XML 25 R16.htm IDEA: XBRL DOCUMENT
v3.23.3

Net Investment Income | 9 Months Ended
--- | ---
Sep. 30, 2023
Net Investment Income [Abstract] |
Net Investment Income | Net Investment Income Net investment income consisted of the following:
| For the Three Months Ended September 30, |  | For the Nine Months Ended September 30,
(In thousands) | 2023 |  | 2022 |  | 2023 |  | 2022
Investment income (loss) earned on: |  |  |  |  |  |  |
Fixed maturity securities, including cash and cash equivalents and loans receivable | $ | 239,727 |  |  | $ | 146,051 |  |  | $ | 653,200 |  |  | $ | 371,724 |
Arbitrage trading account (1) | 17,876 |  |  | 10,694 |  |  | 53,168 |  |  | 24,008 |
Equity securities | 12,714 |  |  | 14,650 |  |  | 41,714 |  |  | 38,303 |
Investment funds | 4,450 |  |  | 36,045 |  |  | 5,444 |  |  | 121,919 |
Real estate | (1,986) |  |  | (2,297) |  |  | (7,821) |  |  | (1,702) |
Gross investment income | 272,781 |  |  | 205,143 |  |  | 745,705 |  |  | 554,252 |
Investment expense | (1,837) |  |  | (2,327) |  |  | (6,211) |  |  | (6,350) |
Net investment income | $ | 270,944 |  |  | $ | 202,816 |  |  | $ | 739,494 |  |  | $ | 547,902 |
(1) Net investment income includes earnings from trading account receivables from brokers and clearing organizations.

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

X
- Definition Net Investment Income [Text Block] + References No definition available. + Details
Name: | wrb_NetInvestmentIncomeTextBlock
Namespace Prefix: | wrb_
Data Type: | dtr-types1:textBlockItemType
Balance Type: | na
Period Type: | duration