Operating Results and Other Key Financial Measures of Operating Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Operating revenues	$ 9,777	$ 11,324	$ 34,219	$ 32,738
Operating costs	12,170	12,640	35,504	36,176
Other income (expense)	(3,301)	(910)	(8,350)	(1,223)
Earnings (loss) before income taxes	(5,694)	(2,226)	(9,635)	(4,661)
Income tax expense (benefit)	(7)	(60)	86	22
Loss from continuing operations	(5,687)	(2,166)	(9,721)	(4,683)
Loss attributable to noncontrolling interest
Net earnings (loss) attributable to Signature Group Holdings, Inc.	(172)	(462)	(827)	(3,082)
Net loss	(5,859)	(2,628)	(10,548)	(7,765)
Net loss attributable to Signature Group Holdings, Inc.	(5,859)	(2,628)	(10,548)	(7,765)
Current assets	93,967		93,967		76,113
Total assets	118,695		118,695		125,711
Current liabilities	9,850		9,850		14,013
Total liabilities	69,657		69,657		67,485
Continuing Operations
Segment Reporting Information [Line Items]
Operating costs	12,170	12,640	35,504	36,176
Other income (expense)	(3,301)	(910)	(8,350)	(1,223)
Earnings (loss) before income taxes	(5,694)	(2,226)	(9,635)	(4,661)
Income tax expense (benefit)	(7)	(60)	86	22
Loss from continuing operations	(5,687)	(2,166)	(9,721)	(4,683)
Loss attributable to noncontrolling interest
Net earnings (loss) attributable to Signature Group Holdings, Inc.	(5,687)	(2,166)	(9,721)	(4,683)
Current assets	93,280		93,280		72,499
Total assets	117,427		117,427		121,447
Current liabilities	7,785		7,785		11,721
Total liabilities	60,842		60,842		57,693
Continuing Operations | Operating Segments | Wholesale Electrical Distribution
Segment Reporting Information [Line Items]
Operating costs	8,492	8,489	23,371	22,924
Other income (expense)		(76)		(225)
Earnings (loss) before income taxes	1,738	1,638	4,683	3,958
Income tax expense (benefit)	828	741	1,978	1,668
Loss from continuing operations	910	897	2,705	2,290
Loss attributable to noncontrolling interest
Net earnings (loss) attributable to Signature Group Holdings, Inc.	910	897	2,705	2,290
Current assets	14,921		14,921		15,253
Total assets	36,227		36,227		37,667
Current liabilities	5,596		5,596		10,864
Total liabilities	21,865		21,865		26,012
Continuing Operations | Operating Segments | Signature Special Situations
Segment Reporting Information [Line Items]
Operating costs	4	306	411	786
Other income (expense)	(14)		(14)
Earnings (loss) before income taxes	(369)	917	6,043	5,149
Income tax expense (benefit)	(214)	664	2,284	696
Loss from continuing operations	(155)	253	3,579	4,453
Loss attributable to noncontrolling interest
Net earnings (loss) attributable to Signature Group Holdings, Inc.	(155)	253	3,579	4,453
Current assets	8,844		8,844		12,229
Total assets	16,424		16,424		43,230
Current liabilities	15		15		103
Total liabilities	3,662		3,662		23,539
Continuing Operations | Corporate and Other
Segment Reporting Information [Line Items]
Operating costs	3,776	4,217	12,341	13,450
Other income (expense)	(3,287)	(834)	(8,336)	(998)
Earnings (loss) before income taxes	(7,063)	(4,781)	(20,361)	(13,768)
Income tax expense (benefit)	(621)	(1,465)	(4,176)	(2,342)
Loss from continuing operations	(6,442)	(3,316)	(16,185)	(11,426)
Loss attributable to noncontrolling interest
Net earnings (loss) attributable to Signature Group Holdings, Inc.	(6,442)	(3,316)	(16,185)	(11,426)
Current assets	69,515		69,515		45,017
Total assets	79,858		79,858		72,758
Current liabilities	2,174		2,174		754
Total liabilities	50,397		50,397		40,350
Continuing Operations | Eliminations
Segment Reporting Information [Line Items]
Operating costs	(102)	(372)	(619)	(984)
Loss attributable to noncontrolling interest
Total assets	(15,082)		(15,082)		(32,208)
Total liabilities	(15,082)		(15,082)		(32,208)
Discontinued Operations
Segment Reporting Information [Line Items]
Operating revenues	310	759	885	1,901
Operating costs	482	1,221	1,712	4,979
Other income (expense)	279	787	946	948
Income tax expense (benefit)				4
Earnings (loss) before income taxes	(172)	(462)	(827)	(3,078)
Net earnings (loss)	(172)	(462)	(827)	(3,082)
Loss attributable to noncontrolling interest
Net earnings (loss) attributable to Signature Group Holdings, Inc.	(172)	(462)	(827)	(3,082)
Current assets	687		687		3,614
Total assets	1,268		1,268		4,264
Current liabilities	2,065		2,065		2,292
Total liabilities	8,815		8,815		9,792
Total
Segment Reporting Information [Line Items]
Operating costs	12,652	13,861	37,216	41,155
Other income (expense)	(3,022)	(123)	(7,404)	(275)
Earnings (loss) before income taxes	(5,866)	(2,688)	(10,462)	(7,739)
Income tax expense (benefit)	(7)	(60)	86	26
Loss attributable to noncontrolling interest
Net loss	(5,859)	(2,628)	(10,548)	(7,765)
Net loss attributable to Signature Group Holdings, Inc.	(5,859)	(2,628)	(10,548)	(7,765)
Current assets	93,967		93,967		76,113
Total assets	118,695		118,695		125,711
Current liabilities	9,850		9,850		14,013
Total liabilities	69,657		69,657		67,485
External Customer | Continuing Operations
Segment Reporting Information [Line Items]
Operating revenues	9,777	11,324	34,219	32,738
External Customer | Continuing Operations | Operating Segments | Wholesale Electrical Distribution
Segment Reporting Information [Line Items]
Operating revenues	10,230	10,203	28,054	27,107
External Customer | Continuing Operations | Operating Segments | Signature Special Situations
Segment Reporting Information [Line Items]
Operating revenues	(453)	1,121	6,165	5,631
External Customer | Discontinued Operations
Segment Reporting Information [Line Items]
Operating revenues	31	(28)	(61)	953
External Customer | Total
Segment Reporting Information [Line Items]
Operating revenues	9,808	11,296	34,158	33,691
Intersegment Eliminations | Continuing Operations | Operating Segments | Signature Special Situations
Segment Reporting Information [Line Items]
Operating revenues	102	102	303	304
Intersegment Eliminations | Continuing Operations | Corporate and Other
Segment Reporting Information [Line Items]
Operating revenues		270	316	680
Intersegment Eliminations | Continuing Operations | Eliminations
Segment Reporting Information [Line Items]
Operating revenues	$ (102)	$ (372)	$ (619)	$ (984)