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Leases (Operating Leases) (Details) - USD ($) $ in Millions | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Leases [Line Items] |  |
Operating leases assets, Property, plant and equipment, net | $ 15 | $ 16
Operating leases liabilities, Other current liabilities | 2 | 2
Operating leases liabilities, Other liabilities | 13 | 14
Operating leases liabilities, Total | $ 15 | $ 16
Operating leases, Weighted average remaining lease term | 10 years | 11 years
Operating leases, Weighted average discount rate, percent | 4.00% | 4.00%
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] | us-gaap:OtherLiabilitiesCurrent | us-gaap:OtherLiabilitiesCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] | us-gaap:OtherLiabilitiesNoncurrent | us-gaap:OtherLiabilitiesNoncurrent
IPL [Member] |  |
Leases [Line Items] |  |
Operating leases assets, Property, plant and equipment, net | $ 9 | $ 10
Operating leases liabilities, Other current liabilities | 1 | 1
Operating leases liabilities, Other liabilities | 8 | 9
Operating leases liabilities, Total | $ 9 | $ 10
Operating leases, Weighted average remaining lease term | 11 years | 12 years
Operating leases, Weighted average discount rate, percent | 4.00% | 4.00%
WPL [Member] |  |
Leases [Line Items] |  |
Operating leases assets, Property, plant and equipment, net | $ 6 | $ 6
Operating leases liabilities, Other current liabilities | 1 | 1
Operating leases liabilities, Other liabilities | 5 | 5
Operating leases liabilities, Total | $ 6 | $ 6
Operating leases, Weighted average remaining lease term | 9 years | 10 years
Operating leases, Weighted average discount rate, percent | 4.00% | 4.00%

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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. + Details
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- Definition Discount rate used by lessee to determine present value of operating lease payments. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980 + Details
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- Definition Present value of lessee's discounted obligation for lease payments from operating lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918627-209977 + Details
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- Definition Present value of lessee's discounted obligation for lease payments from operating lease, classified as current. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918627-209977 + Details
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- Definition Present value of lessee's discounted obligation for lease payments from operating lease, classified as noncurrent. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121603541&loc=SL77918627-209977 + Details
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- Definition Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(3) -URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980 + Details
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