Financing Receivables (Allowance for Credit Losses) (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jan. 01, 2020	Dec. 31, 2019
Commercial loans [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit losses prior to adoption of credit loss standard	[1]						$ 20
Rollforward of the allowance for loan losses
Beginning balance					$ 20
Provisions		$ 11
Write-offs			$ 0
Ending balance		34	20	$ 34	20
Accrued interest on commercial loans		11		11			$ 11
Commercial loans [Member] | Cumulative effect of adoption of current expected credit losses guidance [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Cumulative effect of change in accounting policy						$ 3
Syndicated loans [Member]
Rollforward of the allowance for loan losses
Loans purchased		9	30	50	55
Loans sold		$ 0	$ 12	$ 7	$ 21

[1] Prior to January 1, 2020, the allowance for credit losses was based on an incurred loss model that did not require estimating expected credit losses over the expected life of the asset.