XML 83 R72.htm IDEA: XBRL DOCUMENT
v3.20.2

Segment Information (Operations By Segment) (Detail) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | $ 9,078 | $ 8,622 | $ 25,410 | $ 24,278
Net premiums earned | 8,765 | 8,327 | 24,687 | 23,355
Losses and loss expenses | 5,835 | 5,052 | 16,897 | 13,865
Policy benefits | 198 | 158 | 550 | 515
Policy acquisition costs | 1,645 | 1,603 | 4,853 | 4,611
Administrative expenses | 733 | 752 | 2,201 | 2,220
Underwriting income (loss) | 354 | 762 | 186 | 2,144
Net investment income (loss) | 840 | 873 | 2,528 | 2,568
Other (income) expense | (485) | (57) | (372) | (326)
Amortization of purchased intangibles | 72 | 76 | 217 | 229
Segment Income (loss) | 1,607 | 1,616 | 2,869 | 4,809
Net gains (losses) recognized during the period | (141) | (155) | (1,069) | (475)
Interest expense | 130 | 138 | 390 | 418
Chubb integration expenses | 0 | 2 | 0 | 9
Income tax expense | 142 | 230 | 295 | 626
Net income | 1,194 | 1,091 | 1,115 | 3,281
Segment Reconciling Items |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 0 | 0 | 0 | 0
Net premiums earned | 0 | 0 | 0 | 0
Losses and loss expenses | 1 | (14) | (2) | (8)
Policy benefits | 24 | (7) | 8 | 20
Policy acquisition costs | 0 | 0 | 0 | 0
Administrative expenses | 0 | 0 | 0 | 0
Underwriting income (loss) | (25) | 21 | (6) | (12)
Net investment income (loss) | (32) | (21) | (64) | (62)
Other (income) expense | (56) | (14) | (72) | (82)
Amortization of purchased intangibles | 0 | 0 | 0 | 0
Segment Income (loss) | (1) | 14 | 2 | 8
Net gains (losses) recognized during the period | 1 | (14) | (2) | (8)
Interest expense | 0 | 0 | 0 | 0
Chubb integration expenses |  | 0 |  | 0
Income tax expense | 0 | 0 | 0 | 0
Net income | 0 | 0 | 0 | 0
North America Commercial P&C Insurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 3,778 | 3,452 | 10,750 | 9,937
Net premiums earned | 3,456 | 3,185 | 10,427 | 9,660
Losses and loss expenses | 2,444 | 2,051 | 8,123 | 6,238
Policy benefits | 0 | 0 |  | 0
Policy acquisition costs | 489 | 459 | 1,452 | 1,377
Administrative expenses | 243 | 256 | 751 | 755
Underwriting income (loss) | 280 | 419 | 101 | 1,290
Net investment income (loss) | 510 | 538 | 1,544 | 1,584
Other (income) expense | 7 | 5 | 19 | 17
Amortization of purchased intangibles | 0 | 0 | 0 | 0
Segment Income (loss) | 783 | 952 | 1,626 | 2,857
North America Personal P&C Insurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 1,285 | 1,251 | 3,719 | 3,616
Net premiums earned | 1,231 | 1,187 | 3,623 | 3,509
Losses and loss expenses | 961 | 674 | 2,406 | 2,178
Policy benefits | 0 | 0 | 0 | 0
Policy acquisition costs | 248 | 240 | 724 | 708
Administrative expenses | 65 | 72 | 199 | 211
Underwriting income (loss) | (43) | 201 | 294 | 412
Net investment income (loss) | 64 | 66 | 195 | 194
Other (income) expense | 1 | 1 | 4 | 2
Amortization of purchased intangibles | 2 | 3 | 8 | 9
Segment Income (loss) | 18 | 263 | 477 | 595
North America Agricultural Insurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 986 | 938 | 1,604 | 1,534
Net premiums earned | 971 | 941 | 1,441 | 1,374
Losses and loss expenses | 845 | 880 | 1,223 | 1,163
Policy benefits | 0 | 0 | 0 | 0
Policy acquisition costs | 56 | 56 | 96 | 90
Administrative expenses | 5 | 4 | 12 | 9
Underwriting income (loss) | 65 | 1 | 110 | 112
Net investment income (loss) | 7 | 8 | 23 | 22
Other (income) expense | 0 | 0 | 1 | 1
Amortization of purchased intangibles | 7 | 7 | 20 | 21
Segment Income (loss) | 65 | 2 | 112 | 112
Overseas General Insurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 2,238 | 2,228 | 6,857 | 6,881
Net premiums earned | 2,337 | 2,256 | 6,838 | 6,595
Losses and loss expenses | 1,192 | 1,154 | 3,935 | 3,385
Policy benefits | 0 | 0 | 0 | 0
Policy acquisition costs | 637 | 630 | 1,903 | 1,855
Administrative expenses | 260 | 257 | 759 | 771
Underwriting income (loss) | 248 | 215 | 241 | 584
Net investment income (loss) | 130 | 147 | 396 | 444
Other (income) expense | 1 | 2 | 10 | 11
Amortization of purchased intangibles | 10 | 11 | 33 | 34
Segment Income (loss) | 367 | 349 | 594 | 983
Global Reinsurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 181 | 141 | 606 | 540
Net premiums earned | 171 | 160 | 520 | 487
Losses and loss expenses | 154 | 79 | 314 | 245
Policy benefits | 0 | 0 | 0 | 0
Policy acquisition costs | 40 | 42 | 127 | 127
Administrative expenses | 9 | 9 | 28 | 26
Underwriting income (loss) | (32) | 30 | 51 | 89
Net investment income (loss) | 85 | 71 | 214 | 206
Other (income) expense | 0 | 0 | 1 | 0
Amortization of purchased intangibles | 0 | 0 | 0 | 0
Segment Income (loss) | 53 | 101 | 264 | 295
Life Insurance [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 610 | 612 | 1,874 | 1,770
Net premiums earned | 599 | 598 | 1,838 | 1,730
Losses and loss expenses | 183 | 190 | 556 | 581
Policy benefits | 174 | 165 | 542 | 495
Policy acquisition costs | 175 | 176 | 551 | 454
Administrative expenses | 80 | 80 | 238 | 237
Underwriting income (loss) | (13) | (13) | (49) | (37)
Net investment income (loss) | 95 | 92 | 285 | 278
Other (income) expense | (23) | (17) | (52) | (37)
Amortization of purchased intangibles | 1 | 1 | 3 | 2
Segment Income (loss) | 104 | 95 | 285 | 276
Corporate Segment [Member] |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net premiums written | 0 | 0 | 0 | 0
Net premiums earned | 0 | 0 | 0 | 0
Losses and loss expenses | 55 | 38 | 342 | 83
Policy benefits | 0 | 0 | 0 | 0
Policy acquisition costs | 0 | 0 | 0 | 0
Administrative expenses | 71 | 74 | 214 | 211
Underwriting income (loss) | (126) | (112) | (556) | (294)
Net investment income (loss) | (19) | (28) | (65) | (98)
Other (income) expense | (415) | (34) | (283) | (238)
Amortization of purchased intangibles | 52 | 54 | 153 | 163
Segment Income (loss) | 218 | (160) | (491) | (317)
Net gains (losses) recognized during the period | (142) | (141) | (1,067) | (467)
Interest expense | 130 | 138 | 390 | 418
Chubb integration expenses |  | 2 |  | 9
Income tax expense | 142 | 230 | 295 | 626
Net income | $ (196) | $ (671) | $ (2,243) | $ (1,837)

X
- Definition Segment Underwriting Income Loss, Net Investment Income Loss, and Other Income expense allocated to the segment + References No definition available. + Details
Name: | cb_SegmentUnderwritingIncomeLossandNetInvestmentIncomeLoss
Namespace Prefix: | cb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274 + Details
Name: | us-gaap_AmortizationOfIntangibleAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs. + References No definition available. + Details
Name: | us-gaap_BusinessCombinationIntegrationRelatedCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of amortization expense (reversal of expense) for deferred policy acquisition costs. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 30 -Section 55 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121638166&loc=d3e11522-158419 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 45 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6480726&loc=d3e6691-158385 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 65 -Paragraph 2 -Subparagraph (g)(1) -URI http://asc.fasb.org/extlink&oid=121370832&loc=SL117420844-207641 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(7)(a)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 30 -Section 50 -Paragraph 2B -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121638524&loc=SL117422543-158416 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=35755530&loc=d3e11264-158415 + Details
Name: | us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The aggregate total of expenses of managing and administering the affairs of an entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.4) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 + Details
Name: | us-gaap_GeneralAndAdministrativeExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 6.I.7) -URI http://asc.fasb.org/extlink&oid=116825942&loc=d3e330036-122817 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32672-109319 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(h)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 20 -Section 45 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=120385591&loc=d3e38679-109324 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(9)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794 + Details
Name: | us-gaap_IncomeTaxExpenseBenefit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The net amount of operating interest income (expense). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.10) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 + Details
Name: | us-gaap_InterestIncomeExpenseNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of expense (income) recognized due to changes in the accrued obligation to policyholders that relates to insured events. + References No definition available. + Details
Name: | us-gaap_LiabilityForFuturePolicyBenefitsPeriodExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669619-108580 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 31 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 11 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(22)) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 11 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 32 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22595-107794 Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1B -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669625-108580 Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599 Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(18)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(20)) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 Reference 13: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 Reference 14: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b)(2) -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794 Reference 15: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22663-107794 Reference 16: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 28 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612 Reference 17: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 30 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599 Reference 18: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794 Reference 19: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(g)(1)(ii)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 20: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 60B -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121326447&loc=SL5780133-109256 Reference 21: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 Reference 22: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 32 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599 Reference 23: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22658-107794 + Details
Name: | us-gaap_NetIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(2)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 + Details
Name: | us-gaap_NetInvestmentIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The net amount of other operating income and expenses, the components of which are not separately disclosed on the income statement, from items that are associated with the entity's normal revenue producing operations. + References No definition available. + Details
Name: | us-gaap_OtherOperatingIncomeExpenseNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.5) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=99397103&loc=d3e6811-158387 + Details
Name: | us-gaap_PolicyholderBenefitsAndClaimsIncurredNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums earned. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(1)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 235 -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17(Column E)) -URI http://asc.fasb.org/extlink&oid=120401096&loc=d3e574992-122915 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)(c)) -URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 + Details
Name: | us-gaap_PremiumsEarnedNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums written. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 + Details
Name: | us-gaap_PremiumsWrittenNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of realized gain (loss) on investment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.3(a)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 + Details
Name: | us-gaap_RealizedInvestmentGainsLosses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The difference between the price paid by the public and the contract price less the related expenses. A broker-dealer may underwrite a security offering by contracting to buy the issue either at a fixed price or a price based on selling the offering on a best-effort basis. + References No definition available. + Details
Name: | us-gaap_UnderwritingIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | srt_ConsolidationItemsAxis=us-gaap_MaterialReconcilingItemsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_SegmentInsuranceNorthAmericanCommercialPCMemberMemberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_SegmentInsuranceNorthAmericanPersonalPCMemberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_SegmentInsuranceNorthAmericanAgricultureMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_SegmentInsuranceOverseasGeneralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_SegmentGlobalReinsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_SegmentLifeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=us-gaap_CorporateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |