Allowance for Expected Credit Losses (Details) - Changes in the Allowance for Expected Credit Losses on Contractholder Receivables (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Credit Loss [Abstract]
Contractholder receivables (net of the allowance for expected credit losses), balance, beginning of year	$ 4,599
Contractholder receivables (net of the allowance for expected credit losses), balance, end of period	4,634
Contractholder receivables, allowance for expected credit losses [Roll Forward]
Contractholder receivables, allowance for expected credit losses, beginning balance	20
Current period change for expected credit losses	0
Write-offs of uncollectible contractholder receivables	0
Contractholder receivables, allowance for expected credit losses, ending balance	$ 20