Unaudited Selected Quarterly Financial Information (Details) (USD $) In Thousands, except Per Share data, 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
Total revenue	$ 88,623	$ 85,620	$ 84,571	$ 82,986	$ 83,102	$ 83,748	$ 78,513	$ 77,408	$ 341,800	$ 322,771	$ 307,060
Total expense	86,336	80,599	88,722	82,769	82,667	83,042	87,856	88,993	338,426	342,558	298,689
Income (loss) before tax	2,287	5,021	(4,151)	217	435	706	(9,343)	(11,585)	3,374	(19,787)	8,371
Income tax expense (benefit)	504	1,350	(2,351)	23	94	602	(9,264)	(386)	(474)	(8,954)	863
Net income (loss)	1,783	3,671	(1,800)	194	341	104	(79)	(11,199)	3,848	(10,833)	7,508
Net income attributable to non-controlling interest	0	258	43	23	30	6	8	14	324	58	105
Net income (loss) attributable to Hallmark Financial Services, Inc.	$ 1,783	$ 3,413	$ (1,843)	$ 171	$ 311	$ 98	$ (87)	$ (11,213)	$ 3,524	$ (10,891)	$ 7,403
Basic earnings (loss) per share:	$ 0.09	$ 0.18	$ (0.10)	$ 0.01	$ 0.02	$ 0.01	$ 0.00	$ (0.56)	$ 0.18	$ (0.55)	$ 0.37
Diluted earnings (loss) per share:	$ 0.09	$ 0.18	$ (0.10)	$ 0.01	$ 0.02	$ 0.01	$ 0.00	$ (0.56)	$ 0.18	$ (0.55)	$ 0.37