Rendering

Component: (Network and Table)
Network
2433411 - Disclosure - Benefit Plans (Estimated Future Minimum Benefit Payments to Participants) (Details)
(http://www.cna.com/role/BenefitPlansEstimatedFutureMinimumBenefitPaymentsToParticipantsDetails)
TableSchedule of Defined Benefit Plans Disclosures [Table]
Slicers (applies to each fact value in each table cell)
Reporting Entity [Axis]0000021175 (http://www.sec.gov/CIK)
Defined Benefit Plan Disclosure [Line Items]Period [Axis]
2016-12-31
Defined Benefit Plans and Other Postretirement Benefit Plans [Axis]
Pension Plans, Defined Benefit [Member]Other Postretirement Benefit Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payments in Year One
178,000,000  
3,000,000  
Defined Benefit Plan, Expected Future Benefit Payments in Year Two
178,000,000  
2,000,000  
Defined Benefit Plan, Expected Future Benefit Payments in Year Three
177,000,000  
2,000,000  
Defined Benefit Plan, Expected Future Benefit Payments in Year Four
178,000,000  
2,000,000  
Defined Benefit Plan, Expected Future Benefit Payments in Year Five
178,000,000  
2,000,000  
Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter
883,000,000  
3,000,000