Stock-Based Compensation, Dividend Restrictions, and Calculations of Earnings Per Share of Common Stock - Additional Information (Detail) (USD $)	1 Months Ended					12 Months Ended
	Feb. 28, 2013	Jan. 31, 2013	Sep. 30, 2012	Apr. 30, 2012	Jan. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Feb. 27, 2013	Dec. 31, 2010
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 awards	45,444	45,444	150,330	150,330	150,330
Unrestricted stock awards			5,305	5,305	5,305
Restricted stock units were granted to each non-employee director						37,735	40,749
Targeted performance criteria						100.00%
Unrecognized compensation expense						11,000,000
Costs recognized, weighted average period (years)						2 years
Stock option expiration (years)						10 years
Stock options outstanding						0
Deferred compensation balance						2,000,000	1,000,000
Ratio of equity to total capitalization						30.00%
Retained earnings						595,000,000	1,077,000,000	1,040,000,000		1,027,000,000
Shares of PHI common stock						17,922,077
Public offering price						$ 19.25
Underwriting discount						$ 0.67375
Initial pricing of equity forward instruments						$ 18.57625
Forward sale price									17.39
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						2,000,000	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
Time-Based Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Retention Awards	2	2	4	4	4
Vesting Period							3 years
Performance Based Restricted Stock Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense						$ 12,000,000	$ 11,000,000	$ 6,000,000
Vesting Period						1 year
Time Based Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Period						3 years
Non Employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Period						1 year	1 year