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Securities (Schedule of Available-for-sale Debt Securities) (Details) - USD ($) $ in Thousands | Sep. 30, 2019 | Dec. 31, 2018
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Schedule of Available-for-sale Debt Securities |  |
Total available-for-sale debt investment securities, Amortized Cost | $ 3,259,784 | $ 2,806,900
Gross Unrealized Gains | 32,319 | 5,714
Gross Unrealized Losses | (8,069) | (70,767)
Available-for-sale debt securities, Fair Value | 3,284,034 | 2,741,847
U.S. Treasury securities |  |
Schedule of Available-for-sale Debt Securities |  |
Total available-for-sale debt investment securities, Amortized Cost | 427,535 | 577,561
Gross Unrealized Gains | 0 | 153
Gross Unrealized Losses | (1,422) | (12,899)
Available-for-sale debt securities, Fair Value | 426,113 | 564,815
U.S. government agency and U.S. government sponsored enterprise debt securities |  |
Schedule of Available-for-sale Debt Securities |  |
Total available-for-sale debt investment securities, Amortized Cost | 688,529 | 219,485
Gross Unrealized Gains | 2,924 | 382
Gross Unrealized Losses | (85) | (2,694)
Available-for-sale debt securities, Fair Value | 691,368 | 217,173
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Commercial mortgage-backed securities |  |
Schedule of Available-for-sale Debt Securities |  |
Total available-for-sale debt investment securities, Amortized Cost | 539,957 | 420,486
Gross Unrealized Gains | 12,500 | 811
Gross Unrealized Losses | (2,664) | (12,694)
Available-for-sale debt securities, Fair Value | 549,793 | 408,603
U.S. government agency and U.S. government sponsored enterprise mortgage-backed securities - Residential mortgage-backed securities |  |
Schedule of Available-for-sale Debt Securities |  |
Total available-for-sale debt investment securities, Amortized Cost | 914,379 | 957,219
Gross Unrealized Gains | 11,914 | 4,026
Gross Unrealized Losses | (906) | (14,552)
Available-for-sale debt securities, Fair Value | 925,387 | 946,693
Municipal securities |  |
Schedule of Available-for-sale Debt Securities |  |
Total available-for-sale debt investment securities, Amortized Cost | 76,948 | 82,965
Gross Unrealized Gains | 1,218 | 87
Gross Unrealized Losses | (7) | (1,032)
Available-for-sale debt securities, Fair Value | 78,159 | 82,020
Non-agency commercial mortgage-backed securities |  |
Schedule of Available-for-sale Debt Securities |  |
Total available-for-sale debt investment securities, Amortized Cost | 67,518 | 25,826
Gross Unrealized Gains | 2,731 | 226
Gross Unrealized Losses | (6) | 0
Available-for-sale debt securities, Fair Value | 70,243 | 26,052
Non-agency residential mortgage-backed securities |  |
Schedule of Available-for-sale Debt Securities |  |
Total available-for-sale debt investment securities, Amortized Cost | 31,209 | 10,109
Gross Unrealized Gains | 425 | 7
Gross Unrealized Losses | (139) | (185)
Available-for-sale debt securities, Fair Value | 31,495 | 9,931
Corporate debt securities |  |
Schedule of Available-for-sale Debt Securities |  |
Total available-for-sale debt investment securities, Amortized Cost | 11,250 | 11,250
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | (228) | (381)
Available-for-sale debt securities, Fair Value | 11,022 | 10,869
Foreign bonds |  |
Schedule of Available-for-sale Debt Securities |  |
Total available-for-sale debt investment securities, Amortized Cost | 454,431 | 489,378
Gross Unrealized Gains | 607 | 0
Gross Unrealized Losses | (1,859) | (26,330)
Available-for-sale debt securities, Fair Value | 453,179 | 463,048
Asset-backed securities |  |
Schedule of Available-for-sale Debt Securities |  |
Total available-for-sale debt investment securities, Amortized Cost | 48,028 | 12,621
Gross Unrealized Gains | 0 | 22
Gross Unrealized Losses | (753) | 0
Available-for-sale debt securities, Fair Value | $ 47,275 | $ 12,643

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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
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