v2.4.1.9
Investments (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Jun. 30, 2014
Jun. 30, 2013
Investments [Line Items]        
Total operating expenses $ 300us-gaap_OperatingExpenses $ 708us-gaap_OperatingExpenses    
Other income (734)us-gaap_OtherNonoperatingIncomeExpense (1,678)us-gaap_OtherNonoperatingIncomeExpense    
Provision (benefit) for income taxes 0us-gaap_IncomeTaxExpenseBenefit 0us-gaap_IncomeTaxExpenseBenefit    
Net loss (989)us-gaap_NetIncomeLoss (2,343)us-gaap_NetIncomeLoss    
Qualstar [Member]        
Investments [Line Items]        
Net revenues     10,941us-gaap_SalesRevenueNet
/ dei_LegalEntityAxis
= bkfg_QualstarMember
12,642us-gaap_SalesRevenueNet
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Cost of goods sold     8,350us-gaap_CostOfGoodsSold
/ dei_LegalEntityAxis
= bkfg_QualstarMember
9,187us-gaap_CostOfGoodsSold
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Gross profit     2,591us-gaap_GrossProfit
/ dei_LegalEntityAxis
= bkfg_QualstarMember
3,455us-gaap_GrossProfit
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Total operating expenses     8,239us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= bkfg_QualstarMember
(13,866)us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Loss from operations     (5,648)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= bkfg_QualstarMember
(10,411)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Other income     24us-gaap_OtherNonoperatingIncomeExpense
/ dei_LegalEntityAxis
= bkfg_QualstarMember
48us-gaap_OtherNonoperatingIncomeExpense
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Loss before income taxes     (5,624)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= bkfg_QualstarMember
(10,363)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Provision (benefit) for income taxes     0us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= bkfg_QualstarMember
 
Net loss     $ (5,624)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= bkfg_QualstarMember
$ (10,363)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= bkfg_QualstarMember