Fair Value - Schedule of Fair Value and Carrying Value of Company Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024	Jun. 30, 2024
Fair Value
Assets:
Finance receivables, net	$ 7,423,293	$ 7,342,319	$ 8,041,027
Liabilities:
Deposits, net	541,418	555,902	516,621
Fair Value | Medium-term notes
Debt:
Long-term debt, fair value	3,267,379	3,127,710	3,762,182
Fair Value | Senior notes
Debt:
Long-term debt, fair value	687,885	683,624	678,553
Fair Value | Asset-backed U.S. commercial paper conduit facility | Secured Debt
Debt:
Long-term debt, fair value	461,477	431,846	435,930
Fair Value | Asset-backed Canadian commercial paper conduit facility | Secured Debt
Debt:
Long-term debt, fair value	60,761	77,381	91,379
Fair Value | Asset-backed securitization debt | Secured Debt
Debt:
Long-term debt, fair value	1,877,186	1,955,006	1,918,596
Fair Value | Unsecured commercial paper
Debt:
Short-term debt, fair value	503,353	640,204	497,792
Carrying Value
Assets:
Finance receivables, net	7,326,222	7,288,294	8,018,564
Liabilities:
Deposits, net	537,884	550,586	504,093
Carrying Value | Medium-term notes
Debt:
Long-term debt, fair value	3,215,765	3,114,013	3,776,060
Carrying Value | Senior notes
Debt:
Long-term debt, fair value	747,164	746,800	746,438
Carrying Value | Asset-backed U.S. commercial paper conduit facility | Secured Debt
Debt:
Long-term debt, fair value	461,477	431,846	435,930
Carrying Value | Asset-backed Canadian commercial paper conduit facility | Secured Debt
Debt:
Long-term debt, fair value	60,761	77,381	91,379
Carrying Value | Asset-backed securitization debt | Secured Debt
Debt:
Long-term debt, fair value	1,866,214	1,950,138	1,921,408
Carrying Value | Unsecured commercial paper
Debt:
Short-term debt, fair value	$ 503,353	$ 640,204	$ 497,792