v3.26.1
Schedule of Assets (Held at End of Year) (Details) - EBP 009 - USD ($)
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
EBP, Schedule of Asset Held for Investment [Line Items]    
Entity Tax Identification Number 47-4582725  
EBP, Plan Number 009  
Current Value $ 760,079,577  
Notes receivable from participants 15,574,168  
Total Asset Held for Investment $ 775,653,745  
Investment, Identifier [Axis]: American Funds EuroPacific Growth Fund® - Class R6 | Mutual Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] American Funds EuroPacific Growth Fund [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 181,142.034  
Current Value $ 10,973,584  
Investment, Identifier [Axis]: BlackRock Equity Index M | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] BlackRock Equity Index M [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 1,941,508.023  
Current Value $ 122,411,304  
Investment, Identifier [Axis]: BlackRock MSCI ACWI ex-US IMI Index Fund T | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] BlackRock MSCI ACWI ex-US IMI Index Fund T [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 652,860.037  
Current Value $ 12,725,483  
Investment, Identifier [Axis]: BlackRock Money Market Fund W | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] BlackRock Money Market Fund W [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 22,742,612.51  
Current Value $ 22,742,613  
Investment, Identifier [Axis]: DFA Emerging Markets Core Equity Portfolio | Mutual Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] DFA Emerging Markets [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 159,277.049  
Current Value $ 4,631,777  
Investment, Identifier [Axis]: Delaware Small Cap Value Fund Class R6 |Mutual Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Delaware Small Cap Value Fund [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 82,404.02  
Current Value $ 5,534,254  
Investment, Identifier [Axis]: Fidelity Mid Cap Index Fund | Mutual Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Fidelity Mid Cap Index Fund [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 351,509.282  
Current Value $ 12,981,238  
EBP, Asset Held for Investment, Party-in-Interest [true false] true  
Investment, Identifier [Axis]: Fidelity Small Cap Index Fund | Mutual Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Fidelity Small Cap Index Fund [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 1,106,480.04  
Current Value $ 34,223,428  
EBP, Asset Held for Investment, Party-in-Interest [true false] true  
Investment, Identifier [Axis]: Galliard Stable Return Fund C | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Galliard Stable Return Fund C [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 160,096.053  
Current Value $ 10,143,686  
Investment, Identifier [Axis]: JP Morgan Large Cap Growth Fund Class R6 | Mutual Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] JP Morgan Large Cap Growth Fund Class R6 [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 667,587.409  
Current Value $ 57,706,256  
Investment, Identifier [Axis]: Lord Abbett Total Return Trust II Class BP | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Lord Abbett Total Return Trust II Class BP [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 1,820,751.929  
Current Value $ 22,086,449  
Investment, Identifier [Axis]: PIMCO International Bond Fund | Mutual Fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] PIMCO International Bond Fund [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Mutual Fund [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 221,034.933  
Current Value $ 2,194,877  
Investment, Identifier [Axis]: Principal Diversified Real Asset CIT Tier 1 | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Principal Diversified Real Asset CIT Tier 1 [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 104,058.083  
Current Value $ 1,667,010  
Investment, Identifier [Axis]: Self-Directed Brokerage Accounts | Common Stock, Exchange-Traded Funds (ETFs), Trusts, Mutual Funds    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] EBP, Self-Directed Brokerage Account [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Stock, Exchange-Traded Funds (ETFs), Trusts, Mutual Funds [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
Current Value $ 9,528,697  
Investment, Identifier [Axis]: Spire Inc. - ESOP | Company stock fund    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Spire Inc ESOP [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanEmployerCommonStockFundMember  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 663,069.598  
Current Value $ 54,835,856  
EBP, Asset Held for Investment, Party-in-Interest [true false] true  
Investment, Identifier [Axis]: Vanguard Institutional Target 2020 Fund | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Vanguard Institutional [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 140,489.879  
Current Value $ 7,392,577  
Investment, Identifier [Axis]: Vanguard Institutional Target 2025 Fund | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Vanguard Institutional [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 477,239.384  
Current Value $ 27,049,928  
Investment, Identifier [Axis]: Vanguard Institutional Target 20250 Fund | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Vanguard Institutional [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 697,567.43  
Current Value $ 52,212,922  
Investment, Identifier [Axis]: Vanguard Institutional Target 2030 Fund | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Vanguard Institutional [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 665,374.521  
Current Value $ 39,529,900  
Investment, Identifier [Axis]: Vanguard Institutional Target 2035 Fund | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Vanguard Institutional [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 856,675.71  
Current Value $ 54,381,774  
Investment, Identifier [Axis]: Vanguard Institutional Target 2040 Fund | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Vanguard Institutional [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 845,308.472  
Current Value $ 58,123,411  
Investment, Identifier [Axis]: Vanguard Institutional Target 2045 Fund | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Vanguard Institutional [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 851,547.462  
Current Value $ 61,762,737  
Investment, Identifier [Axis]: Vanguard Institutional Target 2055 Fund | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Vanguard Institutional [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 387,741.364  
Current Value $ 38,874,949  
Investment, Identifier [Axis]: Vanguard Institutional Target 2060 Fund | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Vanguard Institutional [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 309,345.179  
Current Value $ 24,481,577  
Investment, Identifier [Axis]: Vanguard Institutional Target 2065 Fund | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Vanguard Institutional [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 153,215.484  
Current Value $ 7,464,658  
Investment, Identifier [Axis]: Vanguard Institutional Target 2070 Fund | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Vanguard Institutional [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 32,176.656  
Current Value $ 956,290  
Investment, Identifier [Axis]: Vanguard Institutional Target Income Fund | Common / Collective Trust    
EBP, Schedule of Asset Held for Investment [Line Items]    
EBP, Investment, Issuer Name [Extensible Enumeration] Vanguard Institutional [Member]  
EBP, Investment, Current Value, Type [Extensible Enumeration] Common Collective Trust [Member]  
EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Participation Status [Extensible Enumeration] us-gaap-ebp:EmployeeBenefitPlanParticipantDirectedMember  
EBP, Investment, Number of Shares 69,094.808  
Current Value $ 3,462,341  
Minimum    
EBP, Schedule of Asset Held for Investment [Line Items]    
Employee benefit plan, participant loans interest rate 4.25% 4.25%
Maximum    
EBP, Schedule of Asset Held for Investment [Line Items]    
Employee benefit plan, participant loans interest rate 9.50% 9.50%