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Investments (Tables) | 3 Months Ended
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Mar. 31, 2021
Schedule of Investments [Line Items] |
Schedule of Available-for-sale Securities |
March 31, 2021 |  |  |  |  |  |  |  |  |  |
($ in thousands) |  | Cost/ Amortized Cost |  | Allowance for Credit Losses |  | Unrealized Gains |  | Unrealized Losses |  | Fair Value
AFS fixed income securities: |  |  |  |  |  |  |  |  |  |
U.S. government and government agencies |  | $ | 134,725 |  |  | — |  |  | 3,653 |  |  | (2,104) |  |  | 136,274 |
Foreign government |  | 18,920 |  |  | (56) |  |  | 974 |  |  | (136) |  |  | 19,702 |
Obligations of states and political subdivisions |  | 1,140,442 |  |  | (201) |  |  | 74,212 |  |  | (360) |  |  | 1,214,093 |
Corporate securities |  | 2,239,066 |  |  | (6,166) |  |  | 122,761 |  |  | (9,870) |  |  | 2,345,791 |
Collateralized loan obligations ("CLO") and other asset-backed securities ("ABS") |  | 1,188,670 |  |  | (1,470) |  |  | 18,917 |  |  | (4,052) |  |  | 1,202,065 |
Residential mortgage-backed securities ("RMBS") |  | 906,266 |  |  | (864) |  |  | 43,367 |  |  | (1,229) |  |  | 947,540 |
Commercial mortgage-backed securities ("CMBS") |  | 624,988 |  |  | (24) |  |  | 33,590 |  |  | (2,378) |  |  | 656,176 |
Total AFS fixed income securities |  | $ | 6,253,077 |  |  | (8,781) |  |  | 297,474 |  |  | (20,129) |  |  | 6,521,641 |
December 31, 2020 |  |  |  |  |  |  |  |  |  |
($ in thousands) |  | Cost/ Amortized Cost |  | Allowance for Credit Losses |  | Unrealized Gains |  | Unrealized Losses |  | Fair Value
AFS fixed income securities: |  |  |  |  |  |  |  |  |  |
U.S. government and government agencies |  | $ | 110,038 |  |  | — |  |  | 6,239 |  |  | (137) |  |  | 116,140 |
Foreign government |  | 16,801 |  |  | (1) |  |  | 1,569 |  |  | (3) |  |  | 18,366 |
Obligations of states and political subdivisions |  | 1,159,588 |  |  | (4) |  |  | 87,564 |  |  | (11) |  |  | 1,247,137 |
Corporate securities |  | 2,152,203 |  |  | (2,782) |  |  | 180,971 |  |  | (2,340) |  |  | 2,328,052 |
CLO and other ABS |  | 1,014,820 |  |  | (592) |  |  | 20,166 |  |  | (7,843) |  |  | 1,026,551 |
RMBS |  | 999,485 |  |  | (561) |  |  | 53,065 |  |  | (201) |  |  | 1,051,788 |
CMBS |  | 620,582 |  |  | (29) |  |  | 48,348 |  |  | (1,007) |  |  | 667,894 |
Total AFS fixed income securities |  | $ | 6,073,517 |  |  | (3,969) |  |  | 397,922 |  |  | (11,542) |  |  | 6,455,928 |
Debt Securities, Available-for-sale, Allowance for Credit Loss [Table Text Block] |
Quarter ended March 31, 2021 |  |  |  |  |  |  |  |  |  |  |  |
($ in thousands) |  | Beginning Balance |  | Current Provision for Securities without Prior Allowance |  | Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities |  | Reductions for Securities Sold |  | Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period |  | Ending Balance
Foreign government |  | $ | 1 |  |  | 56 |  |  | (1) |  |  | — |  |  | — |  |  | 56 |
Obligations of states and political subdivisions |  | 4 |  |  | 186 |  |  | 11 |  |  | — |  |  | — |  |  | 201 |
Corporate securities |  | 2,782 |  |  | 4,058 |  |  | (527) |  |  | (147) |  |  | — |  |  | 6,166 |
CLO and other ABS |  | 592 |  |  | 1,001 |  |  | (106) |  |  | (17) |  |  | — |  |  | 1,470 |
RMBS |  | 561 |  |  | 356 |  |  | (39) |  |  | (14) |  |  | — |  |  | 864 |
CMBS |  | 29 |  |  | 10 |  |  | (15) |  |  | — |  |  | — |  |  | 24 |
Total AFS fixed income securities |  | $ | 3,969 |  |  | 5,667 |  |  | (677) |  |  | (178) |  |  | — |  |  | 8,781 |
Quarter ended March 31, 2020 |  |  |  |  |  |  |  |  |  |  |  |
($ in thousands) |  | Beginning Balance |  | Current Provision for Securities without Prior Allowance |  | Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirement) to Sell Securities |  | Reductions for Securities Sold |  | Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period |  | Ending Balance
Foreign government |  | $ | — |  |  | 21 |  |  | — |  |  | — |  |  | — |  |  | 21 |
Obligations of states and political subdivisions |  | — |  |  | 29 |  |  | — |  |  | — |  |  | — |  |  | 29 |
Corporate securities |  | — |  |  | 13,412 |  |  | — |  |  | — |  |  | — |  |  | 13,412 |
CLO and other ABS |  | — |  |  | 1,565 |  |  | — |  |  | — |  |  | — |  |  | 1,565 |
RMBS |  | — |  |  | 722 |  |  | — |  |  | — |  |  | — |  |  | 722 |
CMBS |  | — |  |  | 38 |  |  | — |  |  | — |  |  | — |  |  | 38 |
Total AFS fixed income securities |  | $ | — |  |  | 15,787 |  |  | — |  |  | — |  |  | — |  |  | 15,787 |
Schedule of Fair Value and Gross Pre-Tax Net Unrealized Loss of Securities by Length of Time, AFS |
March 31, 2021 |  | Less than 12 months |  | 12 months or longer |  | Total
($ in thousands) |  | Fair Value |  | Unrealized Losses |  | Fair Value |  | Unrealized Losses |  | Fair Value |  | Unrealized Losses
AFS fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |
U.S. government and government agencies |  | $ | 53,796 |  |  | (2,104) |  |  | — |  |  | — |  |  | 53,796 |  |  | (2,104) |
Foreign government |  | 3,313 |  |  | (136) |  |  | — |  |  | — |  |  | 3,313 |  |  | (136) |
Obligations of states and political subdivisions |  | 18,838 |  |  | (352) |  |  | 369 |  |  | (8) |  |  | 19,207 |  |  | (360) |
Corporate securities |  | 306,052 |  |  | (8,560) |  |  | 14,025 |  |  | (1,310) |  |  | 320,077 |  |  | (9,870) |
CLO and other ABS |  | 282,939 |  |  | (1,737) |  |  | 105,261 |  |  | (2,315) |  |  | 388,200 |  |  | (4,052) |
RMBS |  | 76,684 |  |  | (1,229) |  |  | — |  |  | — |  |  | 76,684 |  |  | (1,229) |
CMBS |  | 70,510 |  |  | (2,089) |  |  | 23,474 |  |  | (289) |  |  | 93,984 |  |  | (2,378) |
Total AFS fixed income securities |  | $ | 812,132 |  |  | (16,207) |  |  | 143,129 |  |  | (3,922) |  |  | 955,261 |  |  | (20,129) |
December 31, 2020 |  | Less than 12 months |  | 12 months or longer |  | Total
($ in thousands) |  | Fair Value |  | Unrealized Losses |  | Fair Value |  | Unrealized Losses |  | Fair Value |  | Unrealized Losses
AFS fixed income securities: |  |  |  |  |  |  |  |  |  |  |  |
U.S. government and government agencies |  | $ | 11,519 |  |  | (137) |  |  | — |  |  | — |  |  | 11,519 |  |  | (137) |
Foreign government |  | 1,122 |  |  | (3) |  |  | — |  |  | — |  |  | 1,122 |  |  | (3) |
Obligations of states and political subdivisions |  | 2,223 |  |  | (11) |  |  | — |  |  | — |  |  | 2,223 |  |  | (11) |
Corporate securities |  | 65,187 |  |  | (2,152) |  |  | 2,400 |  |  | (188) |  |  | 67,587 |  |  | (2,340) |
CLO and other ABS |  | 261,746 |  |  | (2,995) |  |  | 165,661 |  |  | (4,848) |  |  | 427,407 |  |  | (7,843) |
RMBS |  | 18,227 |  |  | (194) |  |  | 1,181 |  |  | (7) |  |  | 19,408 |  |  | (201) |
CMBS |  | 55,482 |  |  | (616) |  |  | 16,093 |  |  | (391) |  |  | 71,575 |  |  | (1,007) |
Total AFS fixed income securities |  | $ | 415,506 |  |  | (6,108) |  |  | 185,335 |  |  | (5,434) |  |  | 600,841 |  |  | (11,542) |
Schedule of Fixed Maturity Securities By Contractual Maturities |
|  | AFS |  | HTM
($ in thousands) |  | Fair Value |  | Carrying Value |  | Fair Value
Due in one year or less |  | $ | 453,772 |  |  | 1,057 |  |  | 1,065 |
Due after one year through five years |  | 3,400,223 |  |  | 14,433 |  |  | 15,325 |
Due after five years through 10 years |  | 2,043,563 |  |  | 8,854 |  |  | 8,814 |
Due after 10 years |  | 624,083 |  |  | — |  |  | — |
Total fixed income securities |  | $ | 6,521,641 |  |  | 24,344 |  |  | 25,204 |
Schedule of Other Investment Portfolio By Strategy And Remaining Commitment Amount and Maximum Exposure to Loss Associated With Each Strategy |
Other Investments |  | March 31, 2021 |  | December 31, 2020
($ in thousands) |  | Carrying Value |  | Remaining Commitment |  | Maximum Exposure to Loss 1 |  | Carrying Value |  | Remaining Commitment |  | Maximum Exposure to Loss 1
Alternative Investments |  |  |  |  |  |  |  |  |  |  |  |
Private equity |  | $ | 182,032 |  |  | 104,070 |  |  | 286,102 |  |  | 157,276 |  |  | 100,905 |  |  | 258,181 |
Private credit |  | 56,819 |  |  | 98,072 |  |  | 154,891 |  |  | 54,017 |  |  | 98,330 |  |  | 152,347 |
Real assets |  | 19,689 |  |  | 15,891 |  |  | 35,580 |  |  | 19,659 |  |  | 16,493 |  |  | 36,152 |
Total alternative investments |  | 258,540 |  |  | 218,033 |  |  | 476,573 |  |  | 230,952 |  |  | 215,728 |  |  | 446,680 |
Other securities |  | 31,613 |  |  | — |  |  | 31,613 |  |  | 35,370 |  |  | — |  |  | 35,370 |
Total other investments |  | $ | 290,153 |  |  | 218,033 |  |  | 508,186 |  |  | 266,322 |  |  | 215,728 |  |  | 482,050 |
1 The maximum exposure to loss includes both the carry value of these investments and the related remaining commitments. In addition, tax credits that have been previously recognized in Other securities are subject to the risk of recapture, which we do not consider significant.
Schedule of Aggregated Summarized Income Statement Financial Information For Partnerships In Our Alternative Investment Portfolio |
Income Statement Information |  | Quarter ended March 31, |  |
($ in millions) |  | 2021 |  | 2020 |  |  |  |
Net investment income |  | $ | 481.6 |  |  | 12.7 |  |  |  |  |
Realized gains |  | 776.0 |  |  | 164.8 |  |  |  |  |
Net change in unrealized appreciation |  | 4,630.8 |  |  | 1,204.0 |  |  |  |  |
Net income |  | $ | 5,888.4 |  |  | 1,381.5 |  |  |  |  |
Insurance Subsidiaries’ alternative investments income |  | $ | 20.2 |  |  | 6.3 |  |  |  |  |
Schedule of Securities Pledged As Collateral |
($ in millions) |  | FHLBI Collateral |  | FHLBNY Collateral |  |  |  | State and Regulatory Deposits |  | Total
U.S. government and government agencies |  | $ | — |  |  | — |  |  |  |  | 21.0 |  |  | 21.0 |
Obligations of states and political subdivisions |  | — |  |  | — |  |  |  |  | 5.0 |  |  | 5.0 |
RMBS |  | 93.7 |  |  | 155.5 |  |  |  |  | — |  |  | 249.2 |
CMBS |  | 6.9 |  |  | 35.1 |  |  |  |  | — |  |  | 42.0 |
Total pledged as collateral |  | $ | 100.6 |  |  | 190.6 |  |  |  |  | 26.0 |  |  | 317.2 |
Schedule of Pre-Tax Net Investment Income Earned |
|  | Quarter ended March 31, |  |
($ in thousands) |  | 2021 |  | 2020 |  |  |  |
Fixed income securities |  | $ | 52,823 |  |  | 50,253 |  |  |  |  |
Commercial mortgage loans ("CMLs") |  | 514 |  |  | 62 |  |  |  |  |
Equity securities |  | 2,488 |  |  | 1,552 |  |  |  |  |
Short-term investments |  | 85 |  |  | 1,166 |  |  |  |  |
Other investments |  | 17,433 |  |  | 6,342 |  |  |  |  |
Investment expenses |  | (3,627) |  |  | (3,408) |  |  |  |  |
Net investment income earned |  | $ | 69,716 |  |  | 55,967 |  |  |  |  |
Schedule of realized and unrealized gains (losses) on securities |
|  | Quarter ended March 31, |  |
($ in thousands) |  | 2021 |  | 2020 |  |  |  |
Gross gains on sales |  | $ | 3,676 |  |  | 5,676 |  |  |  |  |
Gross losses on sales |  | (4,471) |  |  | (1,576) |  |  |  |  |
Net realized gains (losses) on disposals |  | (795) |  |  | 4,100 |  |  |  |  |
Net unrealized gains (losses) on equity securities |  | 11,280 |  |  | (17,137) |  |  |  |  |
Net credit loss expense on fixed income securities, AFS |  | (4,997) |  |  | (15,787) |  |  |  |  |
Net credit loss expense on fixed income securities, HTM |  | (7) |  |  | — |  |  |  |  |
Net credit loss expense on CMLs |  | — |  |  | (240) |  |  |  |  |
Losses on securities for which we have the intent to sell |  | (362) |  |  | (15,602) |  |  |  |  |
Net realized and unrealized gains (losses) |  | $ | 5,119 |  |  | (44,666) |  |  |  |  |
Unrealized Gain (Loss) on Equity Securities |
|  | Quarter ended March 31, |  |
($ in thousands) |  | 2021 |  | 2020 |  |  |  |
Unrealized gains (losses) recognized in income on equity securities: |  |  |  |  |  |  |  |
On securities remaining in our portfolio at March 31, 2021 |  | $ | 10,097 |  |  | (17,140) |  |  |  |  |
On securities sold during period |  | 1,183 |  |  | 3 |  |  |  |  |
Total unrealized gains (losses) recognized in income on equity securities |  | $ | 11,280 |  |  | (17,137) |  |  |  |  |

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