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PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS - Narrative (Details) | 3 Months Ended
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Dec. 31, 2017 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |
Medical insurance available until age is reached after early retirement | 65 years
Pension Plans | Spire Alabama |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |
Contributions made by employer | $ 0
Pension Plans | Spire Missouri |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |
Contributions made by employer | 6,500,000
Anticipated contributions to pension plans for qualified trust | 29,400,000
Nonqualified Pension Plans | Spire Missouri |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |
Contributions made by employer | 0
Anticipated contributions to pension plans for qualified trust | 500,000
Postretirement Plans |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |
Anticipated contributions to pension plans for qualified trust | 6,900,000
Anticipated payment directly to participants in postretirement plan | $ 800,000

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- Definition Anticipated payment to the postretirement plans participants for the next fiscal year for non-qualified trusts. + References No definition available. + Details
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- Definition Reflects the upper limit on age eligibility, post early retirement, when medical insurance is available to retiree. + References No definition available. + Details
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- Definition Amount of contribution received by defined benefit plan from employer which increases plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(5)(ii) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2709-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(5)(iv)(01) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of contributions expected to be received by defined benefit plan from employer in fiscal year. Excludes contributions paid by employer in current fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2709-114920 + Details
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