v3.6.0.2

Fair Value - Summary of Combined Fair Value of Assets that Incurred Impairments (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2014
Fair Value Disclosures [Abstract] |  |
Amount of impairment incurred | $ 407 | $ 10,508
Combined fair value of assets incurring impairment, after impairment charges | $ 1,380 | $ 6,000

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- Definition Impaired assets, fair value disclosure after impairment charges. + References No definition available. + Details
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Namespace Prefix: | phii_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration