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FAIR VALUE MEASUREMENTS (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions | Dec. 31, 2017 | Sep. 30, 2017 | Dec. 31, 2016
--- | --- | --- | ---
LIABILITIES |  |  |
Effects of Netting and Cash Margin Receivables /Payables | $ (14.0) |  |
Derivative liability | 5.8 |  |
Spire Missouri |  |  |
ASSETS |  |  |
Effects of Netting and Cash Margin Receivables /Payables | (0.5) | $ (3.4) | $ (6.6)
Derivative asset | 23.5 | 22.5 | 23.9
LIABILITIES |  |  |
Effects of Netting and Cash Margin Receivables /Payables | (2.7) | (1.9) | (0.2)
Derivative liability | 0.0 | 0.0 | 0.0
Quoted Prices in Active Markets (Level 1) |  |  |
LIABILITIES |  |  |
Derivative liability before netting adjustment | 3.8 |  |
Quoted Prices in Active Markets (Level 1) | Spire Missouri |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 20.0 | 21.8 | 26.5
LIABILITIES |  |  |
Derivative liability before netting adjustment | 2.7 | 1.9 | 0.2
Significant Observable Inputs (Level 2) |  |  |
LIABILITIES |  |  |
Derivative liability before netting adjustment | 15.6 |  |
Significant Observable Inputs (Level 2) | Spire Missouri |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 4.0 | 4.1 | 4.0
LIABILITIES |  |  |
Derivative liability before netting adjustment | 0.0 | 0.0 | 0.0
Significant Unobservable Inputs (Level 3) |  |  |
LIABILITIES |  |  |
Derivative liability before netting adjustment | 0.4 |  |
Significant Unobservable Inputs (Level 3) | Spire Missouri |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.0 | 0.0 | 0.0
LIABILITIES |  |  |
Derivative liability before netting adjustment | 0.0 | 0.0 | 0.0
US stock/bond mutual funds | Spire Missouri |  |  |
ASSETS |  |  |
Effects of Netting and Cash Margin Receivables /Payables | 0.0 | 0.0 | 0.0
Derivative asset | 23.5 | 22.4 | 21.2
US stock/bond mutual funds | Quoted Prices in Active Markets (Level 1) | Spire Missouri |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 19.5 | 18.3 | 17.2
US stock/bond mutual funds | Significant Observable Inputs (Level 2) | Spire Missouri |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 4.0 | 4.1 | 4.0
US stock/bond mutual funds | Significant Unobservable Inputs (Level 3) | Spire Missouri |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.0 | 0.0 | 0.0
NYMEX/ICE natural gas contracts |  |  |
LIABILITIES |  |  |
Effects of Netting and Cash Margin Receivables /Payables |  |  | (0.2)
Derivative liability |  |  | 0.0
NYMEX/ICE natural gas contracts | Spire Missouri |  |  |
ASSETS |  |  |
Effects of Netting and Cash Margin Receivables /Payables | (0.5) | (3.4) | (6.6)
Derivative asset | 0.0 | 0.0 | 2.2
LIABILITIES |  |  |
Effects of Netting and Cash Margin Receivables /Payables | (2.7) | (1.9) |
Derivative liability | 0.0 | 0.0 |
NYMEX/ICE natural gas contracts | Quoted Prices in Active Markets (Level 1) |  |  |
LIABILITIES |  |  |
Derivative liability before netting adjustment |  |  | 0.2
NYMEX/ICE natural gas contracts | Quoted Prices in Active Markets (Level 1) | Spire Missouri |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.5 | 3.4 | 8.8
LIABILITIES |  |  |
Derivative liability before netting adjustment | 2.7 | 1.9 |
NYMEX/ICE natural gas contracts | Significant Observable Inputs (Level 2) |  |  |
LIABILITIES |  |  |
Derivative liability before netting adjustment |  |  | 0.0
NYMEX/ICE natural gas contracts | Significant Observable Inputs (Level 2) | Spire Missouri |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.0 | 0.0 | 0.0
LIABILITIES |  |  |
Derivative liability before netting adjustment | 0.0 | 0.0 |
NYMEX/ICE natural gas contracts | Significant Unobservable Inputs (Level 3) |  |  |
LIABILITIES |  |  |
Derivative liability before netting adjustment |  |  | 0.0
NYMEX/ICE natural gas contracts | Significant Unobservable Inputs (Level 3) | Spire Missouri |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.0 | 0.0 | 0.0
LIABILITIES |  |  |
Derivative liability before netting adjustment | 0.0 | 0.0 |
Gasoline and heating oil contracts | Spire Missouri |  |  |
ASSETS |  |  |
Effects of Netting and Cash Margin Receivables /Payables |  | 0.0 | 0.0
Derivative asset |  | 0.1 | 0.5
Gasoline and heating oil contracts | Quoted Prices in Active Markets (Level 1) | Spire Missouri |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment |  | 0.1 | 0.5
Gasoline and heating oil contracts | Significant Observable Inputs (Level 2) | Spire Missouri |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment |  | 0.0 | 0.0
Gasoline and heating oil contracts | Significant Unobservable Inputs (Level 3) | Spire Missouri |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment |  | 0.0 | 0.0
Other | Interest rate swaps |  |  |
LIABILITIES |  |  |
Effects of Netting and Cash Margin Receivables /Payables | 0.0 | 0.0 |
Derivative liability | 0.8 | 0.9 |
Other | Interest rate swaps | Quoted Prices in Active Markets (Level 1) |  |  |
LIABILITIES |  |  |
Derivative liability before netting adjustment | 0.0 | 0.0 |
Other | Interest rate swaps | Significant Observable Inputs (Level 2) |  |  |
LIABILITIES |  |  |
Derivative liability before netting adjustment | 0.8 | 0.9 |
Other | Interest rate swaps | Significant Unobservable Inputs (Level 3) |  |  |
LIABILITIES |  |  |
Derivative liability before netting adjustment | 0.0 | 0.0 |
Gas Utility | US stock/bond mutual funds |  |  |
ASSETS |  |  |
Effects of Netting and Cash Margin Receivables /Payables | 0.0 | 0.0 | 0.0
Derivative asset | 23.5 | 22.4 | 21.2
Gas Utility | US stock/bond mutual funds | Quoted Prices in Active Markets (Level 1) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 19.5 | 18.3 | 17.2
Gas Utility | US stock/bond mutual funds | Significant Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 4.0 | 4.1 | 4.0
Gas Utility | US stock/bond mutual funds | Significant Unobservable Inputs (Level 3) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.0 | 0.0 | 0.0
Gas Utility | NYMEX/ICE natural gas contracts |  |  |
ASSETS |  |  |
Effects of Netting and Cash Margin Receivables /Payables | (0.5) | (3.4) | (6.6)
Derivative asset | 0.0 | 0.0 | 2.2
LIABILITIES |  |  |
Effects of Netting and Cash Margin Receivables /Payables | (2.7) | (1.9) | (0.2)
Derivative liability | 0.0 | 0.0 | 0.0
Gas Utility | NYMEX/ICE natural gas contracts | Quoted Prices in Active Markets (Level 1) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.5 | 3.4 | 8.8
LIABILITIES |  |  |
Derivative liability before netting adjustment | 2.7 | 1.9 | 0.2
Gas Utility | NYMEX/ICE natural gas contracts | Significant Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.0 | 0.0 | 0.0
LIABILITIES |  |  |
Derivative liability before netting adjustment | 0.0 | 0.0 | 0.0
Gas Utility | NYMEX/ICE natural gas contracts | Significant Unobservable Inputs (Level 3) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.0 | 0.0 | 0.0
LIABILITIES |  |  |
Derivative liability before netting adjustment | 0.0 | 0.0 | 0.0
Gas Utility | Gasoline and heating oil contracts |  |  |
ASSETS |  |  |
Effects of Netting and Cash Margin Receivables /Payables |  | 0.0 | 0.0
Derivative asset |  | 0.1 | 0.7
Gas Utility | Gasoline and heating oil contracts | Quoted Prices in Active Markets (Level 1) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment |  | 0.1 | 0.7
Gas Utility | Gasoline and heating oil contracts | Significant Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment |  | 0.0 | 0.0
Gas Utility | Gasoline and heating oil contracts | Significant Unobservable Inputs (Level 3) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment |  | 0.0 | 0.0
Gas Marketing |  |  |
ASSETS |  |  |
Effects of Netting and Cash Margin Receivables /Payables | (10.9) | (6.7) |
Derivative asset | 27.2 | 28.7 |
LIABILITIES |  |  |
Effects of Netting and Cash Margin Receivables /Payables |  | (5.2) | (10.4)
Derivative liability |  | 8.1 | 3.5
Gas Marketing | Quoted Prices in Active Markets (Level 1) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 22.4 | 23.1 |
LIABILITIES |  |  |
Derivative liability before netting adjustment |  | 3.7 | 5.3
Gas Marketing | Significant Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 15.7 | 12.2 |
LIABILITIES |  |  |
Derivative liability before netting adjustment |  | 9.6 | 8.6
Gas Marketing | Significant Unobservable Inputs (Level 3) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.0 | 0.1 |
LIABILITIES |  |  |
Derivative liability before netting adjustment |  | 0.0 | 0.0
Gas Marketing | US stock/bond mutual funds |  |  |
ASSETS |  |  |
Effects of Netting and Cash Margin Receivables /Payables |  |  | (11.8)
Derivative asset |  |  | 42.1
Gas Marketing | US stock/bond mutual funds | Quoted Prices in Active Markets (Level 1) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment |  |  | 27.4
Gas Marketing | US stock/bond mutual funds | Significant Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment |  |  | 26.5
Gas Marketing | US stock/bond mutual funds | Significant Unobservable Inputs (Level 3) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment |  |  | 0.0
Gas Marketing | NYMEX/ICE natural gas contracts |  |  |
ASSETS |  |  |
Effects of Netting and Cash Margin Receivables /Payables | (6.1) | (2.1) | (4.9)
Derivative asset | 0.3 | 0.5 | 0.3
LIABILITIES |  |  |
Effects of Netting and Cash Margin Receivables /Payables | (7.0) | (2.1) | (9.9)
Derivative liability | 0.0 | 0.0 | 0.0
Gas Marketing | NYMEX/ICE natural gas contracts | Quoted Prices in Active Markets (Level 1) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 2.4 | 1.3 | 0.7
LIABILITIES |  |  |
Derivative liability before netting adjustment | 1.1 | 1.8 | 5.1
Gas Marketing | NYMEX/ICE natural gas contracts | Significant Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 4.0 | 1.3 | 4.5
LIABILITIES |  |  |
Derivative liability before netting adjustment | 5.9 | 0.3 | 4.8
Gas Marketing | NYMEX/ICE natural gas contracts | Significant Unobservable Inputs (Level 3) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.0 | 0.0 | 0.0
LIABILITIES |  |  |
Derivative liability before netting adjustment | 0.0 | 0.0 | 0.0
Gas Marketing | Natural gas commodity contracts |  |  |
ASSETS |  |  |
Effects of Netting and Cash Margin Receivables /Payables | (4.3) | (1.2) | (0.3)
Derivative asset | 3.4 | 5.7 | 9.5
LIABILITIES |  |  |
Effects of Netting and Cash Margin Receivables /Payables | (4.3) | (1.2) | (0.3)
Derivative liability | 5.0 | 7.2 | 3.5
Gas Marketing | Natural gas commodity contracts | Quoted Prices in Active Markets (Level 1) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.0 | 0.0 | 0.0
LIABILITIES |  |  |
Derivative liability before netting adjustment | 0.0 | 0.0 | 0.0
Gas Marketing | Natural gas commodity contracts | Significant Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 7.7 | 6.8 | 9.8
LIABILITIES |  |  |
Derivative liability before netting adjustment | 8.9 | 8.4 | 3.8
Gas Marketing | Natural gas commodity contracts | Significant Unobservable Inputs (Level 3) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment | 0.0 | 0.1 | 0.0
LIABILITIES |  |  |
Derivative liability before netting adjustment | $ 0.4 | $ 0.0 | 0.0
Gas Marketing | Other |  |  |
ASSETS |  |  |
Effects of Netting and Cash Margin Receivables /Payables |  |  | 0.0
Derivative asset |  |  | 8.2
Gas Marketing | Other | Quoted Prices in Active Markets (Level 1) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment |  |  | 0.0
Gas Marketing | Other | Significant Observable Inputs (Level 2) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment |  |  | 8.2
Gas Marketing | Other | Significant Unobservable Inputs (Level 3) |  |  |
ASSETS |  |  |
Derivative asset before netting adjustment |  |  | $ 0.0

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