Investments, Limited Partnerships (Details) $ in Thousands	12 Months Ended
Dec. 31, 2019 USD ($) Investment	Dec. 31, 2018 USD ($)
Limited Partners' Capital Account [Abstract]
Regulatory deposits with various insurance departments in United States and Canada, fair value	$ 99,763	$ 87,981
Time certificate of deposit included in short-term investments	$ 1,000
Percentage of fixed income securities invested in investment grade fixed income	92.00%
Number of fixed income investments issued with guarantees \| Investment	0
Fixed income investment below investment grade	$ 61,181
Percentage of fixed income investment to total invested assets	6.30%
Net unrealized gain position of investments	$ 684
Limited Partnerships [Member]
Limited Partners' Capital Account [Abstract]
Commitment to make additional contributions to various limited partnerships	$ 350

The commitment amount of additional contribution to various limited partnership.

No definition available.

Name:	ptvc_CommitmentToMakeAdditionalContributionsToVariousLimitedPartnerships
Namespace Prefix:	ptvc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

fixed maturity investments consists of bonds rated as less than investment grade at year end.

+ References

No definition available.

+ Details

Name:	ptvc_FixedMaturityInvestmentBelowInvestmentGrade
Namespace Prefix:	ptvc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fixed income investments which were orginally issued with gurantees by third-party insurance company.

+ References

No definition available.

+ Details

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

- Definition

This element represents percentage of fixed maturities invested in investment grade fixed maturity.

+ References

No definition available.

+ Details

Name:	ptvc_PercentageOfFixedMaturitiesInvestedInInvestmentGradeFixedMaturityInHundredths
Namespace Prefix:	ptvc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of fixed maturity investments to total invested assets.

+ References

No definition available.

+ Details

Name:	ptvc_PercentageOfFixedMaturityInvestmentInvestedAssets
Namespace Prefix:	ptvc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of regulatory deposits with state regulatory authorities in connection with capital requirements.

+ References

No definition available.

+ Details

Name:	ptvc_RegulatoryDepositsFairValue
Namespace Prefix:	ptvc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_LimitedPartnersCapitalAccountAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Any certificate of deposit or savings account held by a bank or other financial institution for a short-term specified period of time. Because of their short-term, time deposits are considered highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The increase (decrease), resulting in a gain, in the difference between the fair value and the carrying value, or in the comparative fair values, of securities held at each balance sheet date, that was included in earnings for the period.

+ References

No definition available.

+ Details

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

- Details

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