XML 44 R31.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Fair Value Measurement (Quantitative Information Regarding Level 3 Valuations) (Details) - Level 3 [Member] - USD ($) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2017 | Dec. 31, 2016
Corporate debt with limited observable inputs [Member] |  |
Assets: |  |
Fair Value at | $ 18,914 | $ 14,810
Corporate debt with limited observable inputs [Member] | Market comparable securities valuation technique [Member] | Minimum [Member] |  |
Assets: |  |
Comparability Adjustment | 0.00% |
Corporate debt with limited observable inputs [Member] | Market comparable securities valuation technique [Member] | Maximum [Member] |  |
Assets: |  |
Comparability Adjustment | 5.00% |
Corporate debt with limited observable inputs [Member] | Market comparable securities valuation technique [Member] | Weighted Average [Member] |  |
Assets: |  |
Comparability Adjustment | 2.50% |
Corporate debt with limited observable inputs [Member] | Discount cash flows valuation technique [Member] | Minimum [Member] |  |
Assets: |  |
Comparability Adjustment | 0.00% |
Corporate debt with limited observable inputs [Member] | Discount cash flows valuation technique [Member] | Maximum [Member] |  |
Assets: |  |
Comparability Adjustment | 5.00% |
Corporate debt with limited observable inputs [Member] | Discount cash flows valuation technique [Member] | Weighted Average [Member] |  |
Assets: |  |
Comparability Adjustment | 2.50% |
Other asset-backed securities [Member] |  |
Assets: |  |
Fair Value at | $ 3,002 | 3,007
Other asset-backed securities [Member] | Market comparable securities valuation technique [Member] | Minimum [Member] |  |
Assets: |  |
Comparability Adjustment | 0.00% |
Other asset-backed securities [Member] | Market comparable securities valuation technique [Member] | Maximum [Member] |  |
Assets: |  |
Comparability Adjustment | 5.00% |
Other asset-backed securities [Member] | Market comparable securities valuation technique [Member] | Weighted Average [Member] |  |
Assets: |  |
Comparability Adjustment | 2.50% |
Other asset-backed securities [Member] | Discount cash flows valuation technique [Member] | Minimum [Member] |  |
Assets: |  |
Comparability Adjustment | 0.00% |
Other asset-backed securities [Member] | Discount cash flows valuation technique [Member] | Maximum [Member] |  |
Assets: |  |
Comparability Adjustment | 5.00% |
Other asset-backed securities [Member] | Discount cash flows valuation technique [Member] | Weighted Average [Member] |  |
Assets: |  |
Comparability Adjustment | 2.50% |
Other investments [Member] |  |
Assets: |  |
Fair Value at | $ 903 | $ 3
Other investments [Member] | Discount cash flows valuation technique [Member] | Minimum [Member] |  |
Assets: |  |
Comparability Adjustment | 0.00% |
Other investments [Member] | Discount cash flows valuation technique [Member] | Maximum [Member] |  |
Assets: |  |
Comparability Adjustment | 10.00% |
Other investments [Member] | Discount cash flows valuation technique [Member] | Weighted Average [Member] |  |
Assets: |  |
Comparability Adjustment | 5.00% |

X
- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_AssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition Percentage of adjustment to the observed price for a similar asset or liability when an identical transaction does not exist, used as an input to measure fair value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueInputsComparabilityAdjustments
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=pra_CorporateDebtLimitedObservableInputsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=us-gaap_MarketApproachValuationTechniqueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_WeightedAverageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ValuationTechniqueAxis=us-gaap_IncomeApproachValuationTechniqueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_AssetBackedSecuritiesSecuritizedLoansAndReceivablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByAssetClassAxis=us-gaap_OtherInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |