Eligible percentage of common stock over performance period target award maximum.

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- Definition

Eligible percentage of common stock over performance period target award minimum.

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- Definition

Initial pricing of equity forward instruments.

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- Definition

Minimum ratio of equity to capitalization.

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No definition available.

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- Definition

Public offering price.

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- Definition

Purchases of common stock through dividend reinvestment plan maximum.

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No definition available.

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- Definition

Purchases of common stock through dividend reinvestment plan minimum.

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No definition available.

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- Definition

Share based compensation arrangement by share based award expiration of date of stock options.

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No definition available.

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- Definition

Share based compensation arrangement by share based payment award restricted stock units granted to non employee directors.

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No definition available.

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- Definition

Underwriting discount per share.

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No definition available.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section F

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- Definition

Amount of restricted net assets of consolidated and unconsolidated subsidiaries as of the end of the most recently completed fiscal year.

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-Publisher FASB

-Name Accounting Standards Codification

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-Subparagraph (SX 210.4-08.(e)(3)(ii))

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-Name Regulation S-X (SX)

-Number 210

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-Paragraph e

-Subparagraph 3

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- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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-Publisher FASB

-Name Accounting Standards Codification

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-Name Regulation S-X (SX)

-Number 210

-Section 02

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-Article 5

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- Definition

The compensation expense recognized during the period pertaining to the deferred compensation arrangement.

+ References

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Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

+ References

No definition available.

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- Definition

The forward price on the price risk forward or futures contract, such as a gas futures contract.

+ References

No definition available.

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- Definition

Unrecognized cost of unvested share-based compensation awards.

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-Name Accounting Standards Codification

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The cash inflow from the issuance of common stock, preferred stock, treasury stock, stock options, and other types of equity.

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

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-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (a)

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- Definition

The cumulative amount of the reporting entity's undistributed earnings or deficit.

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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-Name Regulation S-X (SX)

-Number 210

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-Subparagraph (SX 210.5-02.31(a)(3))

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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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-Section 50

-Paragraph 2

-Subparagraph (a)(1)

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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- Definition

Net number of share options (or share units) granted during the period.

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-Name Accounting Standards Codification

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- Definition

Number of shares issued during the period from a dividend reinvestment plan (DRIP). A dividend reinvestment plan allows the shareholders to reinvest dividends paid to them by the entity on new issues of stock by the entity.

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Stock-Based Compensation, Dividend Restrictions, and Calculations of Earnings Per Share of Common Stock - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 27, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock authorized for issuance	10,000,000
Stock-based compensation expense	$ 0	$ 0	$ 0
Eligible percentage of common stock over the performance period target award minimum	25.00%
Eligible percentage of common stock over the performance period target award maximum	200.00%
Requisite service period (years)	3 years
Restricted stock units were granted to each non-employee director	21,138	37,735
Vesting Period	1 year	1 year
Unrecognized compensation expense	12,000,000
Costs recognized, weighted average period (years)	2 years
Stock option expiration (years)	10 years
Stock options outstanding	0
Recognized compensation expense	1,000,000	0	0
Deferred compensation balance	2,000,000	2,000,000
Ratio of equity to total capitalization	30.00%
Retained earnings	565,000,000	595,000,000
Restricted net assets for consolidated subsidiaries	2,547,000,000
Shares of PHI common stock	17,922,077us-gaap_CommonStockSharesIssued
Public offering price	$ 19.25pom_PublicOfferingPrice
Underwriting discount	$ 0.67375pom_UnderwritingDiscountPerShare
Initial pricing of equity forward instruments	$ 18.57625
Forward sale price				17.39us-gaap_DerivativeForwardPrice
Proceeds from equity forward transaction	312,000,000
Purchases of common stock minimum per calendar month	25
Purchases of common stock maximum per calendar year	300,000
Shares issued and sold under the DRP	1,000,000	2,000,000	2,000,000
2012 LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock authorized for issuance	8,000,000
Performance Based Restricted Stock Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 18,000,000	$ 12,000,000	$ 11,000,000