Financing Receivables (Allowance for Loan Losses) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019	Dec. 31, 2019
Commercial Loan [Member]
Rollforward of the allowance for loan losses
Beginning balance				$ 51	[1]	$ 49
Provision for Loan, Lease, and Other Losses		$ 16				6
Write-offs		2	$ (2)
Ending balance		67	53	67		53
Accrued interest		17		17			$ 14
Commercial Loan [Member] | Cumulative Effect, Period of Adoption, Adjustment
Rollforward of the allowance for loan losses
Beginning balance				2
Commercial Loan [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Rollforward of the allowance for loan losses
Beginning balance				53
Consumer Loan [Member]
Rollforward of the allowance for loan losses
Beginning balance	[1]			0
Provision for Loan, Lease, and Other Losses		3
Write-offs		(2)
Ending balance		4		4
Consumer Loan [Member] | Cumulative Effect, Period of Adoption, Adjustment
Rollforward of the allowance for loan losses
Beginning balance				3
Consumer Loan [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Rollforward of the allowance for loan losses
Beginning balance				3
Total Segment [Member]
Rollforward of the allowance for loan losses
Beginning balance	[1]			51
Provision for Loan, Lease, and Other Losses		19
Write-offs		(4)
Ending balance		71		71
Total Segment [Member] | Cumulative Effect, Period of Adoption, Adjustment
Rollforward of the allowance for loan losses
Beginning balance				5
Total Segment [Member] | Cumulative Effect, Period of Adoption, Adjusted Balance [Member]
Rollforward of the allowance for loan losses
Beginning balance				56
Syndicated loans [Member]
Rollforward of the allowance for loan losses
Loans purchased		96	52	165		126
Loans sold		5	$ 13	12		$ 40
Residential Mortgage [Member]
Rollforward of the allowance for loan losses
Loans purchased		$ 0		$ 22

[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.