Variable Interest Entities - Carrying Amount of Consolidated VIEs (Details) - USD ($) $ in Millions	Sep. 30, 2023		Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022		Jun. 30, 2022	Dec. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 1,190			$ 498	$ 536
Net finance receivables	21,067			19,986
Allowance for finance receivable losses	2,449		$ 2,392	2,311	2,255		$ 2,127	$ 2,095
Restricted cash and restricted cash equivalents	580	[1]		461	$ 483	[1]
Other assets	1,198			1,154				$ 1,019	$ 1,075
Long-term debt	19,851			18,281
Consolidated VIEs
Variable Interest Entity [Line Items]
Cash and cash equivalents	2			2
Net finance receivables	13,229			10,432
Allowance for finance receivable losses	1,480			1,126
Restricted cash and restricted cash equivalents	564			442
Other assets	30			28
Long-term debt	11,917			9,361
Other liabilities	$ 27			$ 20

[1] Restricted cash and restricted cash equivalents primarily represent funds required to be used for future debt payments relating to our secured transactions.