Amortization Of Regulatory Assets For Which No Return On Investment During Recovery Period Is Provided

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- Definition

Anticipated contributions to the pension plans for fiscal year 2012 for non-qualified plans.

+ References

No definition available.

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- Definition

Anticipated contributions to the pension plans for the next fiscal year for qualified trusts.

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No definition available.

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- Definition

Anticipated contribution to the postretirement plans for the next fiscal year for qualified trusts.

+ References

No definition available.

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- Definition

Anticipated payment to the postretirement plans participants for the next fiscal year for non-qualified trusts.

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No definition available.

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- Definition

Reflects the upper limit on age eligibility, post early retirement, when medical insurance is available to retiree.

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No definition available.

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- Definition

Gains and losses not yet includible in pension/postretirement benefit cost are amortized only to the extent that such gain or loss exceeds 10% of the greater of the benefit obligation or the market-related value of plan assets

+ References

No definition available.

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- Definition

Disclosure under Missouri Public Service Commission Order, the return on plan assets if based on the market-related value of plan assets implemented prospectively over a four-year period.

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No definition available.

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-- None. No documentation exists for this element. --

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No definition available.

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- Definition

The amount of annual recovery of postretirement benefit costs allowed in rates by the Missouri Public Service Commission. The differences between these amounts and those calculated pursuant to GAAP are deferred as regulatory assets or liabilities.

+ References

No definition available.

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- Definition

The amount of annual recovery of net pension costs allowed in rates for qualified pension plans by the Missouri Public Service Commission. The differences between these amounts and those calculated pursuant to GAAP are deferred as regulatory assets or liabilities.

+ References

No definition available.

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- Definition

Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

+ References

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- Definition

Amount of (increase) decrease to benefit obligation of defined benefit plan from remeasurement due to settlement. Excludes decrease to benefit obligation for settlement payment.

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- Definition

Amount of contribution received by defined benefit plan from employer which increases plan assets.

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of cost for defined contribution plan.

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- Definition

The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

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- Definition

Remaining recovery period of regulatory assets for which no return on investment during recovery period is provided, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS - Narrative (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Apr. 19, 2018	Mar. 07, 2018	Apr. 11, 2017	Jan. 01, 2011	Feb. 20, 2010
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Settlement benefits paid			$ 62.2
Implementation period used to calculate return on plan assets		4 years
Gains or losses includible in cost amortized to extent exceeds benefit obligations or market-related value of plan assets, percentage		10.00%
Regulatory assets		$ 742.6	966.6
Remaining recovery period for regulatory assets for which no return on investment during recovery period is provided		15 years
Anticipated Contributions to pension plans for qualified trust		$ 27.1
Anticipated contributions to pension plans for non-qualified plans		$ 0.5
Medical insurance available until age is reached after early retirement		65 years
Recovery in rates for postretirement benefit								$ 9.5
Other Plans [Abstract]
401(K) plans, cost of defined contributions		$ 0.0	0.0	$ 0.0
Spire Missouri
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Recovery in rates for the qualified pension plans base allowance								$ 15.5
Regulatory assets		471.8	653.4
Other Plans [Abstract]
401(K) plans, cost of defined contributions		9.0	8.4	8.2
Spire Alabama
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Regulatory assets		227.7	261.6
Other Plans [Abstract]
401(K) plans, cost of defined contributions		3.0	2.7	2.3
Spire Missouri West
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Recovery in rates for the qualified pension plans base allowance									$ 9.9
Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Settlement benefits paid		82.8	62.2
Employer contributions		58.9	$ 41.3
Pension Plans \| Spire Missouri
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rates	4.20%		3.70%
Settlement benefits paid		65.5	$ 43.5
Employer contributions		$ 36.9	$ 29.4
Targeted allocation of plan assets		100.00%	100.00%
Pension Plans \| Spire Alabama
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rates		4.20%	3.65%
Settlement benefits paid		$ 17.3	$ 18.7	$ 16.6
Employer contributions		$ 20.1	$ 11.9
Targeted allocation of plan assets		100.00%	100.00%
Other Pension Plan \| Spire Missouri
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rates	4.15%		3.75%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions		$ 7.6	$ 10.4
Anticipated contributions to the postretirement plans for qualified trusts		1.9
Anticipated payment directly to participants in postretirement plan		$ 0.5
Other Postretirement Benefits Plan [Member] \| Spire Missouri
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rates		3.00%	3.00%
Employer contributions		$ 7.6	$ 10.4
Targeted allocation of plan assets		100.00%
Other Postretirement Benefits Plan [Member] \| Spire Alabama
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions		$ 0.0	$ 0.0
Targeted allocation of plan assets		100.00%
Equity markets \| Pension Plans \| Spire Missouri
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Targeted allocation of plan assets		56.40%	56.40%
Equity markets \| Pension Plans \| Spire Alabama
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Targeted allocation of plan assets		60.00%	60.00%
Equity markets \| Other Postretirement Benefits Plan [Member] \| Spire Missouri
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Targeted allocation of plan assets		60.00%
Equity markets \| Other Postretirement Benefits Plan [Member] \| Spire Alabama
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Targeted allocation of plan assets		60.00%
Debt securities \| Pension Plans \| Spire Missouri
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Targeted allocation of plan assets		43.60%	43.60%
Debt securities \| Pension Plans \| Spire Alabama
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Targeted allocation of plan assets		29.00%	29.00%
Debt securities \| Other Postretirement Benefits Plan [Member] \| Spire Missouri
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Targeted allocation of plan assets		40.00%
Debt securities \| Other Postretirement Benefits Plan [Member] \| Spire Alabama
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Targeted allocation of plan assets		40.00%
Pension Cost \| MoPSC \| Infrastructure System Replacement Surcharge \| Spire Missouri West
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Regulatory assets						$ 5.5	$ 9.9
Pension Cost \| MoPSC \| Infrastructure System Replacement Surcharge \| Spire Missouri East
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Regulatory assets						29.0	15.5
Pension and Other Postretirement Benefits \| Spire Missouri West
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Amortization of assets	$ 26.2	$ 26.2
Pension and Other Postretirement Benefits \| Spire Missouri East
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Remaining recovery period for regulatory assets for which no return on investment during recovery period is provided	8 years	8 years
Amortization of assets	$ 173.0	$ 173.0
Pension and Other Postretirement Benefits \| Spire Alabama
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions		$ 20.1	$ 11.9
Postretirement Benefit Costs \| MoPSC \| Infrastructure System Replacement Surcharge \| Spire Missouri East
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Regulatory assets					$ 8.6	$ 8.6	$ 9.5