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Investment Securities Available for Sale (Schedule of Gross Unrealized Losses on Investment Securities and Fair Value) (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 Months, Fair Value | $ 1,651,051 | $ 891,914
Less than 12 Months, Gross Unrealized Losses | (11,393) | (2,468)
12 Months or Longer, Fair Value | 0 | 5,309
12 Months or Longer, Gross Unrealized Losses | 0 | (38)
Total, Fair Value | 1,651,051 | 897,223
Total, Gross Unrealized Losses | (11,393) | (2,506)
U.S. Government agency securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 Months, Fair Value | 48,921 |
Less than 12 Months, Gross Unrealized Losses | (426) |
12 Months or Longer, Fair Value | 0 |
12 Months or Longer, Gross Unrealized Losses | 0 |
Total, Fair Value | 48,921 |
Total, Gross Unrealized Losses | (426) |
Mortgage-backed securities issued by U.S. Government agencies |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 Months, Fair Value | 800,908 | 19,543
Less than 12 Months, Gross Unrealized Losses | (6,079) | (70)
12 Months or Longer, Fair Value | 0 | 355
12 Months or Longer, Gross Unrealized Losses | 0 | (2)
Total, Fair Value | 800,908 | 19,898
Total, Gross Unrealized Losses | (6,079) | (72)
Mortgage-backed securities issued by U.S. Government sponsored enterprises |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 Months, Fair Value | 180,899 | 768,040
Less than 12 Months, Gross Unrealized Losses | (276) | (2,076)
12 Months or Longer, Fair Value | 0 | 0
12 Months or Longer, Gross Unrealized Losses | 0 | 0
Total, Fair Value | 180,899 | 768,040
Total, Gross Unrealized Losses | (276) | (2,076)
Collateralized mortgage obligations issued by U.S. Government agencies or sponsored enterprises |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 Months, Fair Value | 609,208 | 57,670
Less than 12 Months, Gross Unrealized Losses | (4,222) | (204)
12 Months or Longer, Fair Value | 0 | 0
12 Months or Longer, Gross Unrealized Losses | 0 | 0
Total, Fair Value | 609,208 | 57,670
Total, Gross Unrealized Losses | (4,222) | (204)
Asset-backed securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 Months, Fair Value |  | 37,156
Less than 12 Months, Gross Unrealized Losses |  | (116)
12 Months or Longer, Fair Value |  | 4,954
12 Months or Longer, Gross Unrealized Losses |  | (36)
Total, Fair Value |  | 42,110
Total, Gross Unrealized Losses |  | (152)
Corporate debt securities and other debt securities |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 Months, Fair Value | 11,115 | 9,505
Less than 12 Months, Gross Unrealized Losses | (390) | (2)
12 Months or Longer, Fair Value | 0 | 0
12 Months or Longer, Gross Unrealized Losses | 0 | 0
Total, Fair Value | 11,115 | 9,505
Total, Gross Unrealized Losses | $ (390) | $ (2)

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