The impact of the adoption of Topic 326 on the allowance for credit losses on unfunded commitments, effective 1/1/20.

No definition available.

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- Definition

[Line Items] for Commitments and Contingencies Disclosure [Table]

+ References

No definition available.

+ Details

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- Definition

This amount represents a reserve for exposure to losses from the obligation to repurchase previously sold residential mortgage loans.

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No definition available.

+ Details

Name:	pre_ReserveForExposureToLossesFromLoanRepurchases
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This represents the unpaid principal balance of loans repurchased.

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No definition available.

+ Details

Name:	pre_UnpaidPrincipalBalanceOfLoansRepurchased
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The face amount of financial assets, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

+ References

No definition available.

+ Details

Name:	us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountAsset
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121611286&loc=d3e11927-110247

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82919202-210446

+ Details

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Balance Type:	credit
Period Type:	instant

- Details

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- Details

Name:	pre_CommitmentsToExtendCreditAxis=pre_CommitmentsToExtendCreditOnStandbyLettersOfCreditMember
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Data Type:	na
Balance Type:
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- Details

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Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Line Items]
Adoption of ASC 326		$ 1,483
ACL on unfunded commitments	$ 2,382		$ 293
Unpaid principal balance of loans repurchased	1,100		1,700
Reserve for loans repurchases	300		170
Unfunded Loan Commitment [Member]
Commitments and Contingencies Disclosure [Line Items]
Adoption of ASC 326		$ 1,500
Commitments to extend credit on standby letters of credit [Member] \| Commitments to Extend Credit [Member]
Commitments and Contingencies Disclosure [Line Items]
Contract amount	$ 11,709		$ 13,710