v3.7.0.1

Stock-Based Compensation - Additional Information (Detail) - shares | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2017 | Jun. 30, 2016 | Jun. 30, 2017 | Jun. 30, 2016
Time-based Restricted Units [Member] |  |  |  |
Stock Based Compensation [Line Items] |  |  |  |
Restricted units awarded to managers (shares) | 417,266 | 14,288 | 447,477 | 14,288,000
Performance-based Restricted Units [Member] |  |  |  |
Stock Based Compensation [Line Items] |  |  |  |
Restricted units awarded to managers (shares) | 365,539 | 5,102 | 365,539,000 | 308,163

X
- Definition Stock Based Compensation [Line Items] + References No definition available. + Details
Name: | phii_StockBasedCompensationLineItems
Namespace Prefix: | phii_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AwardTypeAxis=phii_TimeBasedAwardsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=phii_PerformanceBasedAwardsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |