v3.7.0.1
Borrowings - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2017
Dec. 31, 2016
Apr. 30, 2017
Jan. 31, 2017
Debt Instrument [Line Items]        
Overnight FHLB advances $ 582.0 $ 1.3    
FHLB advances interest rates       0.56%
FHLB, average balance of overnight borrowings 632.2 $ 507.0    
FFI        
Debt Instrument [Line Items]        
Long-term line of credit 20.0      
Revolving Credit Facility        
Debt Instrument [Line Items]        
Line of credit $ 25.0      
Line of credit maturity period 5 years      
Revolving Credit Facility | 90 Day LIBOR        
Debt Instrument [Line Items]        
Debt instrument basis point rate 3.50%      
Subsequent Event        
Debt Instrument [Line Items]        
FHLB advances interest rates     0.80%