v3.6.0.2

Employee Benefit Plans - Additional Information (Detail) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2016 USD ($) CompensationPlan | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($)
Defined Benefit Plan Disclosure [Line Items] |  |  |
Aggregate deferred under Compensation Plan | $ 2.4 | $ 2.3 |
Number of incentive compensation plans | CompensationPlan | 3 |  |
Earnings before tax upon achieving a specified earnings threshold | 8.25% |  |
Accrued Incentive Compensation expense | $ 1.6 | 3.0 | $ 11.7
Percentage of employee compensation contribution | 6.00% |  |
Percentage of vesting contribution | 25.00% |  |
Vesting period of employees | 5 years |  |
Matching contribution of employees | $ 10.1 | 11.8 | 11.5
Safety Incentive Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Compensation expense related to incentive plans | $ 0.9 | $ 0.9 | $ 1.0

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- Definition Accrued Incentive Plan Expenses + References No definition available. + Details
Name: | phii_AccruedIncentivePlanExpenses
Namespace Prefix: | phii_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Defined contribution plan employers matching contribution vesting period. + References No definition available. + Details
Name: | phii_DefinedContributionPlanEmployersMatchingContributionVestingPeriod
Namespace Prefix: | phii_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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- Definition Incentive Compensation Expense + References No definition available. + Details
Name: | phii_IncentiveCompensationExpense
Namespace Prefix: | phii_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Incentive distributions maximum threshold percentage. + References No definition available. + Details
Name: | phii_IncentiveDistributionsMaximumThresholdPercentage
Namespace Prefix: | phii_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Definition Number Of Compensation Plans + References No definition available. + Details
Name: | phii_NumberOfCompensationPlans
Namespace Prefix: | phii_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition 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. + Details
Name: | us-gaap_DeferredCompensationLiabilityCurrentAndNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of employer's matching contributions to a defined contribution plan that vests in a given year. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployersMatchingContributionAnnualVestingPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis=phii_SafetyIncentivePlanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |