v3.8.0.1
Securities - Summary of AFS Securities Portfolio (Details) - USD ($)
$ in Thousands
Mar. 31, 2018
Dec. 31, 2017
Schedule Of Available For Sale Securities [Line Items]    
Amortized cost $ 527,703 $ 526,560
Gross Unrealized gains 2,027 2,098
Gross Unrealized losses (16,663) (9,294)
Estimated Fair Value 513,067 519,364
U.S. Treasury Securities    
Schedule Of Available For Sale Securities [Line Items]    
Amortized cost 499 499
Gross Unrealized losses (6) (6)
Estimated Fair Value 493 493
Agency Mortgage-backed Securities    
Schedule Of Available For Sale Securities [Line Items]    
Amortized cost 453,596 471,131
Gross Unrealized gains   287
Gross Unrealized losses (14,728) (7,399)
Estimated Fair Value 438,868 464,019
Corporate Bonds    
Schedule Of Available For Sale Securities [Line Items]    
Amortized cost 39,000 35,930
Gross Unrealized gains 100 1,811
Gross Unrealized losses   (1,889)
Estimated Fair Value 39,100 35,852
Beneficial interest - FHLMC securitization    
Schedule Of Available For Sale Securities [Line Items]    
Amortized cost 34,608 19,000
Gross Unrealized gains 1,927  
Gross Unrealized losses (1,929)  
Estimated Fair Value $ 34,606 $ 19,000