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Securities (Summary of Gross Unrealized Losses and Fair Value of the Investments with Unrealized Losses) (Details) - USD ($) $ in Thousands | Mar. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 Months Fair Value | $ 63,945 | $ 1,157,774
Less than 12 Months Unrealized Losses | (398) | (13,446)
12 Months or More Fair Value | 72,174 | 521,420
12 Months or More Unrealized Losses | (1,381) | (6,994)
Total Fair Value | 136,119 | 1,679,194
Total Unrealized Losses | (1,779) | (20,440)
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 Months Fair Value | 5,653 | 1,055,903
Less than 12 Months Unrealized Losses | (73) | (12,424)
12 Months or More Fair Value | 69,916 | 491,539
12 Months or More Unrealized Losses | (1,375) | (6,798)
Total Fair Value | 75,569 | 1,547,442
Total Unrealized Losses | (1,448) | (19,222)
Asset-backed Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 Months Fair Value | 15,105 | 89,508
Less than 12 Months Unrealized Losses | (44) | (880)
12 Months or More Fair Value | 626 | 6,799
12 Months or More Unrealized Losses | (3) | (109)
Total Fair Value | 15,731 | 96,307
Total Unrealized Losses | (47) | (989)
State and Municipal Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 Months Fair Value | 43,187 | 12,363
Less than 12 Months Unrealized Losses | (281) | (142)
12 Months or More Fair Value | 1,632 | 12,587
12 Months or More Unrealized Losses | (3) | (82)
Total Fair Value | 44,819 | 24,950
Total Unrealized Losses | $ (284) | (224)
U.S. Government and Government-Sponsored Enterprise Securities [Member] |  |
Debt Securities, Available-for-sale [Line Items] |  |
Less than 12 Months Fair Value |  | 0
Less than 12 Months Unrealized Losses |  | 0
12 Months or More Fair Value |  | 10,495
12 Months or More Unrealized Losses |  | (5)
Total Fair Value |  | 10,495
Total Unrealized Losses |  | $ (5)

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