XML 146 R129.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Business Segments (Income Statement Information) (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Segment Reporting Information [Line Items] |  |  |  |
Net written premiums |  | $ 7,069 | $ 6,988 | $ 6,962
Operating revenues |  |  |  |
Net earned premiums |  | 6,988 | 6,924 | 6,921
Net investment income |  | 2,034 | 1,988 | 1,840
Other revenues |  | 427 | 404 | 407
Total operating revenues |  | 9,449 | 9,316 | 9,168
Claims, Benefits and Expenses |  |  |  |
Net incurred claims and benefits |  | 5,288 | 5,270 | 5,372
Policyholders’ dividends |  | 22 | 13 | 12
Amortization of deferred acquisition costs |  | 1,233 | 1,235 | 1,540
Other insurance related expenses |  | 1,098 | 1,122 | 1,093
Other expenses |  | 591 | 589 | 535
Total claims, benefits and expenses |  | 8,232 | 8,229 | 8,552
Core income (loss) before income tax |  | 1,217 | 1,087 | 616
Income tax (expense) benefit on core income (loss) |  | (298) | (263) | (101)
Core income (loss) |  | 919 | 824 | 515
Net realized investment gains (losses) |  | 93 | 50 | (67)
Income tax (expense) benefit on net realized investment gains (losses) |  | (30) | (15) | 31
Net realized investment gains (losses), after tax |  | 63 | 35 | (36)
Net deferred tax asset remeasurement | $ (83) | (83) | 0 | 0
Net income |  | 899 | 859 | 479
Operating Segments | Specialty |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net written premiums |  | 2,771 | 2,780 | 2,781
Operating revenues |  |  |  |
Net earned premiums |  | 2,753 | 2,779 | 2,782
Net investment income |  | 538 | 516 | 474
Other revenues |  | 392 | 362 | 356
Total operating revenues |  | 3,683 | 3,657 | 3,612
Claims, Benefits and Expenses |  |  |  |
Net incurred claims and benefits |  | 1,535 | 1,467 | 1,597
Policyholders’ dividends |  | 4 | 4 | 4
Amortization of deferred acquisition costs |  | 596 | 591 | 589
Other insurance related expenses |  | 286 | 301 | 278
Other expenses |  | 342 | 312 | 301
Total claims, benefits and expenses |  | 2,763 | 2,675 | 2,769
Core income (loss) before income tax |  | 920 | 982 | 843
Income tax (expense) benefit on core income (loss) |  | (310) | (332) | (283)
Core income (loss) |  | 610 | 650 | 560
Operating Segments | Commercial |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net written premiums |  | 2,882 | 2,841 | 2,818
Operating revenues |  |  |  |
Net earned premiums |  | 2,840 | 2,804 | 2,788
Net investment income |  | 642 | 638 | 593
Other revenues |  | 31 | 32 | 37
Total operating revenues |  | 3,513 | 3,474 | 3,418
Claims, Benefits and Expenses |  |  |  |
Net incurred claims and benefits |  | 1,928 | 1,927 | 1,814
Policyholders’ dividends |  | 18 | 9 | 8
Amortization of deferred acquisition costs |  | 475 | 470 | 469
Other insurance related expenses |  | 523 | 560 | 538
Other expenses |  | 57 | 36 | 28
Total claims, benefits and expenses |  | 3,001 | 3,002 | 2,857
Core income (loss) before income tax |  | 512 | 472 | 561
Income tax (expense) benefit on core income (loss) |  | (171) | (161) | (192)
Core income (loss) |  | 341 | 311 | 369
Operating Segments | International |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net written premiums |  | 881 | 821 | 822
Operating revenues |  |  |  |
Net earned premiums |  | 857 | 806 | 804
Net investment income |  | 52 | 51 | 52
Other revenues |  | 0 | 0 | (1)
Total operating revenues |  | 909 | 857 | 855
Claims, Benefits and Expenses |  |  |  |
Net incurred claims and benefits |  | 575 | 492 | 479
Policyholders’ dividends |  | 0 | 0 | 0
Amortization of deferred acquisition costs |  | 162 | 174 | 168
Other insurance related expenses |  | 162 | 133 | 138
Other expenses |  | (7) | 24 | 12
Total claims, benefits and expenses |  | 892 | 823 | 797
Core income (loss) before income tax |  | 17 | 34 | 58
Income tax (expense) benefit on core income (loss) |  | (9) | (13) | (21)
Core income (loss) |  | 8 | 21 | 37
Operating Segments | Life & Group |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net written premiums |  | 536 | 547 | 542
Operating revenues |  |  |  |
Net earned premiums |  | 539 | 536 | 548
Net investment income |  | 782 | 767 | 704
Other revenues |  | 2 | (2) | 7
Total operating revenues |  | 1,323 | 1,301 | 1,259
Claims, Benefits and Expenses |  |  |  |
Net incurred claims and benefits |  | 1,269 | 1,286 | 1,421
Policyholders’ dividends |  | 0 | 0 | 0
Amortization of deferred acquisition costs |  | 0 | 0 | 314
Other insurance related expenses |  | 129 | 132 | 142
Other expenses |  | 7 | 8 | 11
Total claims, benefits and expenses |  | 1,405 | 1,426 | 1,888
Core income (loss) before income tax |  | (82) | (125) | (629)
Income tax (expense) benefit on core income (loss) |  | 132 | 145 | 315
Core income (loss) |  | 50 | 20 | (314)
Operating Segments | Corporate & Other |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net written premiums |  | 0 | 0 | 1
Operating revenues |  |  |  |
Net earned premiums |  | 0 | 0 | 1
Net investment income |  | 20 | 16 | 17
Other revenues |  | 2 | 12 | 11
Total operating revenues |  | 22 | 28 | 29
Claims, Benefits and Expenses |  |  |  |
Net incurred claims and benefits |  | (19) | 98 | 61
Policyholders’ dividends |  | 0 | 0 | 0
Amortization of deferred acquisition costs |  | 0 | 0 | 0
Other insurance related expenses |  | (1) | (3) | (1)
Other expenses |  | 192 | 209 | 186
Total claims, benefits and expenses |  | 172 | 304 | 246
Core income (loss) before income tax |  | (150) | (276) | (217)
Income tax (expense) benefit on core income (loss) |  | 60 | 98 | 80
Core income (loss) |  | (90) | (178) | (137)
Eliminations |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Net written premiums |  | (1) | (1) | (2)
Operating revenues |  |  |  |
Net earned premiums |  | (1) | (1) | (2)
Net investment income |  | 0 | 0 | 0
Other revenues |  | 0 | 0 | (3)
Total operating revenues |  | (1) | (1) | (5)
Claims, Benefits and Expenses |  |  |  |
Net incurred claims and benefits |  | 0 | 0 | 0
Policyholders’ dividends |  | 0 | 0 | 0
Amortization of deferred acquisition costs |  | 0 | 0 | 0
Other insurance related expenses |  | (1) | (1) | (2)
Other expenses |  | 0 | 0 | (3)
Total claims, benefits and expenses |  | (1) | (1) | (5)
Core income (loss) before income tax |  | 0 | 0 | 0
Income tax (expense) benefit on core income (loss) |  | 0 | 0 | 0
Core income (loss) |  | $ 0 | $ 0 | $ 0

X
- Definition Effective Income Tax Rate Reconciliation, Effect of Tax Cuts and Jobs Act of 2017, Amount + References No definition available. + Details
Name: | cna_EffectiveIncomeTaxRateReconciliationEffectofTaxCutsandJobsActof2017Amount
Namespace Prefix: | cna_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Income Tax Expense (Benefit) on Net Realized Investment Gains Losses + References No definition available. + Details
Name: | cna_IncomeTaxExpenseBenefitOnNetRealizedInvestmentGainsLosses
Namespace Prefix: | cna_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Income Tax Expense (Benefit) on Operating Income (Loss) + References No definition available. + Details
Name: | cna_IncomeTaxExpenseBenefitOnOperatingIncomeLoss
Namespace Prefix: | cna_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The income earned from investments in securities and property, equipment and other capital assets. It includes rent from property and equipment, dividends from shares in corporations, and interest from bonds, loans, mortgages, derivatives, commercial paper, bank accounts, certificates of deposits, treasuries, and other financial securities. It also includes realized gains and losses on trading securities. + References No definition available. + Details
Name: | cna_NetInvestmentIncomeAndGainsLossesOnTradingSecurities
Namespace Prefix: | cna_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Net Operating Income (Loss) Attributable to Parent + References No definition available. + Details
Name: | cna_NetOperatingIncomeLossFromContinuingOperationsAttributabletoParent
Namespace Prefix: | cna_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Net realized investment gains (losses) + References No definition available. + Details
Name: | cna_NetRealizedInvestmentGainsLosses
Namespace Prefix: | cna_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Operating Income (Loss) before Income Tax + References No definition available. + Details
Name: | cna_OperatingIncomeLossFromContinuingOperationsBeforeIncomeTax
Namespace Prefix: | cna_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Operating Revenues + References No definition available. + Details
Name: | cna_OperatingRevenues
Namespace Prefix: | cna_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Other Insurance Related Expenses + References No definition available. + Details
Name: | cna_OtherInsuranceRelatedExpenses
Namespace Prefix: | cna_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27357-111563 + Details
Name: | us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The total amount of expense recognized during the period for future policy benefits, claims and claims adjustment costs, and for selling, general and administrative costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.5,6,7) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 + Details
Name: | us-gaap_BenefitsLossesAndExpenses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_BenefitsLossesAndExpensesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of amortization expense (reversal of expense) for deferred policy acquisition costs. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(7)(a)) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 30 -Section 35 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=95462302&loc=d3e10157-158409 Reference 3: 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 I)) -URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574960-122915 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 235 -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-18(Column I)) -URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e575016-122915 Reference 5: http://www.xbrl.org/2003/role/presentationRef -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 6: http://www.xbrl.org/2003/role/presentationRef -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 Amount after tax of income (loss) from continuing operations attributable to the parent. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.13) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=96868048&loc=SL4613673-111683 + Details
Name: | us-gaap_IncomeLossFromContinuingOperations
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of expense classified as other. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.7) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.4,6) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
Name: | us-gaap_OtherExpenses
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of revenue and income classified as other. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.4) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 + Details
Name: | us-gaap_OtherIncome
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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.5) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6480758&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 of expense for dividends to policyholders. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 50 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6483535&loc=d3e16392-158451 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.6) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 + Details
Name: | us-gaap_PolicyholderDividends
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/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.1) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.13(c)) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 235 -Section S99 -Paragraph 2 -Subparagraph (SX 210.12-17) -URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915 + 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/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (b) -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
- References No definition available. + Details
Name: | us-gaap_RevenuesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
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
- Details
Name: | us-gaap_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

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

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

X
- Details
Name: | us-gaap_ConsolidationItemsAxis=us-gaap_IntersegmentEliminationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |