Insurance (Reconciliation of Disclosure to Liability) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	$ 13,587
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	811
Total unpaid claims and allocated claims adjustment expense	14,398
Unallocated claims adjustment expenses	98
Discounting	(1,285)
Liability for unpaid claims and claim adjustment liabilities - short-duration	13,211
Liability for unpaid claims and claim adjustment liabilities - long-duration	6,005
Liability for Claims and Claims Adjustment Expense	19,216	$ 17,788	$ 17,094	$ 16,157
U.S.
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	10,539
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	215
Latin America
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	390
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	25
Group Life - Term
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	2,057
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	13
Group Life - Term | Asia
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	627
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	238
Group Long-Term Disability
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	7,091
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	133
Discounting	(1,200)	$ (1,300)
Property & Casualty - Auto
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	1,162
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	68
Property & Casualty - Home
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	229
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	1
Protection Life
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	317
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	7
Protection Health
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	73
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	18
Other insurance lines - all segments combined
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	2,031
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	$ 333