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Information provided in connection with outstanding debt of subsidiaries (Condensed Consolidating Balance Sheet) (Detail) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016 | Jan. 14, 2016 | Dec. 31, 2015 | Dec. 31, 2014
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Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items] |  |  |  |  |  |  |  |  |  |
Investments |  | $ 102,444 |  | $ 99,094 |  |  |  |  |  |
Cash |  | 728 | [1],[2] | 985 | [1],[3],[4] |  | $ 1,775 | [1],[5] | $ 655 | [5]
Insurance and reinsurance balances receivable |  | 9,334 |  | 8,970 |  |  |  |  |  |
Reinsurance recoverable on losses and loss expenses |  | 15,034 |  | 13,577 |  |  |  |  |  |
Reinsurance Recoverable Future Policy Benefits | [6] | 184 |  | 182 |  |  |  |  |  |
Value of business acquired |  | 326 |  | 355 |  |  | 395 |  | 466 |
Goodwill |  | 22,054 |  | 22,095 |  |  |  |  |  |
Other assets |  | 16,918 |  | 14,528 |  |  |  |  |  |
Total assets |  | 167,022 |  | 159,786 |  |  |  |  |  |
Unpaid losses and loss expenses |  | 63,179 |  | 60,540 |  |  | 37,303 |  | 38,315 |
Unearned premiums |  | 15,216 |  | 14,779 |  |  |  |  |  |
Future policy benefits |  | 5,321 |  | 5,036 |  |  |  |  |  |
Affiliated notional cash pooling program |  | 300 |  | 0 | [4] |  |  |  |  |
Repurchase agreements |  | 1,408 |  | 1,403 |  |  |  |  |  |
Short-term debt |  | 1,013 |  | 500 |  |  |  |  |  |
Long-term debt |  | 11,556 |  | 12,610 |  |  |  |  |  |
Trust preferred securities |  | 308 |  | 308 |  |  |  |  |  |
Other liabilities |  | 17,849 |  | 16,335 |  |  |  |  |  |
Total liabilities |  | 115,850 |  | 111,511 |  |  |  |  |  |
Total shareholders' equity |  | 51,172 |  | 48,275 |  |  |  |  |  |
Total liabilities and shareholders’ equity |  | 167,022 |  | 159,786 |  |  |  |  |  |
Consolidating Adjustments |  |  |  |  |  |  |  |  |  |
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items] |  |  |  |  |  |  |  |  |  |
Cash |  | (115) | [1],[2] | (982) | [1],[3],[4] |  | (971) | [1],[5] | (555) | [5]
Insurance and reinsurance balances receivable |  | (1,486) |  | (1,528) |  |  |  |  |  |
Reinsurance recoverable on losses and loss expenses |  | (12,480) |  | (10,919) |  |  |  |  |  |
Reinsurance Recoverable Future Policy Benefits |  | (1,010) |  | (971) |  |  |  |  |  |
Investments in subsidiaries |  | (93,074) |  | (87,917) |  |  |  |  |  |
Due from subsidiaries and affiliates, net |  | (9,639) |  | (10,482) |  |  |  |  |  |
Other assets |  | (4,073) |  | (4,353) |  |  |  |  |  |
Total assets |  | (121,877) |  | (117,152) |  |  |  |  |  |
Unpaid losses and loss expenses |  | (11,588) |  | (10,143) |  |  |  |  |  |
Unearned premiums |  | (3,659) |  | (3,759) |  |  |  |  |  |
Future policy benefits |  | (1,010) |  | (971) |  |  |  |  |  |
Due to subsidiaries and affiliates, net |  | (9,639) |  | (10,482) |  |  |  |  |  |
Affiliated notional cash pooling program |  | (115) | [2] | (982) | [4] |  |  |  |  |
Repurchase agreements |  | 0 |  | 0 |  |  |  |  |  |
Other liabilities |  | (2,792) |  | (2,898) |  |  |  |  |  |
Total liabilities |  | (28,803) |  | (29,235) |  |  |  |  |  |
Total shareholders' equity |  | (93,074) |  | (87,917) |  |  |  |  |  |
Total liabilities and shareholders’ equity |  | (121,877) |  | (117,152) |  |  |  |  |  |
Chubb limited (Parent Guarantor) |  |  |  |  |  |  |  |  |  |
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items] |  |  |  |  |  |  |  |  |  |
Investments |  |  |  | 27 |  |  |  |  |  |
Cash |  | 3 | [1],[2] | 1 | [1],[3],[4] |  | 1 | [1],[5] | 0 | [5]
Investments in subsidiaries |  | 41,909 |  | 38,408 |  |  |  |  |  |
Due from subsidiaries and affiliates, net |  | 9,639 |  | 10,482 |  |  |  |  |  |
Other assets |  | 3 |  | 3 |  |  |  |  |  |
Total assets |  | 51,554 |  | 48,921 |  |  |  |  |  |
Affiliated notional cash pooling program |  | 0 |  | 363 | [4] |  |  |  |  |
Repurchase agreements |  | 0 |  | 0 |  |  |  |  |  |
Other liabilities |  | 382 |  | 283 |  |  |  |  |  |
Total liabilities |  | 382 |  | 646 |  |  |  |  |  |
Total shareholders' equity |  | 51,172 |  | 48,275 |  |  |  |  |  |
Total liabilities and shareholders’ equity |  | 51,554 |  | 48,921 |  |  |  |  |  |
Chubb INA Holdings Inc. (Subsidiary Issuer) |  |  |  |  |  |  |  |  |  |
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items] |  |  |  |  |  |  |  |  |  |
Investments |  | 168 |  | 485 |  |  |  |  |  |
Cash |  | 1 | [1],[2] | 1 | [1],[3],[4] |  | 2 | [1],[5] | 1 | [5]
Investments in subsidiaries |  | 51,165 |  | 49,509 |  |  |  |  |  |
Other assets |  | 287 |  | 436 |  |  |  |  |  |
Total assets |  | 51,621 |  | 50,431 |  |  |  |  |  |
Due to subsidiaries and affiliates, net |  | 9,432 |  | 10,209 |  |  |  |  |  |
Affiliated notional cash pooling program |  | 115 | [2] | 619 | [4] |  |  |  |  |
Repurchase agreements |  | 0 |  | 0 |  |  |  |  |  |
Short-term debt |  | 1,013 |  | 500 |  |  |  |  |  |
Long-term debt |  | 11,546 |  | 12,599 |  |  |  |  |  |
Trust preferred securities |  | 308 |  | 308 |  |  |  |  |  |
Other liabilities |  | 1,411 |  | 1,582 |  |  |  |  |  |
Total liabilities |  | 23,825 |  | 25,817 |  |  |  |  |  |
Total shareholders' equity |  | 27,796 |  | 24,614 |  |  |  |  |  |
Total liabilities and shareholders’ equity |  | 51,621 |  | 50,431 |  |  |  |  |  |
Other Chubb Limited Subsidiaries and Eliminations |  |  |  |  |  |  |  |  |  |
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items] |  |  |  |  |  |  |  |  |  |
Investments |  | 102,276 |  | 98,582 |  |  |  |  |  |
Cash |  | 839 | [1],[2] | 1,965 | [1],[3],[4] |  | $ 2,743 | [5] | $ 1,209 | [5]
Insurance and reinsurance balances receivable |  | 10,820 |  | 10,498 |  |  |  |  |  |
Reinsurance recoverable on losses and loss expenses |  | 27,514 |  | 24,496 |  |  |  |  |  |
Reinsurance Recoverable Future Policy Benefits |  | 1,194 |  | 1,153 |  |  |  |  |  |
Value of business acquired |  | 326 |  | 355 |  |  |  |  |  |
Goodwill |  | 22,054 |  | 22,095 |  |  |  |  |  |
Other assets |  | 20,701 |  | 18,442 |  |  |  |  |  |
Total assets |  | 185,724 |  | 177,586 |  |  |  |  |  |
Unpaid losses and loss expenses |  | 74,767 |  | 70,683 |  |  |  |  |  |
Unearned premiums |  | 18,875 |  | 18,538 |  |  |  |  |  |
Future policy benefits |  | 6,331 |  | 6,007 |  |  |  |  |  |
Due to subsidiaries and affiliates, net |  | 207 |  | 273 |  |  |  |  |  |
Repurchase agreements |  | 1,408 |  | 1,403 |  |  |  |  |  |
Long-term debt |  | 10 |  | 11 |  |  |  |  |  |
Other liabilities |  | 18,848 |  | 17,368 |  |  |  |  |  |
Total liabilities |  | 120,446 |  | 114,283 |  |  |  |  |  |
Total shareholders' equity |  | 65,278 |  | 63,303 |  |  |  |  |  |
Total liabilities and shareholders’ equity |  | $ 185,724 |  | $ 177,586 |  |  |  |  |  |
The Chubb Corporation [Member] |  |  |  |  |  |  |  |  |  |
Information Provided In Connection With Outstanding Debt Of Subsidiaries [Line Items] |  |  |  |  |  |  |  |  |  |
Investments |  |  |  |  |  | $ 42,967 |  |  |  |
Cash |  |  |  |  |  | 71 |  |  |  |
Insurance and reinsurance balances receivable |  |  |  |  |  | 3,095 |  |  |  |
Unpaid losses and loss expenses |  |  |  |  |  | 22,923 |  |  |  |
Unearned premiums |  |  |  |  |  | 7,011 |  |  |  |
Long-term debt |  |  |  |  |  | $ 3,765 |  |  |  |
[1] | Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017 and 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[2] | Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2017, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[3] | Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016 and 2015, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[4] | Chubb maintains two notional multicurrency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2016, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[5] | Chubb maintains two notional multi-currency cash pools (Pools) with a third-party bank. Refer to Note 1 f) for additional information. At December 31, 2015 and 2014, the cash balance of one or more entities was negative; however, the overall Pool balances were positive.
[6] | (1) Net of a provision for uncollectible reinsurance.

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- Definition The amount needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=65670824&loc=d3e14764-158437 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (cc) -URI http://asc.fasb.org/extlink&oid=65670824&loc=d3e14764-158437 + Details
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- Definition Amount of accrued obligation to policyholders that relates to insured events for long-duration contracts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 25 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=28366191&loc=d3e13145-158430 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (cc) -URI http://asc.fasb.org/extlink&oid=65670824&loc=d3e14764-158437 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.13(a)(1)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=65670824&loc=d3e14764-158437 + Details
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- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Amount of liabilities classified as other. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.15) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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- Definition The carrying amount as of the balance sheet date due the entity from (a) agents and insureds, (b) uncollected premiums and (c) others, net of the allowance for doubtful accounts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.(a),5) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
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- Definition Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(m)(1)(a)(i)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.13(1)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226008-175313 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=49176635&loc=d3e9760-107771 + Details
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- Definition Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 55 -Paragraph 4I -URI http://asc.fasb.org/extlink&oid=84234705&loc=SL4590271-111686 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 16 -URI http://asc.fasb.org/extlink&oid=96868048&loc=SL4568740-111683 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=96868048&loc=SL4568447-111683 + Details
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- Definition Carrying amount of premiums written on insurance contracts that have not been earned as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(13)(a)(2)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 235 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-16(Column D)) -URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574960-122915 + Details
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