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Debt (Credit Facilities) (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
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Commercial paper and borrowings under the single credit facility: |  |
Amount outstanding | $ 515 | $ 389
Weighted average interest rates | 0.20% | 0.20%
Available credit facility capacity | $ 485 | $ 611
IPL [Member] |  |
Commercial paper and borrowings under the single credit facility: |  |
Amount outstanding | 0 | 0
Available credit facility capacity | 250 | 250
WPL [Member] |  |
Commercial paper and borrowings under the single credit facility: |  |
Amount outstanding | $ 236 | $ 257
Weighted average interest rates | 0.20% | 0.10%
Available credit facility capacity | $ 64 | $ 43

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- Definition Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)(2)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 3: 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)(a)(3)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Weighted average interest rate of short-term debt outstanding calculated at point in time. + 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)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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