Cover Page - shares	9 Months Ended
	Sep. 30, 2021	Nov. 03, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	0-16533
Entity Registrant Name	ProAssurance Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	63-1261433
Entity Address, Address Line One	100 Brookwood Place,
Entity Address, City or Town	Birmingham,
Entity Address, State or Province	AL
Entity Address, Postal Zip Code	35209
City Area Code	(205)
Local Phone Number	877-4400
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	PRA
Security Exchange Name	NYSE
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
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		53,983,561
Entity Central Index Key	0001127703
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31