v3.8.0.1
Securities - Summary of AFS Securities Portfolio (Details) - USD ($)
$ in Thousands
Sep. 30, 2017
Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]    
Amortized cost $ 475,889 $ 518,491
Gross Unrealized gains 2,253 871
Gross Unrealized losses (6,640) (9,784)
Estimated Fair Value 471,502 509,578
U.S. Treasury Securities    
Schedule Of Available For Sale Securities [Line Items]    
Amortized cost 499 300
Gross Unrealized losses (4) (3)
Estimated Fair Value 495 297
Agency Mortgage-backed Securities    
Schedule Of Available For Sale Securities [Line Items]    
Amortized cost 436,415 476,163
Gross Unrealized gains 497 160
Gross Unrealized losses (4,464) (7,414)
Estimated Fair Value 432,448 468,909
Beneficial interests in FHLMC securitization    
Schedule Of Available For Sale Securities [Line Items]    
Amortized cost 38,975 42,028
Gross Unrealized gains 1,756 711
Gross Unrealized losses (2,172) (2,367)
Estimated Fair Value $ 38,559 $ 40,372