Reserve for Property-Liability Insurance Claims and Claims Expense (Details 5) $ in Millions	Dec. 31, 2016 USD ($)
Claims Development [Line Items]
Net outstanding liabilities:	$ 19,066
Unallocated loss adjustment expenses	933
Reinsurance recoverable:	6,184
Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Other Reconciling Item	2
Gross reserve for property-liability insurance claims and claims expense	25,250
Discontinued Lines and Coverages
Claims Development [Line Items]
Net outstanding liabilities:	1,382
Reinsurance recoverable:	508
Gross reserve for property-liability insurance claims and claims expense	800
Auto insurance
Claims Development [Line Items]
Net outstanding liabilities:	12,961
Reinsurance recoverable:	5,422
Homeowners insurance
Claims Development [Line Items]
Net outstanding liabilities:	1,861
Reinsurance recoverable:	9
Other personal lines
Claims Development [Line Items]
Net outstanding liabilities:	1,310
Reinsurance recoverable:	212
Commercial lines
Claims Development [Line Items]
Net outstanding liabilities:	597
Reinsurance recoverable:	21
Other business lines
Claims Development [Line Items]
Net outstanding liabilities:	22
Reinsurance recoverable:	$ 10