Annual report pursuant to Section 13 and 15(d)

Notes Payable (NFS Forgivable Loans) (Details)

v3.8.0.1
Notes Payable (NFS Forgivable Loans) (Details)
12 Months Ended
Nov. 04, 2015
USD ($)
Nov. 04, 2011
USD ($)
installment
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Revolving Credit Facility          
Debt Instrument [Line Items]          
Amount outstanding     $ 0 $ 0  
NFS Forgivable Loans          
Debt Instrument [Line Items]          
Term   7 years      
Loans payable   $ 15,000,000      
Number of installments | installment   7      
Annual installment   $ 2,143,000      
Forgiveness, principal     2,143,000 2,143,000 $ 2,143,000
Forgiveness, interest     295,000 $ 408,000 $ 525,000
Secured loan securities value     91,975,000    
NFS Forgivable Loans | Minimum          
Debt Instrument [Line Items]          
Effective percentage   6.00%      
NFS Forgivable Loans | Maximum          
Debt Instrument [Line Items]          
Effective percentage   11.00%      
NFS Forgivable Loans, Amended          
Debt Instrument [Line Items]          
Forgiveness, principal $ 1,786,000        
Forgiveness, interest $ 94,000        
Frost Gamma Investment Trust | Revolving Credit Facility          
Debt Instrument [Line Items]          
Amount outstanding     $ 40,000,000