Financing Receivables - Allowance for Credit Losses (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020		Dec. 31, 2020
Rollforward of allowance for credit losses
Beginning balance	$ 68	$ 51	[1]
Provisions	(13)	19
Charge-offs	(7)	(4)
Recoveries	1
Other	2
Ending balance	51	71
Commercial Loans
Rollforward of allowance for credit losses
Beginning balance	66	51	[1]
Provisions	(14)	16
Charge-offs	(6)	(2)
Other	2
Ending balance	48	67
Financing receivables
Accrued interest on loans	13			$ 16
Consumer Loans
Rollforward of allowance for credit losses
Beginning balance	2	0	[1]
Provisions	1	3
Charge-offs	(1)	(2)
Recoveries	1
Ending balance	$ 3	4
Cumulative Effect, Period of Adoption, Adjustment
Rollforward of allowance for credit losses
Beginning balance		5
Cumulative Effect, Period of Adoption, Adjustment | Commercial Loans
Rollforward of allowance for credit losses
Beginning balance		2
Cumulative Effect, Period of Adoption, Adjustment | Consumer Loans
Rollforward of allowance for credit losses
Beginning balance		3
Cumulative Effect, Period of Adoption, Adjusted Balance
Rollforward of allowance for credit losses
Beginning balance		56
Cumulative Effect, Period of Adoption, Adjusted Balance | Commercial Loans
Rollforward of allowance for credit losses
Beginning balance		53
Cumulative Effect, Period of Adoption, Adjusted Balance | Consumer Loans
Rollforward of allowance for credit losses
Beginning balance		$ 3

[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.