XML 99 R84.htm IDEA: XBRL DOCUMENT
v2.4.0.8

PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS - Narrative (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended |  |  |  |  |  | 12 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2012 | Jan. 01, 2011 | Aug. 01, 2007 | Jan. 01, 2011 Laclede Gas | Aug. 01, 2007 Laclede Gas | Feb. 20, 2010 Missouri Gas Energy (MGE) | Sep. 30, 2014 Pension Plans | Sep. 30, 2013 Pension Plans | Sep. 30, 2012 Pension Plans | Sep. 30, 2014 Postretirement Plans | Sep. 30, 2014 Postretirement Plans | Sep. 30, 2013 Postretirement Plans | Sep. 30, 2012 Postretirement Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Extent of Lump-sum payments recognized, percentage | 100.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lump-sum payments recognized as settlements | $ 22.1 | $ 79.5 |  |  |  |  |  |  | $ 22.1 |  | $ 79.5 | $ 60.1 |  |  |  |  |
Implementation period used to calculate return on plan assets (in years) | 4 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gains or losses includible in cost amortized to extent exceeds benefit obligations or market-related value of plan assets, percentage. | 10.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Recovery in rates for the qualified pension plans base allowance |  |  |  |  |  | 15.5 | 4.8 | 10.0 |  |  |  |  |  |  |  |  |
Anticipated Contributions to pension plans for qualified trust | 26.4 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Anticipated contributions to pension plans for non-qualified plans | 0.5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Medical insurance available until age is reached after early retirement | 65 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amortization period for transition obligation excluded from postretirement benefit cost (in years) | 20 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net pension cost |  |  |  |  |  |  |  |  | 27.4 | [1] | 17.5 | 20.1 | 9.1 | 9.1 | [1] | 9.5 | 9.5
Recovery in rates for postretirement benefit |  |  |  | 9.5 | 7.6 |  |  |  |  |  |  |  |  |  |  |  |
Current investment policy targets an asset allocation to equity securities |  |  |  |  |  |  |  |  |  |  |  |  | 60.00% | 60.00% |  |  |
Investment policy targets asset allocation to debt securities |  |  |  |  |  |  |  |  |  |  |  |  | 40.00% | 40.00% |  |  |
Anticipated contributions to the postretirement plans for qualified trusts |  |  |  |  |  |  |  |  |  |  |  |  |  | 18.1 |  |  |
Anticipated payment directly to participants in postretirement plan |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.3 |  |  |
Other Plans [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
401(K) plans, cost of defined contributions | $ 6.7 | $ 5.0 | $ 3.8 |  |  |  |  |  |  |  |  |  |  |  |  |  |
[1] | Includes Alagasco.

X
- Definition Anticipated contributions to the pension plans for fiscal year 2012 for non-qualified plans. + References No definition available. + Details
Name: | lg_AnticipatedContributionsToPensionPlansNonQualifiedTrusts
Namespace Prefix: | lg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Anticipated contributions to the pension plans for the next fiscal year for qualified trusts. + References No definition available. + Details
Name: | lg_AnticipatedContributionsToPensionPlansQualifiedTrusts
Namespace Prefix: | lg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Anticipated contribution to the postretirement plans for the next fiscal year for qualified trusts. + References No definition available. + Details
Name: | lg_AnticipatedContributionsToPostretirementPlansQualifiedTrusts
Namespace Prefix: | lg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Anticipated payment to the postretirement plans participants for the next fiscal year for non-qualified trusts. + References No definition available. + Details
Name: | lg_AnticipatedPaymentDirectlyToParticipantsInPostretirementPlan
Namespace Prefix: | lg_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Current investment policy that target allocation of assets to equity securities. + References No definition available. + Details
Name: | lg_CurrentInvestmentPolicyTargetsAssetAllocationToEquitySecurities
Namespace Prefix: | lg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Defined Benefit Plan, Lump-sum Payment Recognized as Settlement Gain (Loss), Minimum Threshold + References No definition available. + Details
Name: | lg_DefinedBenefitPlanLumpsumPaymentRecognizedasSettlementGainLossMinimumThreshold
Namespace Prefix: | lg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Reflects the upper limit on age eligibility, post early retirement, when medical insurance is available to retiree. + References No definition available. + Details
Name: | lg_DefinedBenefitPlanMedicalInsuranceOfferedPostEarlyRetirementUntilAgeMaximum
Namespace Prefix: | lg_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The total amount of periodic benefit cost for defined benefit plans for the period after the impact of regulatory adjustment. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain or loss, prior service cost or credit, transition asset or obligation, and gain or loss due to settlements or curtailments. + References No definition available. + Details
Name: | lg_DefinedBenefitPlanNetPeriodicBenefitCostAfterRegulatoryAdjustment
Namespace Prefix: | lg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- 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. + Details
Name: | lg_GainsOrLossesIncludibleInCostAmortizedToExtentExceedsProjectedBenefitObligationsOrMarketRelatedValueOfPlanAssetsPercentage
Namespace Prefix: | lg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- 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. + References No definition available. + Details
Name: | lg_ImplementationPeriodUsedToCalculateReturnOnPlanAssets
Namespace Prefix: | lg_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Current investment policy that target allocation of assets to debt securities. + References No definition available. + Details
Name: | lg_InvestmentPolicyTargetsAssetAllocationToDebtSecurities
Namespace Prefix: | lg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Lump-sum payments recognized as settlements + References No definition available. + Details
Name: | lg_LumpSumPaymentsRecognizedAsSettlements
Namespace Prefix: | lg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | lg_OtherPlansAbstract
Namespace Prefix: | lg_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amortization period for transition obligation not yet in postretirement benefit costs. + References No definition available. + Details
Name: | lg_PostretirementBenefitCostAmortizationPeriod
Namespace Prefix: | lg_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- 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. + Details
Name: | lg_PostretirementBenefitPlansRecoveryinRatesBaseAllowance
Namespace Prefix: | lg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- 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. + Details
Name: | lg_RateRecoveryOfBenefitCosts
Namespace Prefix: | lg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of the cost recognized during the period for defined contribution plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6414718&loc=d3e28014-114942 + Details
Name: | us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration