Insurance and Contractholder Liabilities - Activity in Liabilities for Unpaid Claims and Claim Expenses (Details) - Intenational Markets and Group Disability and Life - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Liability for Claims and Claims Adjustment Expense [Line Items]
Beginning balance	$ 5,816
Beginning balance		$ 5,432
Less: Reinsurance and other amounts recoverable	184
Less: Reinsurance and other amounts recoverable		156
Beginning balance, net	5,632
Beginning balance, net		5,276
Incurred claims related to:
Current year	4,277	4,205
Prior years:
Interest accretion	118	117
All other incurred	(12)	(59)
Total incurred	4,383	4,263
Paid costs related to:
Current year	2,435	2,422
Prior years	1,702	1,594
Total paid	4,137	4,016
Foreign currency	5	(26)
Ending balance, net	5,883
Ending balance, net		5,497
Add: Reinsurance and other amounts recoverable	190
Add: Reinsurance and other amounts recoverable		171
Ending balance	$ 6,073
Ending balance		$ 5,668