Financing Receivables (Allowance for Loan Losses) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020		Dec. 31, 2020
Commercial Loans
Rollforward of the allowance for loan losses
Beginning balance	$ 66	$ 51	[1]
Provision	(15)	13
Charge-offs	(3)	(1)
Other	2
Ending balance	50	65
Financing Receivables
Release of allowance as a result of reclassification to held for sale	14
Valuation allowance to record loans held for sale at lower of amortized cost or fair value	7
Accrued interest	19			$ 16
Commercial Loans | Cumulative Effect, Period of Adoption, Adjustment
Rollforward of the allowance for loan losses
Beginning balance		2
Commercial Loans | Cumulative Effect, Period of Adoption, Adjusted Balance
Rollforward of the allowance for loan losses
Beginning balance		53
Consumer Loans
Rollforward of the allowance for loan losses
Beginning balance	2	0	[1]
Provision	1	3
Charge-offs		(2)
Ending balance	3	4
Consumer Loans | Cumulative Effect, Period of Adoption, Adjustment
Rollforward of the allowance for loan losses
Beginning balance		3
Consumer Loans | Cumulative Effect, Period of Adoption, Adjusted Balance
Rollforward of the allowance for loan losses
Beginning balance		3
Total
Rollforward of the allowance for loan losses
Beginning balance	68	51	[1]
Provision	(14)	16
Charge-offs	(3)	(3)
Other	2
Ending balance	$ 53	69
Total | Cumulative Effect, Period of Adoption, Adjustment
Rollforward of the allowance for loan losses
Beginning balance		5
Total | Cumulative Effect, Period of Adoption, Adjusted Balance
Rollforward of the allowance for loan losses
Beginning balance		$ 56

[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.