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Investments (Number of Securities in an Unrealized Unrecognized Loss Position) (Details) - Available-for-sale Securities [Member] - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
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Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 415,506 | $ 516,259
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (6,108) | (3,379)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 185,335 | 230,770
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (5,434) | (4,359)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 600,841 | 747,029
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (11,542) | (7,738)
U.S. Government and Government Agencies [Member] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 11,519 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (137) | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 11,519 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (137) | 0
Foreign Government [Member] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 1,122 | 1,416
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (3) | (2)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 1,122 | 1,416
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (3) | (2)
Obligations of States and Political Subdivisions [Member] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 2,223 | 35,838
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (11) | (270)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 2,223 | 35,838
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (11) | (270)
Corporate Securities [Member] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 65,187 | 84,832
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (2,152) | (480)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 2,400 | 20,182
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (188) | (830)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 67,587 | 105,014
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (2,340) | (1,310)
Collateralized Loan Obligations and Other Asset-Backed Securities [Member] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 261,746 | 205,191
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (2,995) | (1,938)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 165,661 | 204,385
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (4,848) | (3,496)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 427,407 | 409,576
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (7,843) | (5,434)
Residential Mortgage Backed Securities [Member] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 18,227 | 126,089
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (194) | (425)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 1,181 | 5,375
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (7) | (30)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 19,408 | 131,464
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | (201) | (455)
Commercial Mortgage Backed Securities [Member] |  |
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 55,482 | 62,893
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss | (616) | (264)
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 16,093 | 828
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss | (391) | (3)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value | 71,575 | 63,721
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | $ (1,007) | $ (267)

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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer. + References No definition available. + Details
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27337-111563 + Details
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- Definition This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities. + References No definition available. + Details
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months. + References No definition available. + Details
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