The total dollar amount of debt and equity securities authorized to be issued.

No definition available.

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The total dollar amount of debt and equity securities available to be issued.

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No definition available.

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Total outstanding indebtedness arising out of any other credit agreements, as stated in the public debt indentures relating to senior notes and debentures, as well as certain revolving credit agreements.

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No definition available.

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Maximum available borrowing capacity under the credit facility with consideration of any additional commited line portions under the accordion feature that could be borrowed against with the approval of the issuing banks.

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No definition available.

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The net proceeds from the issuance of the debt.

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No definition available.

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- Definition

For covenant purposes, total debt divided by total capitalization including original issue discount, short-term debt, capital leases, operating leases and guaranty obligations.

+ References

No definition available.

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- Definition

Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(a)(3))
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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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No definition available.

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Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Publisher SEC
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- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Contractual interest rate for funds borrowed, under the debt agreement.

+ 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

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

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- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
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- Definition

Gross amount of debt extinguished.

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No definition available.

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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

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Carrying amount of long-term debt, net of unamortized discount or premium, excluding amounts to be repaid within one year or the normal operating cycle, if longer (current maturities). Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Debt (Details) - USD ($)		3 Months Ended
Debt (Details) - USD ($)	Oct. 15, 2014	Dec. 31, 2015	Sep. 30, 2015	Sep. 30, 2014
Debt Instrument [Line Items]
Net Proceeds From Issuance Of Debt	$ 494,000,000
Debt Instrument Carrying Amount		$ 2,460,000,000	$ 2,460,000,000
Debt Instrument, Unamortized Discount		4,526,000	4,612,000
Long-term debt		2,455,474,000	2,455,388,000
Extinguishment of Debt, Amount	500,000,000
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity		1,300,000,000
Long Term Debt Other Disclosures [Abstract]
Commercial Paper		763,200,000	457,900,000
Debt and Equity Securities Authorized for Issuance		1,750,000,000.00
Debt And Equity Securities Available For Issuance		$ 845,000,000
Required by Covenant [Member]
Line Of Credit Facility [Line Items]
Ratio of Total Debt to Total Capital		70.00%
Actual [Member]
Line Of Credit Facility [Line Items]
Ratio of Total Debt to Total Capital		51.00%
Regulated Operation [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity		$ 1,300,000,000
Unregulated Operation [Member]
Line Of Credit Facility [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity		36,200,000
Minimum [Member] \| Required by Covenant [Member]
Line Of Credit Facility [Line Items]
Excess of Debt		15,000,000
Maximum [Member] \| Required by Covenant [Member]
Line Of Credit Facility [Line Items]
Excess of Debt		100,000,000
Five Year Unsecured Revolving Credit Agreement [Member] \| Regulated Operation [Member]
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity with Accordion Feature		1,500,000,000.0
Five Year Unsecured Revolving Credit Agreement [Member] \| Commercial Paper [Member] \| Regulated Operation [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity		1,250,000,000
Five Year Unsecured Revolving Credit Agreement [Member] \| Uncommitted Revolving Credit Facility [Member] \| Regulated Operation [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity		1,250,000,000
$15 Million Revolving Credit Note [Member] \| Unsecured Revolving Credit Note [Member] \| Unregulated Operation [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity		15,000,000
$25 Million Bank Loan Agreement [Member] \| Unsecured Loan Agreement [Member] \| Regulated Operation [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity		25,000,000
$10 Million Revolving Credit Note [Member] \| Unsecured Revolving Credit Note [Member] \| Regulated Operation [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity		10,000,000
Line of Credit Facility, Remaining Borrowing Capacity		4,100,000
Uncommitted Revolving Credit Facility and Promissory Note (AEH to AEC) [Member] \| Uncommitted Revolving Credit Facility [Member] \| Regulated Operation [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity		500,000,000
Uncommitted Revolving Credit Facility and Promissory Note (AEC to AEH) [Member] \| Uncommitted Revolving Credit Facility [Member] \| Unregulated Operation [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity		$ 500,000,000
Debt Instrument, Basis Spread on Variable Rate		3.00%
$25 Million Uncommitted Facility [Member] \| Uncommitted Revolving Credit Facility [Member] \| Unregulated Operation [Member]
Line Of Credit Facility [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity		$ 25,000,000
Unsecured Senior Notes Due 2017 [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount		$ 250,000,000	$ 250,000,000
Debt Instrument, Interest Rate, Stated Percentage		6.35%	6.35%
Debt Instrument, Maturity Date		Jun. 15, 2017	Jun. 15, 2017
Unsecured Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount		$ 450,000,000	$ 450,000,000
Debt Instrument, Interest Rate, Stated Percentage		8.50%	8.50%
Debt Instrument, Maturity Date		Mar. 15, 2019	Mar. 15, 2019
Unsecured Senior Notes Due 2034 [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount		$ 200,000,000	$ 200,000,000
Debt Instrument, Interest Rate, Stated Percentage		5.95%	5.95%
Debt Instrument, Maturity Date		Oct. 15, 2034	Oct. 15, 2034
Unsecured Senior Notes Due 2041 [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount		$ 400,000,000	$ 400,000,000
Debt Instrument, Interest Rate, Stated Percentage		5.50%	5.50%
Debt Instrument, Maturity Date		Jun. 15, 2041	Jun. 15, 2041
Unsecured Senior Notes Due 2043 [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount		$ 500,000,000	$ 500,000,000
Debt Instrument, Interest Rate, Stated Percentage		4.15%	4.15%
Debt Instrument, Maturity Date		Jan. 15, 2043	Jan. 15, 2043
Unsecured Senior Notes Due 2044 [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount	$ 500,000,000	$ 500,000,000	$ 500,000,000
Debt Instrument, Interest Rate, Stated Percentage	4.125%	4.125%	4.125%
Debt Instrument, Maturity Date		Oct. 15, 2044	Oct. 15, 2044
Debt Instrument, Interest Rate, Effective Percentage	4.086%
Medium Term Notes Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount		$ 10,000,000	$ 10,000,000
Debt Instrument, Interest Rate, Stated Percentage		6.67%	6.67%
Debt Instrument, Maturity Date		Dec. 15, 2025	Dec. 15, 2025
Unsecured Debentures Due 2028 [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount		$ 150,000,000	$ 150,000,000
Debt Instrument, Interest Rate, Stated Percentage		6.75%	6.75%
Debt Instrument, Maturity Date		Jul. 15, 2028	Jul. 15, 2028
Unsecured Senior Notes Due 2014 [Member]
Debt Instrument [Line Items]
Debt Instrument Carrying Amount				$ 500,000,000
Debt Instrument, Interest Rate, Stated Percentage			4.95%