Equity And Earnings Per Share (Narrative) (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	6 Months Ended
Mar. 05, 2012	Jun. 30, 2012 Month
Shares of PHI common stock	17,922,077
Forward sale agreement settlement date, minimum	Mar. 05, 2012
Public offering price		$ 19.25
Underwriting discount		$ 0.67375
Initial Pricing of equity forward instruments		$ 18.57625
Forward sale agreement settlement period, months		12
Forward sale agreement settlement date, maximum		Mar. 05, 2013
Physical settlement value		$ 323
Estimated forward instrument settlement cash		$ 13
Forward instrument settlement, shares		640,000

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.

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 210.5-02.29)

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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 30

-Article 5

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant