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FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Millions | Sep. 30, 2017 | Sep. 30, 2016
--- | --- | ---
ASSETS |  |
Derivative asset after the effects of netting | $ 6.2 | $ 13.3
LIABILITIES |  |
Derivative liability after the effects of netting | 8.0 | 4.9
Spire Missouri |  |
ASSETS |  |
Derivative asset after the effects of netting | 0.1 | 4.9
LIABILITIES |  |
Derivative liability after the effects of netting | 0.0 | 0.2
Fair Value, Measurements, Recurring |  |
ASSETS |  |
Effects of netting and cash margin receivables/payables | (6.7) | (5.0)
Derivative asset after the effects of netting | 28.7 | 34.3
LIABILITIES |  |
Effects of netting and cash margin receivables/payables | (5.2) |
Derivative liability after the effects of netting | 8.1 |
Fair Value, Measurements, Recurring | Spire Missouri |  |
ASSETS |  |
Effects of netting and cash margin receivables/payables | (3.4) | (0.7)
Derivative asset after the effects of netting | 22.5 | 25.8
LIABILITIES |  |
Effects of netting and cash margin receivables/payables | (1.9) | (1.6)
Derivative liability after the effects of netting | 0.0 | 0.2
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1) |  |
ASSETS |  |
Derivative asset before effects of netting | 23.1 | 22.9
LIABILITIES |  |
Derivative liability before effects of netting | 3.7 |
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1) | Spire Missouri |  |
ASSETS |  |
Derivative asset before effects of netting | 21.8 | 22.4
LIABILITIES |  |
Derivative liability before effects of netting | 1.9 | 1.6
Fair Value, Measurements, Recurring | Significant Observable Inputs (Level 2) |  |
ASSETS |  |
Derivative asset before effects of netting | 12.2 | 16.2
LIABILITIES |  |
Derivative liability before effects of netting | 9.6 |
Fair Value, Measurements, Recurring | Significant Observable Inputs (Level 2) | Spire Missouri |  |
ASSETS |  |
Derivative asset before effects of netting | 4.1 | 4.1
LIABILITIES |  |
Derivative liability before effects of netting | 0.0 | 0.2
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) |  |
ASSETS |  |
Derivative asset before effects of netting | 0.1 | 0.2
LIABILITIES |  |
Derivative liability before effects of netting | 0.0 |
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Spire Missouri |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 | 0.0
LIABILITIES |  |
Derivative liability before effects of netting | 0.0 | 0.0
Fair Value, Measurements, Recurring | US stock/bond mutual funds | Spire Missouri |  |
ASSETS |  |
Effects of netting and cash margin receivables/payables | 0.0 | 0.0
Derivative asset after the effects of netting | 22.4 | 20.9
Fair Value, Measurements, Recurring | US stock/bond mutual funds | Quoted Prices in Active Markets (Level 1) | Spire Missouri |  |
ASSETS |  |
Derivative asset before effects of netting | 18.3 | 16.8
Fair Value, Measurements, Recurring | US stock/bond mutual funds | Significant Observable Inputs (Level 2) | Spire Missouri |  |
ASSETS |  |
Derivative asset before effects of netting | 4.1 | 4.1
Fair Value, Measurements, Recurring | US stock/bond mutual funds | Significant Unobservable Inputs (Level 3) | Spire Missouri |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 | 0.0
Fair Value, Measurements, Recurring | NYMEX/ICE natural gas contracts | Spire Missouri |  |
ASSETS |  |
Effects of netting and cash margin receivables/payables | (3.4) | (0.4)
Derivative asset after the effects of netting | 0.0 | 4.9
LIABILITIES |  |
Effects of netting and cash margin receivables/payables | (1.9) | (1.6)
Derivative liability after the effects of netting | 0.0 | 0.0
Fair Value, Measurements, Recurring | NYMEX/ICE natural gas contracts | Quoted Prices in Active Markets (Level 1) | Spire Missouri |  |
ASSETS |  |
Derivative asset before effects of netting | 3.4 | 5.3
LIABILITIES |  |
Derivative liability before effects of netting | 1.9 | 1.6
Fair Value, Measurements, Recurring | NYMEX/ICE natural gas contracts | Significant Observable Inputs (Level 2) | Spire Missouri |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 | 0.0
LIABILITIES |  |
Derivative liability before effects of netting | 0.0 | 0.0
Fair Value, Measurements, Recurring | NYMEX/ICE natural gas contracts | Significant Unobservable Inputs (Level 3) | Spire Missouri |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 | 0.0
LIABILITIES |  |
Derivative liability before effects of netting | 0.0 | 0.0
Fair Value, Measurements, Recurring | OTCBB natural gas contracts | Spire Missouri |  |
LIABILITIES |  |
Effects of netting and cash margin receivables/payables |  | 0.0
Derivative liability after the effects of netting |  | 0.2
Fair Value, Measurements, Recurring | OTCBB natural gas contracts | Quoted Prices in Active Markets (Level 1) | Spire Missouri |  |
LIABILITIES |  |
Derivative liability before effects of netting |  | 0.0
Fair Value, Measurements, Recurring | OTCBB natural gas contracts | Significant Observable Inputs (Level 2) | Spire Missouri |  |
LIABILITIES |  |
Derivative liability before effects of netting |  | 0.2
Fair Value, Measurements, Recurring | OTCBB natural gas contracts | Significant Unobservable Inputs (Level 3) | Spire Missouri |  |
LIABILITIES |  |
Derivative liability before effects of netting |  | 0.0
Fair Value, Measurements, Recurring | Gasoline and heating oil contracts | Spire Missouri |  |
ASSETS |  |
Effects of netting and cash margin receivables/payables | 0.0 | (0.3)
Derivative asset after the effects of netting | 0.1 | 0.0
Fair Value, Measurements, Recurring | Gasoline and heating oil contracts | Quoted Prices in Active Markets (Level 1) | Spire Missouri |  |
ASSETS |  |
Derivative asset before effects of netting | 0.1 | 0.3
Fair Value, Measurements, Recurring | Gasoline and heating oil contracts | Significant Observable Inputs (Level 2) | Spire Missouri |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 | 0.0
Fair Value, Measurements, Recurring | Gasoline and heating oil contracts | Significant Unobservable Inputs (Level 3) | Spire Missouri |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 | 0.0
Fair Value, Measurements, Recurring | Gas Utility: | Gasoline and heating oil contracts |  |
ASSETS |  |
Effects of netting and cash margin receivables/payables |  | (0.3)
Derivative asset after the effects of netting |  | 0.1
Fair Value, Measurements, Recurring | Gas Utility: | Gasoline and heating oil contracts | Quoted Prices in Active Markets (Level 1) |  |
ASSETS |  |
Derivative asset before effects of netting |  | 0.4
Fair Value, Measurements, Recurring | Gas Utility: | Gasoline and heating oil contracts | Significant Observable Inputs (Level 2) |  |
ASSETS |  |
Derivative asset before effects of netting |  | 0.0
Fair Value, Measurements, Recurring | Gas Utility: | Gasoline and heating oil contracts | Significant Unobservable Inputs (Level 3) |  |
ASSETS |  |
Derivative asset before effects of netting |  | 0.0
Fair Value, Measurements, Recurring | Gas Marketing: |  |
LIABILITIES |  |
Effects of netting and cash margin receivables/payables |  | 7.6
Derivative liability after the effects of netting |  | 4.9
Fair Value, Measurements, Recurring | Gas Marketing: | Quoted Prices in Active Markets (Level 1) |  |
LIABILITIES |  |
Derivative liability before effects of netting |  | 5.1
Fair Value, Measurements, Recurring | Gas Marketing: | Significant Observable Inputs (Level 2) |  |
LIABILITIES |  |
Derivative liability before effects of netting |  | 7.4
Fair Value, Measurements, Recurring | Gas Marketing: | Significant Unobservable Inputs (Level 3) |  |
LIABILITIES |  |
Derivative liability before effects of netting |  | 0.0
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | US stock/bond mutual funds |  |
ASSETS |  |
Effects of netting and cash margin receivables/payables | 0.0 | 0.0
Derivative asset after the effects of netting | 22.4 | 20.9
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | US stock/bond mutual funds | Quoted Prices in Active Markets (Level 1) |  |
ASSETS |  |
Derivative asset before effects of netting | 18.3 | 16.8
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | US stock/bond mutual funds | Significant Observable Inputs (Level 2) |  |
ASSETS |  |
Derivative asset before effects of netting | 4.1 | 4.1
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | US stock/bond mutual funds | Significant Unobservable Inputs (Level 3) |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 | 0.0
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | NYMEX/ICE natural gas contracts |  |
ASSETS |  |
Effects of netting and cash margin receivables/payables | (3.4) | (0.4)
Derivative asset after the effects of netting | 0.0 | 4.9
LIABILITIES |  |
Effects of netting and cash margin receivables/payables | (1.9) | (1.6)
Derivative liability after the effects of netting | 0.0 | 0.0
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | NYMEX/ICE natural gas contracts | Quoted Prices in Active Markets (Level 1) |  |
ASSETS |  |
Derivative asset before effects of netting | 3.4 | 5.3
LIABILITIES |  |
Derivative liability before effects of netting | 1.9 | 1.6
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | NYMEX/ICE natural gas contracts | Significant Observable Inputs (Level 2) |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 | 0.0
LIABILITIES |  |
Derivative liability before effects of netting | 0.0 | 0.0
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | NYMEX/ICE natural gas contracts | Significant Unobservable Inputs (Level 3) |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 | 0.0
LIABILITIES |  |
Derivative liability before effects of netting | 0.0 | 0.0
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | OTCBB natural gas contracts |  |
LIABILITIES |  |
Effects of netting and cash margin receivables/payables |  | 0.0
Derivative liability after the effects of netting |  | 0.2
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | OTCBB natural gas contracts | Quoted Prices in Active Markets (Level 1) |  |
LIABILITIES |  |
Derivative liability before effects of netting |  | 0.0
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | OTCBB natural gas contracts | Significant Observable Inputs (Level 2) |  |
LIABILITIES |  |
Derivative liability before effects of netting |  | 0.2
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | OTCBB natural gas contracts | Significant Unobservable Inputs (Level 3) |  |
LIABILITIES |  |
Derivative liability before effects of netting |  | 0.0
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | Gasoline and heating oil contracts |  |
ASSETS |  |
Effects of netting and cash margin receivables/payables | 0.0 |
Derivative asset after the effects of netting | 0.1 |
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | Gasoline and heating oil contracts | Quoted Prices in Active Markets (Level 1) |  |
ASSETS |  |
Derivative asset before effects of netting | 0.1 |
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | Gasoline and heating oil contracts | Significant Observable Inputs (Level 2) |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 |
Operating Segments | Fair Value, Measurements, Recurring | Gas Utility: | Gasoline and heating oil contracts | Significant Unobservable Inputs (Level 3) |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 |
Operating Segments | Fair Value, Measurements, Recurring | Gas Marketing: | NYMEX/ICE natural gas contracts |  |
ASSETS |  |
Effects of netting and cash margin receivables/payables | (2.1) |
Derivative asset after the effects of netting | 0.5 |
LIABILITIES |  |
Effects of netting and cash margin receivables/payables | (2.1) | (5.1)
Derivative liability after the effects of netting | 0.0 | 0.0
Operating Segments | Fair Value, Measurements, Recurring | Gas Marketing: | NYMEX/ICE natural gas contracts | Quoted Prices in Active Markets (Level 1) |  |
ASSETS |  |
Derivative asset before effects of netting | 1.3 |
LIABILITIES |  |
Derivative liability before effects of netting | 1.8 | 3.5
Operating Segments | Fair Value, Measurements, Recurring | Gas Marketing: | NYMEX/ICE natural gas contracts | Significant Observable Inputs (Level 2) |  |
ASSETS |  |
Derivative asset before effects of netting | 1.3 |
LIABILITIES |  |
Derivative liability before effects of netting | 0.3 | 1.6
Operating Segments | Fair Value, Measurements, Recurring | Gas Marketing: | NYMEX/ICE natural gas contracts | Significant Unobservable Inputs (Level 3) |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 |
LIABILITIES |  |
Derivative liability before effects of netting | 0.0 | 0.0
Operating Segments | Fair Value, Measurements, Recurring | Gas Marketing: | NYMEX/ICE natural gas contracts |  |
ASSETS |  |
Effects of netting and cash margin receivables/payables |  | (3.4)
Derivative asset after the effects of netting |  | 0.4
Operating Segments | Fair Value, Measurements, Recurring | Gas Marketing: | NYMEX/ICE natural gas contracts | Quoted Prices in Active Markets (Level 1) |  |
ASSETS |  |
Derivative asset before effects of netting |  | 0.4
Operating Segments | Fair Value, Measurements, Recurring | Gas Marketing: | NYMEX/ICE natural gas contracts | Significant Observable Inputs (Level 2) |  |
ASSETS |  |
Derivative asset before effects of netting |  | 3.4
Operating Segments | Fair Value, Measurements, Recurring | Gas Marketing: | NYMEX/ICE natural gas contracts | Significant Unobservable Inputs (Level 3) |  |
ASSETS |  |
Derivative asset before effects of netting |  | 0.0
Operating Segments | Fair Value, Measurements, Recurring | Gas Marketing: | Natural gas commodity contracts |  |
ASSETS |  |
Effects of netting and cash margin receivables/payables | (1.2) | (0.9)
Derivative asset after the effects of netting | 5.7 | 8.0
LIABILITIES |  |
Effects of netting and cash margin receivables/payables | (1.2) | (0.9)
Derivative liability after the effects of netting | 7.2 | 1.7
Operating Segments | Fair Value, Measurements, Recurring | Gas Marketing: | Natural gas commodity contracts | Quoted Prices in Active Markets (Level 1) |  |
ASSETS |  |
Derivative asset before effects of netting | 0.0 | 0.0
LIABILITIES |  |
Derivative liability before effects of netting | 0.0 | 0.0
Operating Segments | Fair Value, Measurements, Recurring | Gas Marketing: | Natural gas commodity contracts | Significant Observable Inputs (Level 2) |  |
ASSETS |  |
Derivative asset before effects of netting | 6.8 | 8.7
LIABILITIES |  |
Derivative liability before effects of netting | 8.4 | 2.6
Operating Segments | Fair Value, Measurements, Recurring | Gas Marketing: | Natural gas commodity contracts | Significant Unobservable Inputs (Level 3) |  |
ASSETS |  |
Derivative asset before effects of netting | 0.1 | 0.2
LIABILITIES |  |
Derivative liability before effects of netting | 0.0 | 0.0
Other | Fair Value, Measurements, Recurring | Interest rate swaps |  |
LIABILITIES |  |
Effects of netting and cash margin receivables/payables | 0.0 | 0.0
Derivative liability after the effects of netting | 0.9 | 3.0
Other | Fair Value, Measurements, Recurring | Interest rate swaps | Quoted Prices in Active Markets (Level 1) |  |
LIABILITIES |  |
Derivative liability before effects of netting | 0.0 | 0.0
Other | Fair Value, Measurements, Recurring | Interest rate swaps | Significant Observable Inputs (Level 2) |  |
LIABILITIES |  |
Derivative liability before effects of netting | 0.9 | 3.0
Other | Fair Value, Measurements, Recurring | Interest rate swaps | Significant Unobservable Inputs (Level 3) |  |
LIABILITIES |  |
Derivative liability before effects of netting | $ 0.0 | $ 0.0

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