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Leases - Summary of Balance Sheet and Weighted-Average Information about Operating Leases (Details) $ in Millions | Sep. 30, 2020 USD ($)
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Lessee Lease Description [Line Items] |
Right-of-use assets | $ 65.1
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List] | us-gaap:OtherAssetsNoncurrent
Lease liabilities, current | $ 6.5
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] | us-gaap:OtherLiabilitiesCurrent
Lease liabilities, noncurrent | $ 58.4
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] | us-gaap:OtherLiabilitiesNoncurrent
Weighted-average remaining lease term | 15 years 10 months 24 days
Weighted-average discount rate | 4.20%
Spire Missouri Inc |
Lessee Lease Description [Line Items] |
Right-of-use assets | $ 1.7
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List] | us-gaap:OtherAssetsNoncurrent
Lease liabilities, current | $ 0.3
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] | us-gaap:OtherLiabilitiesCurrent
Lease liabilities, noncurrent | $ 1.4
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] | us-gaap:OtherLiabilitiesNoncurrent
Weighted-average remaining lease term | 5 years 3 months 18 days
Weighted-average discount rate | 2.50%
Spire Alabama |
Lessee Lease Description [Line Items] |
Right-of-use assets | $ 6.7
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List] | us-gaap:OtherAssetsNoncurrent
Lease liabilities, current | $ 1.9
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] | us-gaap:OtherLiabilitiesCurrent
Lease liabilities, noncurrent | $ 4.7
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] | us-gaap:OtherLiabilitiesNoncurrent
Weighted-average remaining lease term | 3 years 3 months 18 days
Weighted-average discount rate | 2.20%

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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 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 Amount of lessee's right to use underlying asset under 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 (a) -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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