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Investment Securities and Equity Securities with Readily Determinable Fair Values (Details) - USD ($) $ in Thousands | Jun. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Held-to-maturity securities |  |
Amortized cost | $ 3,400 | $ 2,400
Estimated fair value | 3,400 | 2,400
Carrying Value | 3,400 | 2,400
Available-for-sale securities |  |
Amortized cost | 3,045,135 | 3,376,070
Available for sale debt securities | 3,097,734 | 3,378,923
Total Amortized cost | 3,045,135 | 3,376,070
Total Gross unrealized gains | 56,229 | 19,467
Total Gross unrealized losses | 3,630 | 16,614
Assets/liabilities measured at fair value |  |
Available-for-sale securities |  |
Available for sale debt securities and equity securities | 3,097,734 | 3,378,923
Carrying Value |  |
Available-for-sale securities |  |
Available for sale debt securities and equity securities | 3,097,734 | 3,378,923
Residential mortgage-backed securities |  |
Available-for-sale securities |  |
Amortized cost | 2,973,842 | 3,285,623
Gross unrealized gains | 53,188 | 16,534
Gross unrealized losses | (3,617) | (16,609)
Residential mortgage-backed securities | Assets/liabilities measured at fair value |  |
Available-for-sale securities |  |
Available for sale debt securities | 3,023,413 | 3,285,548
Residential mortgage-backed securities | Carrying Value |  |
Available-for-sale securities |  |
Available for sale debt securities | 3,023,413 | 3,285,548
Mortgage-backed securities by Ginnie Mae |  |
Available-for-sale securities |  |
Available for sale debt securities | 506,404 | 521,247
Mortgage-backed securities by Fannie Mae and Freddie Mac |  |
Available-for-sale securities |  |
Available for sale debt securities | 2,517,009 | 2,714,301
Obligations of states and political subdivisions |  |
Available-for-sale securities |  |
Amortized cost | 71,293 | 90,447
Gross unrealized gains | 3,041 | 2,933
Gross unrealized losses | (13) | (5)
Obligations of states and political subdivisions | Assets/liabilities measured at fair value |  |
Available-for-sale securities |  |
Available for sale debt securities | 74,321 | 93,375
Obligations of states and political subdivisions | Carrying Value |  |
Available-for-sale securities |  |
Available for sale debt securities | 74,321 | 93,375
Other securities |  |
Held-to-maturity securities |  |
Amortized cost | 3,400 | 2,400
Estimated fair value | 3,400 | 2,400
Carrying Value | $ 3,400 | $ 2,400

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