Loans (TDRs) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Recorded investment	$ 15,763	$ 869
Specific reserves on troubled debt restructurings	159	97
Additional commitments to lend to borrowers with TDRs	0	0
Performing Financial Instruments [Member]
Recorded investment	13,418	377
Nonperforming Financial Instruments [Member]
Recorded investment	$ 2,345	$ 492

The amount of specific reserves on troubled debt restructurings.

No definition available.

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Namespace Prefix:	pre_
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Balance Type:	credit
Period Type:	instant

- Definition

Amount of financing receivable modified as troubled debt restructuring.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953676-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121585226&loc=d3e18845-111554

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Amount of unfunded portion of contractual agreement to lend funds to borrower for financing receivable modified as troubled debt restructuring.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121585226&loc=d3e18794-111554

+ Details

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Period Type:	instant

- Details

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- Details

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