Fair Value Measurements - Quantitative information about the significant unobservable inputs (Details) - Level 3	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Discount rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques
Probability (as a percent)	8.57		9.02
Basis point for adjustment of discount rate	1
Fair value increase (decrease)	$ (407,000)
Probability (as a percent)	0.0857	0.0902
Basis point for adjustment of discount rate for non-hybrid instruments	1
Fair value increase (decrease) for non-hybrid investments	$ 541,000
Discount rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques
Probability (as a percent)	25.14		24.59
Basis point for adjustment of discount rate	1
Fair value increase (decrease)	$ 407,000
Probability (as a percent)	0.2714	0.2659
Basis point for adjustment of discount rate for non-hybrid instruments	1
Fair value increase (decrease) for non-hybrid investments	$ 555,000
Discount rate | Weighted average
Fair Value Measurement Inputs and Valuation Techniques
Probability (as a percent)	(25.14)		(24.59)
Fair value increase (decrease)		$ 0.2659
Probability (as a percent)	0.2714
Sale Proceeds | Minimum
Fair Value Measurement Inputs and Valuation Techniques
Amount of comparable TDPRV	$ 67,500,000		$ 67,500,000
Fair value increase (decrease)	(1,400,000)
Sale Proceeds | Maximum
Fair Value Measurement Inputs and Valuation Techniques
Amount of comparable TDPRV	350,000,000		350,000,000
Fair value increase (decrease)	10,800,000
Sale Proceeds | Weighted average
Fair Value Measurement Inputs and Valuation Techniques
Amount of comparable TDPRV	$ 100,000,000		$ 100,000,000
Timing of Cash Flows | Minimum
Fair Value Measurement Inputs and Valuation Techniques
Probability (as a percent)	0.59		0.10
Fair value increase (decrease)	$ (216,000)
Timing of Cash Flows | Maximum
Fair Value Measurement Inputs and Valuation Techniques
Probability (as a percent)	73.27		73.27
Fair value increase (decrease)	$ 1,500,000