v2.4.1.9
Investments (Details 3) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Jun. 30, 2014
Investments [Line Items]        
Total assets $ 5,915us-gaap_Assets $ 6,885us-gaap_Assets    
Total liabilities 52us-gaap_Liabilities 33us-gaap_Liabilities    
Total shareholders’ equity 5,863us-gaap_StockholdersEquity 6,852us-gaap_StockholdersEquity 9,180us-gaap_StockholdersEquity  
Interlink Electronics [Member]        
Investments [Line Items]        
Current assets       5,566us-gaap_AssetsCurrent
/ dei_LegalEntityAxis
= bkfg_InterlinkElectronicsMember
Noncurrent assets       216us-gaap_AssetsNoncurrent
/ dei_LegalEntityAxis
= bkfg_InterlinkElectronicsMember
Total assets       5,782us-gaap_Assets
/ dei_LegalEntityAxis
= bkfg_InterlinkElectronicsMember
Current liabilities       826us-gaap_LiabilitiesCurrent
/ dei_LegalEntityAxis
= bkfg_InterlinkElectronicsMember
Other long-term liabilities       92us-gaap_OtherLiabilitiesNoncurrent
/ dei_LegalEntityAxis
= bkfg_InterlinkElectronicsMember
Total liabilities       918us-gaap_Liabilities
/ dei_LegalEntityAxis
= bkfg_InterlinkElectronicsMember
Total shareholders’ equity       $ 4,864us-gaap_StockholdersEquity
/ dei_LegalEntityAxis
= bkfg_InterlinkElectronicsMember