v3.6.0.2

Investments (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract] |
Components of Investments | Investments consisted of the following as of December 31, 2016:
|  |  |  |  | Unrealized |  |  | Unrealized |  |  | Fair |
|  | Cost Basis |  |  | Gains |  |  | Losses |  |  | Value |
|  | (Thousands of dollars) |
Investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market mutual funds |  | $ | 18,118 |  |  | $ | — |  |  | $ | — |  |  | $ | 18,118 |
Commercial paper |  |  | 27,906 |  |  |  | — |  |  |  | (39 | ) |  |  | 27,867 |
U.S. government agencies |  |  | 13,295 |  |  |  | — |  |  |  | (32 | ) |  |  | 13,263 |
Corporate bonds and notes |  |  | 244,202 |  |  |  | 2 |  |  |  | (622 | ) |  |  | 243,582 |
Subtotal |  |  | 303,521 |  |  |  | 2 |  |  |  | (693 | ) |  |  | 302,830 |
Deferred compensation plan assets included in other assets |  |  | 2,394 |  |  |  | — |  |  |  | — |  |  |  | 2,394 |
Total |  | $ | 305,915 |  |  | $ | 2 |  |  | $ | (693 | ) |  | $ | 305,224 |
Investments consisted of the following as of December 31, 2015:
|  |  |  |  | Unrealized |  |  | Unrealized |  |  | Fair |
|  | Cost Basis |  |  | Gains |  |  | Losses |  |  | Value |
|  | (Thousands of dollars) |
Investments: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Money market mutual funds |  | $ | 18,181 |  |  | $ | — |  |  | $ | — |  |  | $ | 18,181 |
Commercial paper |  |  | 5,986 |  |  |  | — |  |  |  | (5 | ) |  |  | 5,981 |
U.S. government agencies |  |  | 11,499 |  |  |  | — |  |  |  | (30 | ) |  |  | 11,469 |
Corporate bonds and notes |  |  | 265,069 |  |  |  | — |  |  |  | (841 | ) |  |  | 264,228 |
Subtotal |  |  | 300,735 |  |  |  | — |  |  |  | (876 | ) |  |  | 299,859 |
Deferred compensation plan assets included in other assets |  |  | 2,294 |  |  |  | — |  |  |  | — |  |  |  | 2,294 |
Total |  | $ | 303,029 |  |  | $ | — |  |  | $ | (876 | ) |  | $ | 302,153 |
Cost and Fair Value of Debt Investments Based on Maturities | The following table presents the cost and fair value of our debt investments based on maturities as of December 31,
|  | 2016 |  |  | 2015 |
|  | Amortized |  |  | Fair |  |  | Amortized |  |  | Fair |
|  | Costs |  |  | Value |  |  | Costs |  |  | Value |
|  | (Thousands of dollars) |
Due in one year or less |  | $ | 184,587 |  |  | $ | 184,334 |  |  | $ | 152,444 |  |  | $ | 152,212 |
Due within two years |  |  | 100,816 |  |  |  | 100,378 |  |  |  | 130,110 |  |  |  | 129,466 |
Total |  | $ | 285,403 |  |  | $ | 284,712 |  |  | $ | 282,554 |  |  | $ | 281,678 |
Average Coupon Rate Percentage and Average Days to Maturity of Debt | The following table presents the average coupon rate percentage and the average days to maturity of our debt investments as of December 31,
|  | 2016 |  |  | 2015 |
|  | Average |  |  | Average |  |  | Average |  |  | Average |
|  | Coupon |  |  | Days To |  |  | Coupon |  |  | Days To |
|  | Rate (%) |  |  | Maturity |  |  | Rate (%) |  |  | Maturity |
Commercial paper |  |  | 1.001 |  |  |  | 184 |  |  |  | 0.553 |  |  |  | 154 |
U.S. government agencies |  |  | 0.970 |  |  |  | 400 |  |  |  | 0.865 |  |  |  | 599 |
Corporate bonds and notes |  |  | 1.745 |  |  |  | 318 |  |  |  | 1.757 |  |  |  | 331 |
Investments in Continuous Unrealized Loss Position for Less Than Twelve Months | The following table presents the fair value and unrealized losses related to our investments that have been in a continuous unrealized loss position for less than twelve months as of December 31,
|  | 2016 |  |  | 2015 |
|  |  |  |  | Unrealized |  |  |  |  |  | Unrealized |
|  | Fair Value |  |  | Losses |  |  | Fair Value |  |  | Losses |
|  | (Thousands of dollars) |
Commercial paper |  | $ | 27,867 |  |  | $ | (39 | ) |  | $ | 5,981 |  |  | $ | (5 | )
U.S. government agencies |  |  | 13,263 |  |  |  | (32 | ) |  |  | 8,969 |  |  |  | (30 | )
Corporate bonds and notes |  |  | 210,836 |  |  |  | (602 | ) |  |  | 232,347 |  |  |  | (793 | )
Total |  | $ | 251,966 |  |  | $ | (673 | ) |  | $ | 247,297 |  |  | $ | (828 | )
Investments in Continuous Unrealized Loss Position For Twelve Months Or More | The following table presents the fair value and unrealized losses related to our investments that have been in a continuous unrealized loss position for twelve months or more as of December 31,
|  | 2016 |  |  | 2015 |
|  |  |  |  | Unrealized |  |  |  |  |  | Unrealized |
|  | Fair Value |  |  | Losses |  |  | Fair Value |  |  | Losses |
|  | (Thousands of dollars) |
Corporate bonds and notes |  | $ | 24,196 |  |  | $ | (20 | ) |  | $ | 28,866 |  |  | $ | (48 | )
Total |  | $ | 24,196 |  |  | $ | (20 | ) |  | $ | 28,866 |  |  | $ | (48 | )

X
- Definition Available for sale continuous unrealized loss position less than twelve months. + References No definition available. + Details
Name: | phii_AvailableForSaleContinuousUnrealizedLossPositionLessThanTwelveMonthsTableTextBlock
Namespace Prefix: | phii_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Available for sale continuous unrealized loss position twelve months or more. + References No definition available. + Details
Name: | phii_AvailableForSaleContinuousUnrealizedLossPositionTwelveMonthsOrMoreTableTextBlock
Namespace Prefix: | phii_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Average coupon rate percentage and average days to maturity of debt. + References No definition available. + Details
Name: | phii_AverageCouponRatePercentageAndAverageDaysToMaturityOfDebtTableTextBlock
Namespace Prefix: | phii_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27337-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27198-111563 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62586-112803 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27161-111563 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition Tabular disclosure of the reconciliation of available-for-sale securities from cost basis to fair value. + References No definition available. + Details
Name: | us-gaap_ScheduleOfAvailableForSaleSecuritiesReconciliationTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration