Policy Claims and Benefits (Reconciliation of Claims Development to Liability) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	$ 641	$ 564	$ 433	$ 456
Short-duration Insurance Contract, Discounted Liability, Discount	101
Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Other Reconciling Item	2,447
Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Aggregate Reconciling Items	5,109
Liability for Claims and Claims Adjustment Expense	7,556	$ 6,786	$ 6,585	$ 5,896
Canada Segment Reporting Information [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Other Reconciling Item	90
EMEA [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Other Reconciling Item	587
Corporate And Other Segment Reporting Information [Member]
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Short-duration Insurance Contracts, Liability for Unpaid Claims and Claim Adjustment Expense, Other Reconciling Item	277
Life Insurance Product Line [Member]
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	1,594
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	12
Short-duration Insurance Contract, Discounted Liability, Discount for Reinsurance	(120)
Short-duration Insurance Contracts, Liability for Unpaid Claims and Claims Adjustment Expense, Accumulated Unallocated Claim Adjustment Expense	7
Life Insurance Product Line [Member] | Asia Pacific [Member]
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	806
Life Insurance Product Line [Member] | Americas [Member]
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	$ 788