v3.8.0.1

Investments - Schedule of Investments Reconciliation (Details) - USD ($) $ in Thousands | 6 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Jun. 30, 2017 | Dec. 31, 2016 | Sep. 30, 2017
Schedule of Investments [Abstract] |  |  |
Fair value of securities transferred from AFS to HTM | $ 391,934 | $ 155,538 |
AFS transferred to HTM securities, unrealized gain | $ 4,313 | 15,770 |
Schedule of Investments [Line Items] |  |  |
Fixed Maturities, available-for-sale, Original or amortized cost |  | 4,005,642 | $ 3,844,996
Fixed Maturities, available-for-sale, Gross unrealized gains |  | 50,759 | 71,850
Fixed Maturities, available-for-sale, Gross unrealized losses |  | (84,735) | (32,259)
Fixed Maturities, available-for-sale, Fair value |  | 3,971,666 | 3,884,587
Fixed Maturities, held-to-maturity, Original or amortized cost |  | 752,212 | 1,118,368
Fixed Maturities, held-to-maturity, Gross unrealized gains |  | 16,370 | 34,486
Fixed Maturities, held-to-maturity, Gross unrealized losses |  | (2,447) | (748)
Fixed Maturities, held-to-maturity, Fair value |  | 766,135 | 1,152,106
Other Investments, Original or amortized cost |  | 10,057 | 5,640
Other Investments, Gross unrealized gains |  | 3,003 | 1,401
Other Investments, Gross unrealized losses |  | 0 | 0
Other investments |  | 13,060 | 7,041
Total investments, Original or amortized cost |  | 4,767,911 | 4,969,004
Investments, Gross unrealized gains |  | 70,132 | 107,737
Investments, Gross unrealized losses |  | (87,182) | (33,007)
Total investments |  | 4,750,861 | 5,043,734
U.S. treasury bonds [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Fixed Maturities, available-for-sale, Original or amortized cost |  | 5,186 | 5,194
Fixed Maturities, available-for-sale, Gross unrealized gains |  | 238 | 150
Fixed Maturities, available-for-sale, Gross unrealized losses |  | (11) | (8)
Fixed Maturities, available-for-sale, Fair value |  | 5,413 | 5,336
U.S. agency bonds – mortgage-backed [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Fixed Maturities, available-for-sale, Original or amortized cost |  | 1,720,436 | 2,004,645
Fixed Maturities, available-for-sale, Gross unrealized gains |  | 12,867 | 14,208
Fixed Maturities, available-for-sale, Gross unrealized losses |  | (17,265) | (12,451)
Fixed Maturities, available-for-sale, Fair value |  | 1,716,038 | 2,006,402
U.S. agency bonds – other [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Fixed Maturities, available-for-sale, Original or amortized cost |  | 18,082 |
Fixed Maturities, available-for-sale, Gross unrealized gains |  | 20 |
Fixed Maturities, available-for-sale, Gross unrealized losses |  | 0 |
Fixed Maturities, available-for-sale, Fair value |  | 18,102 |
Non-U.S. government and supranational bonds [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Fixed Maturities, available-for-sale, Original or amortized cost |  | 35,158 | 33,392
Fixed Maturities, available-for-sale, Gross unrealized gains |  | 73 | 216
Fixed Maturities, available-for-sale, Gross unrealized losses |  | (5,297) | (2,012)
Fixed Maturities, available-for-sale, Fair value |  | 29,934 | 31,596
Asset-backed securities [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Fixed Maturities, available-for-sale, Original or amortized cost |  | 217,232 | 257,969
Fixed Maturities, available-for-sale, Gross unrealized gains |  | 3,713 | 4,456
Fixed Maturities, available-for-sale, Gross unrealized losses |  | (69) | (164)
Fixed Maturities, available-for-sale, Fair value |  | 220,876 | 262,261
Corporate bonds [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Fixed Maturities, available-for-sale, Original or amortized cost |  | 1,947,347 | 1,541,296
Fixed Maturities, available-for-sale, Gross unrealized gains |  | 30,951 | 52,717
Fixed Maturities, available-for-sale, Gross unrealized losses |  | (62,093) | (17,624)
Fixed Maturities, available-for-sale, Fair value |  | 1,916,205 | 1,576,389
Fixed Maturities, held-to-maturity, Original or amortized cost |  | 752,212 | 1,057,943
Fixed Maturities, held-to-maturity, Gross unrealized gains |  | 16,370 | 34,027
Fixed Maturities, held-to-maturity, Gross unrealized losses |  | (2,447) | (748)
Fixed Maturities, held-to-maturity, Fair value |  | 766,135 | 1,091,222
Municipal bonds [Member] |  |  |
Schedule of Investments [Line Items] |  |  |
Fixed Maturities, available-for-sale, Original or amortized cost |  | 62,201 | 2,500
Fixed Maturities, available-for-sale, Gross unrealized gains |  | 2,897 | 103
Fixed Maturities, available-for-sale, Gross unrealized losses |  | 0 | 0
Fixed Maturities, available-for-sale, Fair value |  | $ 65,098 | 2,603
Fixed Maturities, held-to-maturity, Original or amortized cost |  |  | 60,425
Fixed Maturities, held-to-maturity, Gross unrealized gains |  |  | 459
Fixed Maturities, held-to-maturity, Gross unrealized losses |  |  | 0
Fixed Maturities, held-to-maturity, Fair value |  |  | $ 60,884

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