Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2012	Jun. 30, 2012	Mar. 01, 2013 Common Class A [Member]	Mar. 01, 2013 Common Class B [Member]
Document and Entity Information [Abstract]
Entity Registrant Name	BALDWIN & LYONS INC
Entity Central Index Key	0000009346
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float		$ 212,152,000
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding			2,623,109	12,290,035
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2012