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INCOME TAXES - Significant Items in Net Deferred Tax Liability (Details) - USD ($) $ in Millions | Sep. 30, 2017 | Sep. 30, 2016
--- | --- | ---
Deferred tax assets: |  |
Reserves not currently deductible | $ 31.5 | $ 21.3
Pension and other postretirement benefits | 58.6 | 68.3
Operating losses | 169.6 | 102.3
Other | 26.0 | 0.0
Deferred tax assets | 285.7 | 191.9
Less: valuation allowance | 0.5 | 0.9
Total deferred tax assets | 285.2 | 191.0
Deferred tax liabilities: |  |
Relating to property | 728.3 | 623.1
Regulatory pension and other postretirement benefits | 108.0 | 106.8
Deferred gas costs | 30.6 | 20.0
Other | 125.8 | 48.4
Total deferred tax liabilities | 992.7 | 798.3
Net deferred tax liability | 707.5 | 607.3
Spire Missouri |  |
Deferred tax assets: |  |
Reserves not currently deductible |  | 14.9
Pension and other postretirement benefits |  | 56.9
Operating losses |  | 29.9
Deferred tax assets | 130.0 | 101.7
Less: valuation allowance | 0.5 | 0.9
Total deferred tax assets | 129.5 | 100.8
Deferred tax liabilities: |  |
Relating to property |  | 497.0
Regulatory pension and other postretirement benefits |  | 106.8
Deferred gas costs |  | 20.0
Other |  | 33.9
Total deferred tax liabilities | 753.3 | 657.7
Net deferred tax liability | 623.8 | 556.9
Spire Alabama |  |
Deferred tax assets: |  |
Reserves not currently deductible | 6.0 | 6.3
Pension and other postretirement benefits | 4.4 | 11.4
Goodwill | 214.4 | 233.4
Operating losses | 88.3 | 60.2
Deferred tax assets | 313.1 | 311.3
Deferred tax liabilities: |  |
Relating to property | 119.3 | 87.6
Other | 8.2 | 2.3
Total deferred tax liabilities | 127.5 | 89.9
Net deferred tax asset | $ 185.6 | $ 221.4

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