v2.4.0.6

Benefit Plans (Narrative) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2012 | Dec. 31, 2009 | Dec. 31, 2011
Benefit Plans [Line Items] |  |  |
Plan asset threshold for long-term allocation targets | $ 5 |  |
Total plan assets, percentage of common stock (less than 1%) | 1.00% |  | 1.00%
Interest crediting rate, percentage above annual change in consumer price index |  | 3.00% |
Common stock percentage in assets held saving plans | 12.50% |  | 14.60%
Unrecognized compensation cost | 6.1 |  |
Weighted average remaining contractual term | 1 year |  |
Intrinsic value of options outstanding and exercisable | 0.5 |  |
Percentage of base salary and performance-based compensation | 100.00% |  |
Performance Shares and Units [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Performance period | 3 years |  |
Expected volatility based on historical daily stock prices, historical period | 3 years |  |
Performance Shares [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Performance multiplier range, lower | 0.00% |  |
Performance multiplier range, upper | 200.00% |  |
Performance Units [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Performance multiplier range, lower | 0.00% |  |
Performance multiplier range, upper | 200.00% |  |
Non-Qualified Stock Options [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Vesting period | 3 years |  |
Expiration period | 10 years |  |
Minimum [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Unrecognized compensation cost recognized over a weighted average period | 1 year |  |
Minimum [Member] | Performance-Contingent Restricted Stock [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Performance period | 2 years |  |
Minimum [Member] | Performance Contingent Cash Awards [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Performance period | 2 years |  |
Maximum [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Unrecognized compensation cost recognized over a weighted average period | 2 years |  |
Maximum [Member] | Time-Based Restricted Stock [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Vesting period | 3 years |  |
Maximum [Member] | Performance-Contingent Restricted Stock [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Performance period | 4 years |  |
Maximum [Member] | Performance Contingent Cash Awards [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Performance period | 4 years |  |
Omnibus Incentive Plan [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Shares available for issuance under the OIP | 4.2 |  |
IPL [Member] | Allocated From Corporate Services [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Estimated amortization | 1.3 |  |
WPL [Member] | Allocated From Corporate Services [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Estimated amortization | $ 0.9 |  |
U.S. Currency [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Securities lending, initial collateral levels | 102.00% |  |
Other Securities [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Securities lending, initial collateral levels | 102.00% |  |
Foreign Currency [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Securities lending, initial collateral levels | 105.00% |  |
Non Affiliated Borrowers [Member] | U.S. Currency [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Securities lending, initial collateral levels | 100.00% |  |
Affiliated Borrowers [Member] | U.S. Currency [Member] |  |  |
Benefit Plans [Line Items] |  |  |
Securities lending, initial collateral levels | 102.00% |  |

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- Definition Common stock percentage in assets held saving plans. + References No definition available. + Details
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- Definition Deferred Compensation Plan, Base Salary And Incentive Compensation, Percentage + References No definition available. + Details
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- Definition Defined Benefit Pension And Other Postretirement Benefits Plans, Total Plan Assets Percentage, On Common Stock + References No definition available. + Details
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- Definition Defined Benefit Plan, Plan Asset Threshold for Long-term Allocation Targets + References No definition available. + Details
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- Definition The aggregate amount in accumulated other comprehensive income expected to be recognized as a component of net periodic benefit cost over the fiscal year that follows the most recent annual statement of financial position presented, including the net gain (loss), net prior service cost or credit, and net transition asset or obligation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (s) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 158 -Paragraph 7 -Subparagraph d -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph s -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph h -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of options outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph d(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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