Differences Between Provisions for Income Taxes and Provisions Calculated at Statutory Federal Tax Rate (Detail)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Examination [Line Items]
Statutory Federal Income Tax Rate	34.00%	34.00%	34.00%
State Income Taxes, net	2.00%	5.00%	5.00%
Utility Plant Differences	(1.00%)	(2.00%)	(2.00%)
Other, net	1.00%		1.00%
Effective Income Tax Rate	36.00%	37.00%	38.00%

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

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-Publisher SEC

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-Number 210

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

+ References

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-Subparagraph (SAB TOPIC 6.I)

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to other adjustments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Effective Income Tax Rate Reconciliation Domestic Income Tax Rate Differential

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