Benefit Plans [Line Items]

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- Definition

Common stock percentage in assets held saving plans.

+ References

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- Definition

Deferred Compensation Plan, Base Salary And Incentive Compensation, Percentage

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- Definition

Defined Benefit Pension And Other Postretirement Benefits Plans, Total Plan Assets Percentage, On Common Stock

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- Definition

Defined Benefit Plan, Plan Asset Threshold for Long-term Allocation Targets

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- Definition

Percentage Of Employees Accepting Voluntary Separation Package

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- Definition

Performance Units Adjustment For Performance Multiplier Range Maximum

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- Definition

Performance Units Adjustment For Performance Multiplier Range Minimum

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Performance Period

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- Definition

Unrecognized cost of unvested share-based compensation awards.

+ 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

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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

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- Definition

Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b))
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747

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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Section 45
-Paragraph 28
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 5
-Section P
-Subsection 3, 4

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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

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Benefit Plans (Narrative) (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Benefit Plans [Line Items]
Total plan assets, percentage of common stock (less than 1%)	1.00%	1.00%
Common stock percentage in assets held in 401(k) saving plans	11.60%	12.60%
Percentage of employees accepting voluntary separation package	2.00%
Voluntary employee separation charges	$ 8.0
Unrecognized compensation cost	$ 3.9
Percentage of base salary and performance-based compensation	100.00%
Performance Shares and Units [Member]
Benefit Plans [Line Items]
Performance period	3 years
Performance Units [Member]
Benefit Plans [Line Items]
Performance multiplier range, lower	0.00%
Performance multiplier range, upper	200.00%
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] \| 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
IPL [Member]
Benefit Plans [Line Items]
Voluntary employee separation charges	$ 5.0
WPL [Member]
Benefit Plans [Line Items]
Voluntary employee separation charges	3.0
Other Postretirement Benefits Plans [Member]
Benefit Plans [Line Items]
Plan asset threshold for long-term allocation targets	5.0
Other Postretirement Benefits Plans [Member] \| IPL [Member]
Benefit Plans [Line Items]
Plan asset threshold for long-term allocation targets	5.0
Other Postretirement Benefits Plans [Member] \| WPL [Member]
Benefit Plans [Line Items]
Plan asset threshold for long-term allocation targets	$ 5.0
Omnibus Incentive Plan [Member]
Benefit Plans [Line Items]
Shares available for issuance under the Amended and Restated OIP	3.8