Related Parties (Details) $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($) Partnership Director	Mar. 31, 2018 USD ($)
Related Party [Abstract]
Amount withdrawn from partnership	$ 17,214	$ 0
New Vernon India Fund [Member]
Related Party [Abstract]
Ownership interest in limited partnership	4.00%
Amount withdrawn from partnership	$ 5,684
Director [Member] \| New Vernon India Fund [Member]
Related Party [Abstract]
Number of investments \| Partnership	1
Estimated aggregate value of investment in limited partnerships	$ 17,313
Number of related parties \| Director	1
Director [Member] \| Limited Partnerships [Member]
Related Party [Abstract]
Management fees and commissions	$ 48	142
Director [Member] \| Investment Firm Services [Member]
Related Party [Abstract]
Number of related parties \| Director	1
Management fees and commissions	$ 5	$ 27
Market value of equity and fixed maturity securities portfolio	$ 7,899

This element represent the number of related party investments.

No definition available.

Name:	ptvc_NumberOfInvestments
Namespace Prefix:	ptvc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of the Company's directors that are executive officers, directors, and owners of organizations outside of the Company.

+ References

No definition available.

+ Details

Name:	ptvc_NumberOfRelatedPartiesThatAreManagersOfOutsideEntity
Namespace Prefix:	ptvc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The equity interest of partners or other equity holders in a limited partnership.

+ References

No definition available.

+ Details

Name:	ptvc_OwnershipInterestInLimitedPartnership
Namespace Prefix:	ptvc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

Name:	ptvc_RelatedPartyAbstract
Namespace Prefix:	ptvc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Cash inflow received as distributions, returns of capital, or sale proceeds from partnership interests held for investment purposes.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromLimitedPartnershipInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of transactions with related party during the financial reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864

+ Details

Name:	us-gaap_RelatedPartyTransactionAmountsOfTransaction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reflects the sum of all other revenue and income realized from sales and other transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ 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 http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_TradingSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	srt_OwnershipAxis=ptvc_NewVernonIndiaFundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_DirectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=ptvc_RelatedPartyTransactionsLimitedPartnershipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=ptvc_RelatedPartyTransactionsInvestmentFirmServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: