Securities - Summary of AFS Securities Portfolio (Details) - USD ($) $ in Thousands |
Mar. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Schedule Of Available For Sale Securities [Line Items] | ||
| Amortized cost | $ 503,674 | $ 518,491 |
| Gross Unrealized gains | 562 | 871 |
| Gross Unrealized losses | (10,253) | (9,784) |
| Estimated Fair Value | 493,983 | 509,578 |
| U.S. Treasury Securities | ||
| Schedule Of Available For Sale Securities [Line Items] | ||
| Amortized cost | 300 | 300 |
| Gross Unrealized losses | (2) | (3) |
| Estimated Fair Value | 298 | 297 |
| Agency Mortgage-backed Securities | ||
| Schedule Of Available For Sale Securities [Line Items] | ||
| Amortized cost | 461,954 | 476,163 |
| Gross Unrealized gains | 264 | 160 |
| Gross Unrealized losses | (7,794) | (7,414) |
| Estimated Fair Value | 454,424 | 468,909 |
| Beneficial interests in FHLMC securitization | ||
| Schedule Of Available For Sale Securities [Line Items] | ||
| Amortized cost | 41,420 | 42,028 |
| Gross Unrealized gains | 298 | 711 |
| Gross Unrealized losses | (2,457) | (2,367) |
| Estimated Fair Value | $ 39,261 | $ 40,372 |