Finance Receivables, Net - Summary of Future Contractual Maturities of Gross Finance Receivables (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Receivables [Abstract]
12 Months	[1]	$ 1,514	$ 1,543
24 Months		1,057	1,108
36 Months		715	755
48 Months		405	425
60 Months		151	158
Thereafter		18	14
Total		3,860	4,003
Amounts previously billed		$ 112	$ 107

[1] Includes amounts previously billed of $112 and $107 as of June 30, 2019 and December 31, 2018, respectively.