Document And Entity Information (USD $)	12 Months Ended
	Dec. 31, 2011	Jun. 30, 2011	Mar. 01, 2012 Class A voting [Member]	Mar. 01, 2012 Class B non-voting [Member]
Entity Information [Line Items]
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		$ 199,155,221
Entity Common Stock, Shares Outstanding			2,623,109	12,225,348
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2011