Finance Receivables, Net - Summary of Future Contractual Maturities of Gross Finance Receivables (Details) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018
Receivables [Abstract]
12 Months	[1]	$ 1,471	$ 1,543
24 Months		1,044	1,108
36 Months		705	755
48 Months		406	425
60 Months		152	158
Thereafter		17	14
Total		3,795	4,003
Amounts previously billed		$ 108	$ 107

[1] Includes amounts previously billed of $108 and $107 as of September 30, 2019 and December 31, 2018, respectively.