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Investments (Fair Value and Gross Pre-Tax Net Unrealized Unrecognized Loss of Securities By Length of Time) (Details) - USD ($) $ in Thousands | Jun. 30, 2017 | Dec. 31, 2016
--- | --- | ---
AFS Fair Value, Less than 12 months |  | $ 589,841 | $ 1,358,111
AFS Unrealized Losses, Less than 12 months | [1] | (3,903) | (15,651)
AFS Fair Value, 12 months or longer |  | 2,980 | 15,626
AFS Unrealized Losses, 12 months or longer | [1] | (13) | (406)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value |  | 592,821 | 1,373,737
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | [1] | (3,916) | (16,057)
AFS Fixed Income Securities [Member] |  |  |
AFS Fair Value, Less than 12 months |  | 571,418 | 1,340,672
AFS Unrealized Losses, Less than 12 months | [1] | (2,916) | (14,991)
AFS Fair Value, 12 months or longer |  | 2,980 | 15,626
AFS Unrealized Losses, 12 months or longer | [1] | (13) | (406)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value |  | 574,398 | 1,356,298
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | [1] | (2,929) | (15,397)
AFS Fixed Income Securities [Member] | U.S. Government and Government Agencies [Member] |  |  |
AFS Fair Value, Less than 12 months |  | 12,670 | 6,419
AFS Unrealized Losses, Less than 12 months | [1] | (32) | (36)
AFS Fair Value, 12 months or longer |  | 0 | 0
AFS Unrealized Losses, 12 months or longer | [1] | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value |  | 12,670 | 6,419
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | [1] | (32) | (36)
AFS Fixed Income Securities [Member] | Foreign Government [Member] |  |  |
AFS Fair Value, Less than 12 months |  |  | 13,075
AFS Unrealized Losses, Less than 12 months | [1] |  | (16)
AFS Fair Value, 12 months or longer |  |  | 0
AFS Unrealized Losses, 12 months or longer | [1] |  | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value |  |  | 13,075
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | [1] |  | (16)
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member] |  |  |
AFS Fair Value, Less than 12 months |  | 107,387 | 306,509
AFS Unrealized Losses, Less than 12 months | [1] | (1,086) | (5,304)
AFS Fair Value, 12 months or longer |  | 0 | 0
AFS Unrealized Losses, 12 months or longer | [1] | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value |  | 107,387 | 306,509
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | [1] | (1,086) | (5,304)
AFS Fixed Income Securities [Member] | Corporate Securities [Member] |  |  |
AFS Fair Value, Less than 12 months |  | 72,991 | 462,902
AFS Unrealized Losses, Less than 12 months | [1] | (517) | (5,771)
AFS Fair Value, 12 months or longer |  | 2,531 | 4,913
AFS Unrealized Losses, 12 months or longer | [1] | (7) | (89)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value |  | 75,522 | 467,815
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | [1] | (524) | (5,860)
AFS Fixed Income Securities [Member] | Collateralized Loan Obligations and Other Asset Backed Securities [Member] |  |  |
AFS Fair Value, Less than 12 months |  | 156,406 | 189,795
AFS Unrealized Losses, Less than 12 months | [1] | (178) | (354)
AFS Fair Value, 12 months or longer |  | 0 | 319
AFS Unrealized Losses, 12 months or longer | [1] | 0 | (1)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value |  | 156,406 | 190,114
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | [1] | (178) | (355)
AFS Fixed Income Securities [Member] | Commercial Mortgage Backed Securities [Member] |  |  |
AFS Fair Value, Less than 12 months |  | 42,671 | 82,492
AFS Unrealized Losses, Less than 12 months | [1] | (243) | (1,021)
AFS Fair Value, 12 months or longer |  | 0 | 1,645
AFS Unrealized Losses, 12 months or longer | [1] | 0 | (7)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value |  | 42,671 | 84,137
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | [1] | (243) | (1,028)
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member] |  |  |
AFS Fair Value, Less than 12 months |  | 179,293 | 279,480
AFS Unrealized Losses, Less than 12 months | [1] | (860) | (2,489)
AFS Fair Value, 12 months or longer |  | 449 | 8,749
AFS Unrealized Losses, 12 months or longer | [1] | (6) | (309)
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value |  | 179,742 | 288,229
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | [1] | (866) | (2,798)
Equity Securities [Member] |  |  |
AFS Fair Value, Less than 12 months |  | 18,423 | 17,439
AFS Unrealized Losses, Less than 12 months | [1] | (987) | (660)
AFS Fair Value, 12 months or longer |  | 0 | 0
AFS Unrealized Losses, 12 months or longer | [1] | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value |  | 18,423 | 17,439
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | [1] | (987) | (660)
Equity Securities [Member] | Common Stock [Member] |  |  |
AFS Fair Value, Less than 12 months |  | 18,423 | 11,271
AFS Unrealized Losses, Less than 12 months | [1] | (987) | (305)
AFS Fair Value, 12 months or longer |  | 0 | 0
AFS Unrealized Losses, 12 months or longer | [1] | 0 | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value |  | 18,423 | 11,271
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | [1] | $ (987) | (305)
Equity Securities [Member] | Preferred Stock [Member] |  |  |
AFS Fair Value, Less than 12 months |  |  | 6,168
AFS Unrealized Losses, Less than 12 months | [1] |  | (355)
AFS Fair Value, 12 months or longer |  |  | 0
AFS Unrealized Losses, 12 months or longer | [1] |  | 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value |  |  | 6,168
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss | [1] |  | $ (355)
[1] | Gross unrealized losses include non-OTTI unrealized amounts and OTTI losses recognized in AOCI.

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