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Real Estate (Details) - USD ($) $ in Thousands | Mar. 31, 2023 | Dec. 31, 2022
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Real Estate [Abstract] |  |
Properties in operation | $ 1,111,713 | $ 1,114,167
Properties under development | 226,791 | 226,455
Total | $ 1,338,504 | $ 1,340,622

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- Definition The current amount of expenditures for a real estate project that has not yet been completed. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.10) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 + Details
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Balance Type: | debit
Period Type: | instant

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- References No definition available. + Details
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Namespace Prefix: | us-gaap_
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Balance Type: | na
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- Definition Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(d)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 + Details
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Namespace Prefix: | us-gaap_
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- Definition Building and Lease Obligations + References No definition available. + Details
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Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant