Agreement Term Of Extension

No definition available.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

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- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

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Debt (Narrative) (Details) - USD ($)	1 Months Ended				9 Months Ended
Debt (Narrative) (Details) - USD ($)	Sep. 30, 2019	Jul. 31, 2019	Jun. 30, 2019	Apr. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Debt [Line Items]
Credit facility agreement, extension					1 year
Line of credit facility, current borrowing capacity	$ 1,000,000,000				$ 1,000,000,000
Payments to retire long-term debt					253,500,000	$ 603,100,000
IPL [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	250,000,000				250,000,000
Payments to retire long-term debt					0	100,000,000.0
WPL [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	$ 300,000,000				300,000,000
Payments to retire long-term debt					$ 250,000,000.0	$ 0
Senior Debentures [Member] \| 3.6% senior debentures due 2029 [Member] \| IPL [Member]
Debt [Line Items]
Proceeds from issuance of long-term debt				$ 300,000,000
Interest rate, percent	3.60%				3.60%
Senior Debentures [Member] \| 3.5% senior debentures due 2049 [Member] \| IPL [Member]
Debt [Line Items]
Proceeds from issuance of long-term debt	$ 300,000,000
Interest rate, percent	3.50%				3.50%
Debentures [Member] \| 3% debentures due 2029 [Member] \| WPL [Member]
Debt [Line Items]
Proceeds from issuance of long-term debt			$ 350,000,000
Interest rate, percent	3.00%				3.00%
Debentures [Member] \| 5% debentures due 2019 [Member] \| WPL [Member]
Debt [Line Items]
Interest rate, percent			5.00%
Payments to retire long-term debt		$ 250,000,000
Parent Company [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	$ 450,000,000				$ 450,000,000