Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Consolidated Statements of Comprehensive Income [Abstract]
Net earnings									$ 13,108	$ 14,124	$ 29,951
Other comprehensive income before income taxes:
Unrealized gains on securities available-for-sale									19,449	21,518	17,850
Amortization of gain on hedging transactions									(81)	(78)	(739)
Reclassification adjustment for realized gains included in net earnings									(9,693)	(10,966)	(2,251)
Total other comprehensive income before income taxes									9,675	10,474	14,860
Income tax expense related to items of other comprehensive income									585	4,082	2,069
Other comprehensive income net of income taxes									9,090	6,392	12,791
Comprehensive income	(5,502)	11,824	7,438	7,291	(4,186)	15,489	10,495	(4,668)	22,198	20,516	42,742
Less: Comprehensive income (loss) attributable to the non-controlling interest									1,147	3,386	(469)
Comprehensive income attributable to American Safety Insurance Holdings, Ltd.									$ 21,051	$ 17,130	$ 43,211