XML 84 R70.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Investments in Fixed Maturity Securities (Investments in Fixed Maturity Securities) (Details) - USD ($) $ in Thousands | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | --- | ---
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Amortized Cost | $ 44,437 | $ 53,415 |
Held-to-maturity, allowance for credit loss | (25) | (43) | $ (114)
Total held to maturity, Gross Unrealized Gains | 1,561 | 3,239 |
Total held to maturity, Gross Unrealized Losses | 0 | 0 |
Total held to maturity, Fair Value | 45,973 | 56,611 |
Carrying Value | 44,412 | 53,372 |
Fixed maturity securities available for sale at cost | 22,966,462 | 20,861,830 |
Cumulative effect adjustment resulting from changes in accounting principles | (646) | (36,708) | (37,352)
Total available for sale, Gross Unrealized Gains | 96,365 | 110,989 |
Total available for sale, Gross Unrealized Losses | (708,728) | (811,175) |
Total available for sale, Fair Value | 22,353,453 | 20,124,936 |
Total available for sale, Carrying Value | 22,353,453 | 20,124,936 |
Fixed maturity securities, amortized cost | 23,010,899 | 20,915,245 |
Total investments in fixed maturity securities, Gross Unrealized Gains | 97,926 | 114,228 |
Total investments in fixed maturity securities, Gross Unrealized Losses | (708,728) | (811,175) |
Total investments in fixed maturity securities, Fair Value | 22,399,426 | 20,181,547 |
Total investments in fixed maturity securities, carrying value | 22,397,865 | 20,178,308 |
Fixed maturity securities, allowance for credit loss | (671) | (36,751) |
State and municipal |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Amortized Cost | 42,145 | 50,547 |
Held-to-maturity, allowance for credit loss | (25) | (43) |
Total held to maturity, Gross Unrealized Gains | 1,492 | 3,132 |
Total held to maturity, Gross Unrealized Losses | 0 | 0 |
Total held to maturity, Fair Value | 43,612 | 53,636 |
Carrying Value | 42,120 | 50,504 |
Fixed maturity securities available for sale at cost | 2,376,541 | 2,742,922 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | (757) | 0
Total available for sale, Gross Unrealized Gains | 7,560 | 14,719 |
Total available for sale, Gross Unrealized Losses | (89,457) | (122,462) |
Total available for sale, Fair Value | 2,294,644 | 2,634,422 |
Total available for sale, Carrying Value | 2,294,644 | 2,634,422 |
Residential mortgage-backed |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Amortized Cost | 2,292 | 2,868 |
Held-to-maturity, allowance for credit loss | 0 | 0 |
Total held to maturity, Gross Unrealized Gains | 69 | 107 |
Total held to maturity, Gross Unrealized Losses | 0 | 0 |
Total held to maturity, Fair Value | 2,361 | 2,975 |
Carrying Value | 2,292 | 2,868 |
Fixed maturity securities available for sale at cost | 3,411,796 | 1,773,206 |
Cumulative effect adjustment resulting from changes in accounting principles | (5) | 0 |
Total available for sale, Gross Unrealized Gains | 11,047 | 12,780 |
Total available for sale, Gross Unrealized Losses | (189,630) | (163,844) |
Total available for sale, Fair Value | 3,233,208 | 1,622,142 |
Total available for sale, Carrying Value | 3,233,208 | 1,622,142 |
U.S. government and government agency |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 2,268,596 | 1,762,997 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | 0 |
Total available for sale, Gross Unrealized Gains | 9,608 | 11,403 |
Total available for sale, Gross Unrealized Losses | (42,863) | (57,669) |
Total available for sale, Fair Value | 2,235,341 | 1,716,731 |
Total available for sale, Carrying Value | 2,235,341 | 1,716,731 |
Special Revenue |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 1,581,778 | 1,682,550 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | 0 |
Total available for sale, Gross Unrealized Gains | 3,521 | 5,651 |
Total available for sale, Gross Unrealized Losses | (67,591) | (82,006) |
Total available for sale, Fair Value | 1,517,708 | 1,606,195 |
Total available for sale, Carrying Value | 1,517,708 | 1,606,195 |
Debt, State Government |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 272,936 | 394,429 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | 0 |
Total available for sale, Gross Unrealized Gains | 1,439 | 3,550 |
Total available for sale, Gross Unrealized Losses | (8,981) | (16,405) |
Total available for sale, Fair Value | 265,394 | 381,574 |
Total available for sale, Carrying Value | 265,394 | 381,574 |
Revenue Subject to Refund |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 85,340 | 103,029 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | 0 |
Total available for sale, Gross Unrealized Gains | 599 | 1,634 |
Total available for sale, Gross Unrealized Losses | (347) | (185) |
Total available for sale, Fair Value | 85,592 | 104,478 |
Total available for sale, Carrying Value | 85,592 | 104,478 |
Corporation |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 158,322 | 166,873 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | (757) |
Total available for sale, Gross Unrealized Gains | 1,079 | 696 |
Total available for sale, Gross Unrealized Losses | (5,827) | (11,973) |
Total available for sale, Fair Value | 153,574 | 154,839 |
Total available for sale, Carrying Value | 153,574 | 154,839 |
Debt, Local Government |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 278,165 | 396,041 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | 0 |
Total available for sale, Gross Unrealized Gains | 922 | 3,188 |
Total available for sale, Gross Unrealized Losses | (6,711) | (11,893) |
Total available for sale, Fair Value | 272,376 | 387,336 |
Total available for sale, Carrying Value | 272,376 | 387,336 |
Commercial Mortgage Backed Securities |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 534,936 | 657,157 |
Cumulative effect adjustment resulting from changes in accounting principles | (425) | (158) |
Total available for sale, Gross Unrealized Gains | 1,201 | 626 |
Total available for sale, Gross Unrealized Losses | (3,430) | (13,312) |
Total available for sale, Fair Value | 532,282 | 644,313 |
Total available for sale, Carrying Value | 532,282 | 644,313 |
Mortgage- Backed |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 3,946,732 | 2,430,363 |
Cumulative effect adjustment resulting from changes in accounting principles | (430) | (158) | (18)
Total available for sale, Gross Unrealized Gains | 12,248 | 13,406 |
Total available for sale, Gross Unrealized Losses | (193,060) | (177,156) |
Total available for sale, Fair Value | 3,765,490 | 2,266,455 |
Total available for sale, Carrying Value | 3,765,490 | 2,266,455 |
Asset-backed Securities |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 3,910,363 | 4,252,883 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | (1,164) | 0
Total available for sale, Gross Unrealized Gains | 16,161 | 8,527 |
Total available for sale, Gross Unrealized Losses | (41,512) | (73,206) |
Total available for sale, Fair Value | 3,885,012 | 4,187,040 |
Total available for sale, Carrying Value | 3,885,012 | 4,187,040 |
Industrial Property |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 3,746,501 | 3,679,219 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | (40) |
Total available for sale, Gross Unrealized Gains | 14,518 | 24,312 |
Total available for sale, Gross Unrealized Losses | (93,820) | (143,936) |
Total available for sale, Fair Value | 3,667,199 | 3,559,555 |
Total available for sale, Carrying Value | 3,667,199 | 3,559,555 |
Debt Security, Corporate, US |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 3,339,718 | 2,838,220 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | (4,986) |
Total available for sale, Gross Unrealized Gains | 18,871 | 14,681 |
Total available for sale, Gross Unrealized Losses | (38,076) | (68,681) |
Total available for sale, Fair Value | 3,320,513 | 2,779,234 |
Total available for sale, Carrying Value | 3,320,513 | 2,779,234 |
Public Utility, Bonds |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 795,839 | 701,865 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | 0 |
Total available for sale, Gross Unrealized Gains | 2,970 | 6,471 |
Total available for sale, Gross Unrealized Losses | (20,115) | (23,412) |
Total available for sale, Fair Value | 778,694 | 684,924 |
Total available for sale, Carrying Value | 778,694 | 684,924 |
Other Security Investments |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 653,194 | 635,975 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | 0 |
Total available for sale, Gross Unrealized Gains | 2,493 | 1,605 |
Total available for sale, Gross Unrealized Losses | (4,452) | (7,234) |
Total available for sale, Fair Value | 651,235 | 630,346 |
Total available for sale, Carrying Value | 651,235 | 630,346 |
Corporate |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 8,535,252 | 7,855,279 |
Cumulative effect adjustment resulting from changes in accounting principles | 0 | (5,026) | (4,701)
Total available for sale, Gross Unrealized Gains | 38,852 | 47,069 |
Total available for sale, Gross Unrealized Losses | (156,463) | (243,263) |
Total available for sale, Fair Value | 8,417,641 | 7,654,059 |
Total available for sale, Carrying Value | 8,417,641 | 7,654,059 |
Foreign government |  |  |
Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Line Items] |  |  |
Fixed maturity securities available for sale at cost | 1,928,978 | 1,817,386 |
Cumulative effect adjustment resulting from changes in accounting principles | (216) | (29,603) | $ (32,633)
Total available for sale, Gross Unrealized Gains | 11,936 | 15,865 |
Total available for sale, Gross Unrealized Losses | (185,373) | (137,419) |
Total available for sale, Fair Value | 1,755,325 | 1,666,229 |
Total available for sale, Carrying Value | $ 1,755,325 | $ 1,666,229 |

X
- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479130/326-30-45-1 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 103 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-103 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 100 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-100 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (bbb)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-2 Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481830/320-10-45-1 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479130/326-30-45-1 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aaa) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479130/326-30-45-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-9 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-9 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleAllowanceForCreditLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity) and investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481830/320-10-45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of investment in debt security measured at amortized cost (held-to-maturity) and investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5A Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-2 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSaleAndHeldToMaturityFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of allowance for credit loss for debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (aaa) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479344/326-20-45-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-13 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-13 + Details
Name: | us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481830/320-10-45-1 + Details
Name: | us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostAfterAllowanceForCreditLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount, before allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7A -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-7A Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479344/326-20-45-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 14 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-14 + Details
Name: | us-gaap_HeldToMaturitySecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5A -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5A + Details
Name: | us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5A -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5A + Details
Name: | us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2E -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E Reference 3: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (aa) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 5A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-5A Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 + Details
Name: | us-gaap_HeldToMaturitySecuritiesFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Available For Sale Securities Debt Securities Fair Value + References No definition available. + Details
Name: | wrb_AvailableForSaleSecuritiesDebtSecuritiesFairValue
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Available For Sale Securities Debt Securities Gross Unrealized Gain + References No definition available. + Details
Name: | wrb_AvailableForSaleSecuritiesDebtSecuritiesGrossUnrealizedGain
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Available For Sale Securities Debt Securities Gross Unrealized Losses + References No definition available. + Details
Name: | wrb_AvailableForSaleSecuritiesDebtSecuritiesGrossUnrealizedLosses
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Securities, Allowance for Credit Loss + References No definition available. + Details
Name: | wrb_DebtSecuritiesAllowanceforCreditLoss
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Debt Securities, Available-for-sale and Held-to-maturity, Amortized Cost + References No definition available. + Details
Name: | wrb_DebtSecuritiesAvailableforsaleandHeldtomaturityAmortizedCost
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Debt Securities, Available-for-sale and Held-to-maturity, Gross Unrealized Gains + References No definition available. + Details
Name: | wrb_DebtSecuritiesAvailableforsaleandHeldtomaturityGrossUnrealizedGains
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Debt Securities, Available-for-sale and Held-to-maturity, Gross Unrealized Losses + References No definition available. + Details
Name: | wrb_DebtSecuritiesAvailableforsaleandHeldtomaturityGrossUnrealizedLosses
Namespace Prefix: | wrb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition [Line Items] for Schedule of Available-for-sale and Held-to-maturity Securities [Table] [Table] + References No definition available. + Details
Name: | wrb_ScheduleofAvailableforsaleandHeldtomaturitySecuritiesTableLineItems
Namespace Prefix: | wrb_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=wrb_SpecialRevenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_SovereignDebtStateGovernmentUnspecifiedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_RevenueSubjectToRefundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CorporationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_SovereignDebtLocalGovernmentUnspecifiedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=srt_IndustrialPropertyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_DomesticCorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_PublicUtilityBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_OtherAggregatedInvestmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |