Basis of Presentation [Abstract]

No definition available.

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- Definition

The deferral, which can be either a positive or negaitive amount depending on whether a collection from or refund to customers results, of the amounts recorded in net income for energy useage by customers on a weather adjusted basis that is different from base rates as determined under the Company's decoupling mechanism, expected to be recovered or refunded in future periods.

+ References

No definition available.

+ Details

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- Definition

Number of incorporated cities in service area.

+ References

No definition available.

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- Definition

Includes residential, commercial and industrial.

+ References

No definition available.

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- Definition

Service area population as a percent of the state's population.

+ References

No definition available.

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- Definition

Service Area Population

+ References

No definition available.

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- Definition

Approximate square miles of service area.

+ References

No definition available.

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- Definition

The increase (decrease) during the reporting period in the amount of (a) prepayments by customers for goods or services to be provided at a later date, (b) the amount of customer money held in customer accounts, including security deposits, collateral for a current or future transactions, initial payment of the cost of acquisition or for the right to enter into a contract or agreement, or (c) a combination of (a) and (b).

+ References

No definition available.

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- Definition

Amount after tax of (increase) decrease in the value of the projected benefit obligation related to a change in an actuarial assumption and increase (decrease) in the value of the plan assets resulting from experience different from that assumed, that has not been recognized in net periodic benefit (cost) credit.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669646-108580

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=66004124&loc=d3e637-108580

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (j)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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- Definition

Amount after tax of other comprehensive income (loss) attributable to parent entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (c)(3)
-URI http://asc.fasb.org/extlink&oid=64809438&loc=SL4573702-111684

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=68079674&loc=SL4569643-111683

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- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ 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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Basis of Presentation (Details) shares in Millions	3 Months Ended		9 Months Ended
Basis of Presentation (Details) shares in Millions	Sep. 30, 2016 USD ($) mi² retail_customers shares	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) mi² retail_customers shares	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Basis of Presentation [Abstract]
Increase (Decrease) in Customer Advances and Deposits				$ (3,000,000)
Service Area Sq Miles \| mi²	4,000		4,000
Incorporated Cities	51		51
Number of Retail Customers \| retail_customers	863,000		863,000
Service Area Population \| shares	1.8		1.8
Percent of State's Population	46.00%		46.00%
Decoupling Mechanism Deferrals, Net				10,000,000
Other Comprehensive Income	$ 0		$ 0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Net of Tax			(1)	$ 0
Unamortized Debt Issuance Expense	$ 11,000,000		$ 11,000,000		$ 11,000,000