Operating Results and Other Key Financial Measures of Operating Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Operating revenues	$ 14,866	$ 9,340	$ 24,440	$ 21,415
Operating costs	13,110	12,198	23,334	23,537
Other income (expense)	(3,614)	(261)	(5,048)	(313)
Earnings (loss) before income taxes	(1,858)	(3,119)	(3,942)	(2,435)
Income tax expense (benefit)	15	36	93	81
Net earnings (loss)	(1,924)	(3,890)	(4,690)	(5,136)
Net earnings (loss)	(1,873)	(3,155)	(4,035)	(2,516)
Net earnings (loss)	(51)	(735)	(655)	(2,620)
Loss attributable to noncontrolling interest
Net earnings (loss) attributable to Signature Group Holdings, Inc.	(51)	(735)	(655)	(2,620)
Net earnings (loss) attributable to Signature Group Holdings, Inc.	(1,924)	(3,890)	(4,690)	(5,136)
Current assets	97,219		97,219		76,113
Total assets	124,371		124,371		125,711
Current liabilities	12,928		12,928		14,013
Total liabilities	70,073		70,073		67,485
Discontinued Operations
Segment Reporting Information [Line Items]
Operating revenues	516	964	577	1,143
Operating costs	567	1,699	1,233	3,759
Other income (expense)	353	(56)	668	161
Earnings (loss) before income taxes	(51)	(735)	(656)	(2,616)
Income tax expense (benefit)			(1)	4
Net earnings (loss)	(51)	(735)	(655)	(2,620)
Loss attributable to noncontrolling interest
Net earnings (loss) attributable to Signature Group Holdings, Inc.	(51)	(735)		(2,620)
Current assets	2,750		2,750		3,614
Total assets	3,367		3,367		4,264
Net earnings (loss) attributable to Signature Group Holdings, Inc.			(655)
Current liabilities	2,096		2,096		2,292
Total liabilities	9,096		9,096		9,792
Discontinued Operations | External Customer
Segment Reporting Information [Line Items]
Operating revenues	163	1,020	(91)	982
Discontinued Operations | Intersegment Eliminations
Segment Reporting Information [Line Items]
Operating revenues
Continuing Operations
Segment Reporting Information [Line Items]
Operating costs	13,110	12,198	23,334	23,537
Other income (expense)	(3,614)	(261)	(5,048)	(313)
Earnings (loss) before income taxes	(1,858)	(3,119)	(3,942)	(2,435)
Income tax expense (benefit)	15	36	93	81
Net earnings (loss)	(1,873)	(3,155)	(4,035)	(2,516)
Loss attributable to noncontrolling interest		0
Current assets	94,469		94,469		72,499
Total assets	121,004		121,004		121,447
Net earnings (loss) attributable to Signature Group Holdings, Inc.	(1,873)	(3,155)	(4,035)	(2,516)
Current liabilities	10,832		10,832		11,721
Total liabilities	60,977		60,977		57,693
Continuing Operations | Operating Segments | Wholesale Electrical Distribution
Segment Reporting Information [Line Items]
Operating costs	7,788	7,760	14,877	14,436
Other income (expense)		(75)		(148)
Earnings (loss) before income taxes	1,664	1,227	2,946	2,321
Income tax expense (benefit)	641	489	1,150	927
Net earnings (loss)	1,023	738	1,796	1,394
Loss attributable to noncontrolling interest
Current assets	16,425		16,425		15,253
Total assets	38,140		38,140		37,667
Net earnings (loss) attributable to Signature Group Holdings, Inc.	1,023	738	1,796	1,394
Current liabilities	9,017		9,017		15,127
Total liabilities	24,688		24,688		26,012
Continuing Operations | Operating Segments | Signature Special Situations
Segment Reporting Information [Line Items]
Operating costs	128	303	408	481
Earnings (loss) before income taxes	5,387	76	6,410	4,231
Income tax expense (benefit)	2,035	13	2,498	32
Net earnings (loss)	3,352	63	3,912	4,199
Loss attributable to noncontrolling interest
Current assets	7,355		7,355		12,229
Total assets	16,807		16,807		43,230
Net earnings (loss) attributable to Signature Group Holdings, Inc.	3,352	63	3,912	4,199
Current liabilities	8		8		1,583
Total liabilities	3,907		3,907		23,539
Continuing Operations | Corporate and Other
Segment Reporting Information [Line Items]
Operating costs	5,370	4,501	8,566	9,232
Other income (expense)	(3,614)	(186)	(5,048)	(165)
Earnings (loss) before income taxes	(8,909)	(4,422)	(13,298)	(8,987)
Income tax expense (benefit)	(2,661)	(466)	(3,555)	(878)
Net earnings (loss)	(6,248)	(3,956)	(9,743)	(8,109)
Loss attributable to noncontrolling interest
Current assets	70,689		70,689		50,760
Total assets	80,485		80,485		72,758
Net earnings (loss) attributable to Signature Group Holdings, Inc.	(6,248)	(3,956)	(9,743)	(8,109)
Current liabilities	1,807		1,807		754
Total liabilities	46,810		46,810		40,350
Continuing Operations | Eliminations
Segment Reporting Information [Line Items]
Operating costs	(176)	(366)	(517)	(612)
Loss attributable to noncontrolling interest
Current assets					(5,743)
Total assets	(14,428)		(14,428)		(32,208)
Current liabilities					(5,743)
Total liabilities	(14,428)		(14,428)		(32,208)
Continuing Operations | External Customer
Segment Reporting Information [Line Items]
Operating revenues	14,866	9,340	24,440	21,415
Continuing Operations | External Customer | Operating Segments | Wholesale Electrical Distribution
Segment Reporting Information [Line Items]
Operating revenues	9,452	9,062	17,823	16,905
Continuing Operations | External Customer | Operating Segments | Signature Special Situations
Segment Reporting Information [Line Items]
Operating revenues	5,414	278	6,617	4,510
Continuing Operations | Intersegment Eliminations
Segment Reporting Information [Line Items]
Operating revenues	0	0		0
Continuing Operations | Intersegment Eliminations | Operating Segments | Signature Special Situations
Segment Reporting Information [Line Items]
Operating revenues	101	101	201	202
Continuing Operations | Intersegment Eliminations | Corporate and Other
Segment Reporting Information [Line Items]
Operating revenues	75	265	316	410
Continuing Operations | Intersegment Eliminations | Eliminations
Segment Reporting Information [Line Items]
Operating revenues	(176)	(366)	(517)	(612)
Total
Segment Reporting Information [Line Items]
Operating costs	13,677	13,897	24,567	27,296
Other income (expense)	(3,261)	(317)	(4,380)	(152)
Earnings (loss) before income taxes	(1,909)	(3,854)	(4,598)	(5,051)
Income tax expense (benefit)	15	36	92	85
Net earnings (loss)	(1,924)	(3,890)	(4,690)	(5,136)
Net earnings (loss) attributable to Signature Group Holdings, Inc.	(1,924)	(3,890)	(4,690)
Net earnings (loss) attributable to Signature Group Holdings, Inc.				(5,136)
Total | External Customer
Segment Reporting Information [Line Items]
Operating revenues	$ 15,029	$ 10,360	$ 24,349	$ 22,397