Variable Interest Entities - Additional Information (Detail) (USD $)	6 Months Ended	1 Months Ended		12 Months Ended
	Jun. 30, 2012	Aug. 31, 2012 Amerisafe Capital Trust II [Member]	May 31, 2012 Amerisafe Capital Trust II [Member]	Dec. 31, 2004 Amerisafe Capital Trust II [Member]
Marketable Securities [Line Items]
Proceeds from issuance of trust preferred securities				$ 25,000,000
Purchase of subordinated debt securities				25,800,000
Redemption of debt securities	12,890,000	12,900,000	12,900,000
Subordinated debt securities			$ 12,900,000	$ 25,800,000