Fair Value Measurements - Investments - Schedule of Fair Value Measurements of Investments by Major Class (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Infrastructure Assets	$ 1,021,161	$ 983,552
Unrealized appreciation on foreign currency forward contracts	4,437	28
Unrealized depreciation on foreign currency forward contracts	(8,317)	(18,890)
Investments in Money Market Funds	613,549	278,417
Total Investments and Cash Equivalents, Estimated Fair Value	1,630,830	1,243,107
Level I
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Infrastructure Assets	0	0
Unrealized appreciation on foreign currency forward contracts	0	0
Unrealized depreciation on foreign currency forward contracts	0	0
Investments in Money Market Funds	613,549	278,417
Total Investments and Cash Equivalents, Estimated Fair Value	613,549	278,417
Level II
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Infrastructure Assets	0	0
Unrealized appreciation on foreign currency forward contracts	4,437	28
Unrealized depreciation on foreign currency forward contracts	(8,317)	(18,890)
Investments in Money Market Funds	0	0
Total Investments and Cash Equivalents, Estimated Fair Value	(3,880)	(18,862)
Level III
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Infrastructure Assets	1,021,161	983,552
Unrealized appreciation on foreign currency forward contracts	0	0
Unrealized depreciation on foreign currency forward contracts	0	0
Investments in Money Market Funds	0	0
Total Investments and Cash Equivalents, Estimated Fair Value	$ 1,021,161	$ 983,552