Acquisitions and Dispositions	12 Months Ended
Dec. 31, 2023
Business Combination and Asset Acquisition [Abstract]
Acquisitions and Dispositions	13. ACQUISITONS AND DISPOSITIONS On September 30, 2022, RLI Corp. completed the sale of its equity method investment in Maui Jim to Kering Eyewear for cash proceeds of $687 million. A net realized gain of $571 million was recognized during 2022, and the payout of the working capital escrow during 2023 resulted in the recognition of an additional $14 million realized gain. The gains were recorded in the net realized gain line item of the statement of earnings.

The entire disclosure for business combinations, including leverage buyout transactions (as applicable), and divestitures. This may include a description of a business combination or divestiture (or series of individually immaterial business combinations or divestitures) completed during the period, including background, timing, and assets and liabilities recognized and reclassified or sold. This element does not include fixed asset sales and plant closings.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 805
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//805/tableOfContent

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 205
-SubTopic 20
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//205-20/tableOfContent

Name:	us-gaap_MergersAcquisitionsAndDispositionsDisclosuresTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration