Fair Value Measurement - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans on non-accrual status	120 days
Charges-off loans	120 days
Average effect of fair value of hypothetical 20% adverse change in expected credit loss rates (in percent)	8.00%
Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale	$ 647,200	$ 142,700
Loans held-for-investment	53,300	109,800
Notes receivable and residual certificates	$ 3,459	$ 8,288
Fair Value, Inputs, Level 3 | Notes Receivable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Average effect on fair value of a 100 basis point increase in discount rates (in percent)	0.57%	0.69%
Average effect on fair value of a 200 basis point increase in discount rates (in percent)	1.13%	1.37%
Fair Value, Inputs, Level 3 | Minimum | Discount rate | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trailing fees liability, measurement input	5.90%
Fair Value, Inputs, Level 3 | Minimum | Discount rate | Notes Receivable | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	5.79%	4.96%
Fair Value, Inputs, Level 3 | Minimum | Discount rate | Loans (at fair value) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	5.90%	3.42%
Fair Value, Inputs, Level 3 | Minimum | Credit risk rate | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trailing fees liability, measurement input	0.01%
Fair Value, Inputs, Level 3 | Minimum | Credit risk rate | Notes Receivable | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.81%	0.04%
Fair Value, Inputs, Level 3 | Minimum | Credit risk rate | Loans (at fair value) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	0.01%	0.08%
Fair Value, Inputs, Level 3 | Maximum | Discount rate | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trailing fees liability, measurement input	20.88%
Fair Value, Inputs, Level 3 | Maximum | Discount rate | Notes Receivable | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	20.35%	15.72%
Fair Value, Inputs, Level 3 | Maximum | Discount rate | Loans (at fair value) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	20.88%	16.49%
Fair Value, Inputs, Level 3 | Maximum | Credit risk rate | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Trailing fees liability, measurement input	93.09%
Fair Value, Inputs, Level 3 | Maximum | Credit risk rate | Notes Receivable | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	50.69%	50.69%
Fair Value, Inputs, Level 3 | Maximum | Credit risk rate | Loans (at fair value) | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loan receivable, measurement input	93.09%	55.79%