v2.4.1.9
Investments (Details 1) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Jun. 30, 2014
Jun. 30, 2013
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    
Qualstar [Member]          
Investments [Line Items]          
Current assets       12,055us-gaap_AssetsCurrent
/ dei_LegalEntityAxis
= bkfg_QualstarMember
14,046us-gaap_AssetsCurrent
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Noncurrent assets       730us-gaap_AssetsNoncurrent
/ dei_LegalEntityAxis
= bkfg_QualstarMember
6,161us-gaap_AssetsNoncurrent
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Total assets       12,785us-gaap_Assets
/ dei_LegalEntityAxis
= bkfg_QualstarMember
20,207us-gaap_Assets
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Current liabilities       3,645us-gaap_LiabilitiesCurrent
/ dei_LegalEntityAxis
= bkfg_QualstarMember
5,445us-gaap_LiabilitiesCurrent
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Other long-term liabilities       17us-gaap_OtherLiabilitiesNoncurrent
/ dei_LegalEntityAxis
= bkfg_QualstarMember
17us-gaap_OtherLiabilitiesNoncurrent
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Total liabilities       3,662us-gaap_Liabilities
/ dei_LegalEntityAxis
= bkfg_QualstarMember
5,462us-gaap_Liabilities
/ dei_LegalEntityAxis
= bkfg_QualstarMember
Total shareholders’ equity       $ 9,123us-gaap_StockholdersEquity
/ dei_LegalEntityAxis
= bkfg_QualstarMember
$ 14,745us-gaap_StockholdersEquity
/ dei_LegalEntityAxis
= bkfg_QualstarMember