Fair Value Measurements - Fair Values of Financial Assets and Liabilities, Including Derivative Financial Instruments (Details) $ in Thousands	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Estimated Fair Value	$ 2,022,605	$ 2,411,622
Trading investments	54,840	$ 54,481
Level 3  | Valuation Technique, Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Estimated Fair Value	2,910
Trading investments	54,840
Total	$ 57,750
Level 3  | Valuation Technique, Discounted Cash Flow | Minimum | Measurement Input, Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities	0.071
Residual Interests	0.071
Level 3  | Valuation Technique, Discounted Cash Flow | Minimum | Measurement Input, Default Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities	0.040
Residual Interests	0.040
Level 3  | Valuation Technique, Discounted Cash Flow | Maximum | Measurement Input, Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities	0.111
Residual Interests	0.111
Level 3  | Valuation Technique, Discounted Cash Flow | Maximum | Measurement Input, Default Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities	0.170
Residual Interests	0.170
Level 3  | Valuation Technique, Discounted Cash Flow | Weighted Average | Measurement Input, Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities	0.085
Residual Interests	0.085
Level 3  | Valuation Technique, Discounted Cash Flow | Weighted Average | Measurement Input, Default Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities	0.115
Residual Interests	0.115