XML 59 R42.htm IDEA: XBRL DOCUMENT
v3.23.1

Summary of Significant Accounting Policies - Schedule of Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities | $ 8,329 | $ 8,855
Level 1 |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities | 5,497 | 76
Level 2 |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities | 2,832 | 8,779
Level 3 |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities | 0 | 0
U.S. government obligations |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities | 1,478 | 667
U.S. government obligations | Level 1 |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities | 0 | 0
U.S. government obligations | Level 2 |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities | 1,478 | 667
U.S. government obligations | Level 3 |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities | 0 | 0
Corporate obligations |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities | 6,851 | 8,112
Corporate obligations | Level 1 |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities | 5,497 | 0
Corporate obligations | Level 2 |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities | 1,354 | 8,112
Corporate obligations | Level 3 |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities | $ 0 | 0
Marketable equity securities |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities |  | 76
Marketable equity securities | Level 1 |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities |  | 76
Marketable equity securities | Level 2 |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities |  | 0
Marketable equity securities | Level 3 |  |
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items] |  |
Marketable Securities |  | $ 0

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_DebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of investment in marketable security. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.4) -URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878 + Details
Name: | us-gaap_MarketableSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=prph_USGovernmentObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=prph_CorporateObligationsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=prph_MarketableEquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |