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Investment Securities and Equity Securities with Readily Determinable Fair Values (Details) - USD ($) | Jun. 30, 2018 | Dec. 31, 2017
--- | --- | ---
Held-to-maturity securities |  |
Amortized cost | $ 2,400,000 | $ 2,400,000
Estimated fair value | 2,400,000 | 2,400,000
Carrying Value | 2,400,000 | 2,400,000
Available-for-sale securities |  |
Amortized cost, Available-for-sale securities | 3,822,194,000 | 4,196,263,000
Gross Unrealized Gains | 14,004,000 |
Gross Unrealized Losses | (115,632,000) |
Available for sale debt securities | 3,720,566,000 | 4,124,185,000
Equity Securities | 27,054,000 | 27,885,000
Total Amortized cost |  | 4,196,263,000
Total Gross unrealized gains |  | 22,274,000
Total Gross unrealized losses |  | 66,467,000
Assets/liabilities measured at fair value |  |
Available-for-sale securities |  |
Available for sale debt securities | 3,720,566,000 |
Available for sale debt securities and equity securities |  | 4,152,070,000
Carrying Value |  |
Available-for-sale securities |  |
Available for sale debt securities | 3,720,566,000 |
Available for sale debt securities and equity securities |  | 4,152,070,000
Residential mortgage-backed securities |  |
Available-for-sale securities |  |
Amortized cost, Available-for-sale securities | 3,615,831,000 | 3,943,092,000
Gross Unrealized Gains | 9,299,000 | 14,110,000
Gross Unrealized Losses | (115,487,000) | (65,969,000)
Residential mortgage-backed securities | Assets/liabilities measured at fair value |  |
Available-for-sale securities |  |
Available for sale debt securities | 3,509,643,000 | 3,891,233,000
Residential mortgage-backed securities | Carrying Value |  |
Available-for-sale securities |  |
Available for sale debt securities | 3,509,643,000 | 3,891,233,000
Mortgage-backed securities by Ginnie Mae |  |
Available-for-sale securities |  |
Available for sale debt securities | 571,385,000 | 654,063,000
Mortgage-backed securities by Fannie Mae and Freddie Mac |  |
Available-for-sale securities |  |
Available for sale debt securities | 2,938,258,000 | 3,237,170,000
Obligations of states and political subdivisions |  |
Available-for-sale securities |  |
Amortized cost, Available-for-sale securities | 206,363,000 | 225,096,000
Gross Unrealized Gains | 4,705,000 | 7,871,000
Gross Unrealized Losses | (145,000) | (16,000)
Obligations of states and political subdivisions | Assets/liabilities measured at fair value |  |
Available-for-sale securities |  |
Available for sale debt securities | 210,923,000 | 232,951,000
Obligations of states and political subdivisions | Carrying Value |  |
Available-for-sale securities |  |
Available for sale debt securities | 210,923,000 | 232,951,000
Other securities |  |
Held-to-maturity securities |  |
Amortized cost | 2,400,000 | 2,400,000
Estimated fair value | 2,400,000 | 2,400,000
Carrying Value | $ 2,400,000 | 2,400,000
Equity securities |  |
Available-for-sale securities |  |
Gross Unrealized Gains |  | 293,000
Amortized Cost, Equity securities |  | 28,075,000
Gross Unrealized Losses, Equity securities |  | (482,000)
Equity securities | Assets/liabilities measured at fair value |  |
Available-for-sale securities |  |
Equity Securities |  | 27,886,000
Equity securities | Carrying Value |  |
Available-for-sale securities |  |
Equity Securities |  | $ 27,886,000

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