Unaudited Selected Quarterly Financial Information (Schedule of Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Unaudited Selected Quarterly Financial Information [Abstract]
Total revenue	$ 97,254	$ 97,618	$ 91,052	$ 90,028	$ 90,071	$ 93,684	$ 97,197	$ 91,450	$ 375,952	$ 372,402	$ 337,366
Total expense	103,428	90,442	89,565	84,039	84,984	83,849	87,922	83,761	367,474	340,516	318,584
Income (loss) before tax	(6,174)	7,176	1,487	5,989	5,087	9,835	9,275	7,689	8,478	31,886	18,782
Income tax expense (benefit)	(2,512)	2,128	421	1,915	1,641	3,137	2,899	2,346	1,952	10,023	5,353
Net income (loss)	$ (3,662)	$ 5,048	$ 1,066	$ 4,074	$ 3,446	$ 6,698	$ 6,376	$ 5,343	6,526	21,863	13,429
Net income (loss) attributable to Hallmark Financial Services, Inc.									$ 6,526	$ 21,863	$ 13,429
Basic earnings (loss) per share:	$ (0.20)	$ 0.27	$ 0.06	$ 0.21	$ 0.18	$ 0.35	$ 0.33	$ 0.28	$ 0.35	$ 1.14	$ 0.70
Diluted earnings (loss) per share:	$ (0.20)	$ 0.27	$ 0.06	$ 0.21	$ 0.17	$ 0.35	$ 0.33	$ 0.28	$ 0.34	$ 1.13	$ 0.69