Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2022	Feb. 15, 2023	Jun. 30, 2022
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Document Transition Report	false
Entity File Number	1-15202
Entity Registrant Name	W. R. BERKLEY CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	22-1867895
Entity Address, Address Line One	475 Steamboat Road
Entity Address, City or Town	Greenwich,
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06830
City Area Code	203
Local Phone Number	629-3000
Title of 12(b) Security	Common Stock, par value $.20 per share
Trading Symbol	WRB
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 14,340,165,170
Entity Common Stock, Shares Outstanding		263,446,321
Entity Central Index Key	0000011544
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Documents Incorporated by Reference [Text Block]	Portions of the Company’s definitive proxy statement, which will be filed with the Securities and Exchange Commission within 120 days after December 31, 2022, are incorporated herein by reference in Part III.
5.700% Subordinated Debentures due 2058
Entity Information [Line Items]
Title of 12(b) Security	5.700% Subordinated Debentures due 2058
Trading Symbol	WRB-PE
Security Exchange Name	NYSE
5.100% Subordinated Debentures due 2059
Entity Information [Line Items]
Title of 12(b) Security	5.100% Subordinated Debentures due 2059
Trading Symbol	WRB-PF
Security Exchange Name	NYSE
4.250% Subordinated Debentures due 2060
Entity Information [Line Items]
Title of 12(b) Security	4.250% Subordinated Debentures due 2060
Trading Symbol	WRB-PG
Security Exchange Name	NYSE
4.125% Subordinated Debentures due 2061
Entity Information [Line Items]
Title of 12(b) Security	4.125% Subordinated Debentures due 2061
Trading Symbol	WRB-PH
Security Exchange Name	NYSE