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Investments (Tables) | 12 Months Ended
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Dec. 31, 2021
Investment [Line Items] |
Schedule of Unrealized Gains (Losses) On Investments |
($ in thousands) |  | 2021 |  | 2020 |  | 2019
AFS securities: |  |  |  |  |  |
Fixed income securities |  | $ | 228,947 |  |  | 386,380 |  |  | 215,634 |
Total AFS securities |  | 228,947 |  |  | 386,380 |  |  | 215,634 |
HTM securities: |  |  |  |  |  |
Fixed income securities |  | (4) |  |  | 7 |  |  | 31 |
Total HTM securities |  | (4) |  |  | 7 |  |  | 31 |
Short-term securities |  | 20 |  |  | 6 |  |  | 23 |
Total net unrealized gains |  | 228,963 |  |  | 386,393 |  |  | 215,688 |
Deferred income tax |  | (48,082) |  |  | (81,142) |  |  | (45,294) |
Net unrealized gains, net of deferred income tax |  | 180,881 |  |  | 305,251 |  |  | 170,394 |
Increase (decrease) in net unrealized gains in OCI, net of deferred income tax |  | $ | (124,370) |  |  | 134,857 |  |  | 168,505 |
Schedule of Available For Sale Securities |
December 31, 2021 |  |  |  |  |  |  |  |  |  |
|  | Cost/ |  |  |  |  |  |  |  |
|  | Amortized |  | Allowance for |  | Unrealized |  | Unrealized |  | Fair
($ in thousands) |  | Cost |  | Credit Losses |  | Gains |  | Losses |  | Value
AFS fixed income securities: |  |  |  |  |  |  |  |  |  |
U.S. government and government agencies |  | $ | 127,974 |  |  | — |  |  | 3,629 |  |  | (1,145) |  |  | 130,458 |
Foreign government |  | 15,420 |  |  | (46) |  |  | 609 |  |  | (123) |  |  | 15,860 |
Obligations of states and political subdivisions |  | 1,121,422 |  |  | (137) |  |  | 68,258 |  |  | (235) |  |  | 1,189,308 |
Corporate securities |  | 2,478,348 |  |  | (6,682) |  |  | 106,890 |  |  | (4,953) |  |  | 2,573,603 |
CLO and other ABS |  | 1,343,687 |  |  | (939) |  |  | 14,350 |  |  | (6,284) |  |  | 1,350,814 |
RMBS |  | 756,280 |  |  | (1,909) |  |  | 24,813 |  |  | (2,932) |  |  | 776,252 |
CMBS |  | 647,622 |  |  | (11) |  |  | 27,752 |  |  | (1,682) |  |  | 673,681 |
Total AFS fixed income securities |  | $ | 6,490,753 |  |  | (9,724) |  |  | 246,301 |  |  | (17,354) |  |  | 6,709,976 |
December 31, 2020 |  |  |  |  |  |  |  |  |  |
|  | Cost/ |  |  |  |  |  |  |  |
|  | Amortized |  | Allowance for |  | Unrealized |  | Unrealized |  | Fair
($ in thousands) |  | Cost |  | Credit Losses |  | Gains |  | Losses |  | 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 |
Schedule of debt securities, available-for-sale, allowance for credit losses |
2021 | Beginning Balance |  | Current Provisions for Securities without Prior Allowance |  | Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirements) to Sell Securities |  | Reductions for Securities Sold |  | Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period |  | Ending Balance
($ in thousands) |  |  |  |  |
Foreign Government | $ | 1 |  |  | 46 |  |  | (1) |  |  | — |  |  | — |  |  | 46 |
Obligations of states and political subdivisons | 4 |  |  | 122 |  |  | 11 |  |  | — |  |  | — |  |  | 137 |
Corporate Securities | 2,782 |  |  | 5,785 |  |  | (992) |  |  | (723) |  |  | (170) |  |  | 6,682 |
CLO and other ABS | 592 |  |  | 579 |  |  | (211) |  |  | (21) |  |  | — |  |  | 939 |
RMBS | 561 |  |  | 1,593 |  |  | (63) |  |  | (182) |  |  | — |  |  | 1,909 |
CMBS | 29 |  |  | 10 |  |  | (28) |  |  | — |  |  | — |  |  | 11 |
Total AFS fixed income securities | $ | 3,969 |  |  | 8,135 |  |  | (1,284) |  |  | (926) |  |  | (170) |  |  | 9,724 |
2020 | Beginning Balance |  | Current Provisions for Securities without Prior Allowance |  | Increase (Decrease) on Securities with Prior Allowance, excluding intent (or Requirements) to Sell Securities |  | Reductions for Securities Sold |  | Reductions for Securities Identified as Intent (or Requirement) to Sell during the Period |  | Ending Balance
($ in thousands) |  |  |  |  |
Foreign Government | $ | — |  |  | 19 |  |  | — |  |  | (18) |  |  | — |  |  | 1 |
Obligations of states and political subdivisons | — |  |  | 4 |  |  | — |  |  | — |  |  | — |  |  | 4 |
Corporate Securities | — |  |  | 3,645 |  |  | — |  |  | (781) |  |  | (82) |  |  | 2,782 |
CLO and other ABS | — |  |  | 722 |  |  | — |  |  | (113) |  |  | (17) |  |  | 592 |
RMBS | — |  |  | 623 |  |  | — |  |  | (62) |  |  | — |  |  | 561 |
CMBS | — |  |  | 29 |  |  | — |  |  | — |  |  | — |  |  | 29 |
Total AFS fixed income securities | $ | — |  |  | 5,042 |  |  | — |  |  | (974) |  |  | (99) |  |  | 3,969 |
Schedule of Fair Value and Gross Pre-Tax Net Unrealized/Unrecognized Loss of Securities by Length of Time |
December 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 |  | $ | 34,857 |  |  | (746) |  |  | 7,827 |  |  | (399) |  |  | 42,684 |  |  | (1,145) |
Foreign government |  | 2,000 |  |  | (84) |  |  | 1,061 |  |  | (39) |  |  | 3,061 |  |  | (123) |
Obligations of states and political subdivisions |  | 25,837 |  |  | (235) |  |  | — |  |  | — |  |  | 25,837 |  |  | (235) |
Corporate securities |  | 300,549 |  |  | (4,903) |  |  | 2,520 |  |  | (50) |  |  | 303,069 |  |  | (4,953) |
CLO and other ABS |  | 663,976 |  |  | (4,934) |  |  | 53,368 |  |  | (1,350) |  |  | 717,344 |  |  | (6,284) |
RMBS |  | 236,010 |  |  | (2,931) |  |  | 20 |  |  | (1) |  |  | 236,030 |  |  | (2,932) |
CMBS |  | 112,899 |  |  | (1,016) |  |  | 20,326 |  |  | (666) |  |  | 133,225 |  |  | (1,682) |
Total AFS fixed income securities |  | $ | 1,376,128 |  |  | (14,849) |  |  | 85,122 |  |  | (2,505) |  |  | 1,461,250 |  |  | (17,354) |
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 Investments Classified by Contractual Maturity Date |
|  | AFS |  | HTM
($ in thousands) |  | Fair Value |  | Carrying Value |  | Fair Value
Due in one year or less |  | $ | 500,579 |  |  | 1,384 |  |  | 1,401 |
Due after one year through five years |  | 3,182,282 |  |  | 11,811 |  |  | 12,493 |
Due after five years through 10 years |  | 2,316,389 |  |  | 15,590 |  |  | 15,566 |
Due after 10 years |  | 710,726 |  |  | — |  |  | — |
Total fixed income securities |  | $ | 6,709,976 |  |  | 28,785 |  |  | 29,460 |
Schedule of Other Investment Portfolio by Strategy and the Remaining Commitment Amount Associated With Each Strategy |
Other Investments |  | December 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 |  | $ | 273,070 |  |  | 99,734 |  |  | 372,804 |  |  | 157,276 |  |  | 100,905 |  |  | 258,181 |
Private credit |  | 63,138 |  |  | 92,674 |  |  | 155,812 |  |  | 54,017 |  |  | 98,330 |  |  | 152,347 |
Real assets |  | 23,524 |  |  | 22,579 |  |  | 46,103 |  |  | 19,659 |  |  | 16,493 |  |  | 36,152 |
Total alternative investments |  | 359,732 |  |  | 214,987 |  |  | 574,719 |  |  | 230,952 |  |  | 215,728 |  |  | 446,680 |
Other securities |  | 49,300 |  |  | — |  |  | 49,300 |  |  | 35,370 |  |  | — |  |  | 35,370 |
Total other investments |  | $ | 409,032 |  |  | 214,987 |  |  | 624,019 |  |  | 266,322 |  |  | 215,728 |  |  | 482,050 |
Schedule of Aggregated Summarized Balance Sheet Financial Information For Partnerships In Our Alternative Investment Portfolio |
Balance Sheet Information |  |  |  |
December 31, |  |  |  |
($ in millions) |  | 2021 |  | 2020
Investments |  | $ | 107,347 |  |  | 55,145 |
Total assets |  | 112,232 |  |  | 58,819 |
Total liabilities |  | 12,371 |  |  | 6,744 |
Total partners’ capital |  | 99,861 |  |  | 52,075 |
Schedule of Aggregated Summarized Income Statement Financial Information For Partnerships In Our Alternative Investment Portfolio |
Income Statement Information |  |  |  |  |  |
12 months ended September 30, |  |  |  |  |  |
($ in millions) |  | 2021 |  | 2020 |  | 2019
Net investment (loss) income |  | $ | 653 |  |  | (26) |  |  | (8) |
Realized gains |  | 6,121 |  |  | 1,452 |  |  | 695 |
Net change in unrealized appreciation |  | 26,877 |  |  | 4,898 |  |  | 5,543 |
Net income before tax |  | $ | 33,651 |  |  | 6,324 |  |  | 6,230 |
Alternative investment income included in "Net investment income earned" on our Consolidated Statements of Income |  | 117.7 |  |  | 26.5 |  |  | 17.9 |
Schedule Of Securities Pledged As Collateral |
($ in millions) |  | FHLBI Collateral |  | FHLBNY Collateral |  | State and Regulatory Deposits |  | Total
U.S. government and government agencies |  | $ | — |  |  | — |  |  | 22.3 |  |  | 22.3 |
Obligations of states and political subdivisions |  | — |  |  | — |  |  | 4.0 |  |  | 4.0 |
RMBS |  | 62.4 |  |  | 40.4 |  |  | — |  |  | 102.8 |
CMBS |  | 6.3 |  |  | 14.1 |  |  | — |  |  | 20.4 |
Total pledged as collateral |  | $ | 68.7 |  |  | 54.5 |  |  | 26.3 |  |  | 149.5 |
Schedule of Components of Pre-Tax Net Investment Income Earned |
($ in thousands) |  | 2021 |  | 2020 |  | 2019
Fixed income securities |  | $ | 209,709 |  |  | 203,926 |  |  | 203,255 |
CMLs |  | 2,743 |  |  | 844 |  |  | — |
Equity securities |  | 15,920 |  |  | 9,286 |  |  | 6,996 |
Short-term investments |  | 260 |  |  | 1,821 |  |  | 6,653 |
Other investments |  | 118,060 |  |  | 26,922 |  |  | 18,778 |
Investment expenses |  | (20,103) |  |  | (15,692) |  |  | (13,139) |
Net investment income earned |  | $ | 326,589 |  |  | 227,107 |  |  | 222,543 |
Schedule of realized and unrealized gains (losses) on securities |
($ in thousands) |  | 2021 |  | 2020 |  | 2019
Gross gains on sales |  | $ | 15,284 |  |  | 18,893 |  |  | 31,910 |
Gross losses on sales |  | (8,140) |  |  | (9,745) |  |  | (5,195) |
Net realized gains on disposals |  | 7,144 |  |  | 9,148 |  |  | 26,715 |
Net unrealized gains (losses) on equity securities |  | 17,881 |  |  | 7,939 |  |  | (8,649) |
Net credit loss (expense) on fixed maturities, AFS |  | (6,858) |  |  | (5,042) |  |  |
Net credit loss (expense) benefit on fixed maturities, HTM |  | (49) |  |  | 4 |  |  |
Losses on securities for which we have the intent to sell |  | (519) |  |  | (16,266) |  |  |
Net other-than-temporary-impairment ("OTTI") losses recognized in earnings |  |  |  |  |  | (3,644) |
Net realized and unrealized gains (losses) |  | $ | 17,599 |  |  | (4,217) |  |  | 14,422 |
Unrealized Gain (Loss) on Equity Securities |
($ in thousands) |  | 2021 |  | 2020 |  | 2019
Unrealized gains (losses) recognized in income on equity securities: |  |  |  |  |  |
On securities remaining in our portfolio at end of period |  | $ | 16,473 |  |  | 7,936 |  |  | 1,219 |
On securities sold in period |  | 1,408 |  |  | 3 |  |  | (9,868) |
Total unrealized gains (losses) recognized in income on equity securities |  | $ | 17,881 |  |  | 7,939 |  |  | (8,649) |

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