Insurance and Contractholder Liabilities - Other Segments - Activity in Liabilities for Unpaid Claims and Claims Expenses (Details) - Intenational Markets and Group Disability and Life [Member] - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Liability For Unpaid Claims And Claims Adjustment Expense [Line Items]
Beginning balance, unpaid claims, gross	$ 5,432	$ 5,274
Less: Reinsurance and other amounts recoverable	156	140
Beginning balance, unpaid claims, net	5,276	5,134
Incurred claims related to:
Current year	4,205	4,046
Interest accretion	117	115
All other prior years	(59)	(161)
Total incurred	4,263	4,000
Paid claims related to:
Current year	2,422	2,383
Prior years	1,594	1,561
Total paid	4,016	3,944
Foreign currency	(26)	(16)
Ending balance, unpaid claims, net	5,497	5,174
Add: Reinsurance and other amounts recoverable	171	141
Ending balance, unpaid claims, gross	$ 5,668	$ 5,315