Computation of Basic and Diluted Loss Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Earnings Per Share Disclosure [Line Items]
Earnings (loss) from continuing operations	$ (2,286)	$ 3,786	$ (5,012)	$ (1,667)
Loss attributable to noncontrolling interest		(31)		(93)
Earnings (loss) from continuing operations attributable to Signature Group Holdings, Inc.	(2,286)	3,817	(5,012)	(1,574)
Loss from discontinued operations, net of income taxes	(342)	(2,542)	(2,753)	(7,518)
Net earnings (loss) attributable to Signature Group Holdings, Inc.	$ (2,628)	$ 1,275	$ (7,765)	$ (9,092)
Weighted average basic shares outstanding	116,328,282	114,200,106	115,879,042	112,810,889
Weighted average diluted shares outstanding	116,328,282	114,415,778	115,879,042	112,810,889
Basic and diluted earnings (loss) per share:
Continuing operations	$ (0.02)	$ 0.03	$ (0.04)	$ (0.01)
Discontinued operations		$ (0.02)	$ (0.03)	$ (0.07)
Basic and diluted earnings (loss) per share	$ (0.02)	$ 0.01	$ (0.07)	$ (0.08)