization expense expected to be recognized during the second twelve-month period following the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 142
-Paragraph 45
-Subparagraph a(3)

+ Details

Name:	us-gaap_FutureAmortizationExpenseYearTwo
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration