Other Investments - Investments without Readily Determinable Fair Value (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Investments, All Other Investments [Abstract]
Cost	$ 8,500,000	$ 8,500,000		$ 8,500,000
Cumulative unrealized gains	41,900,000	41,900,000		41,900,000
Carrying amount	50,400,000	50,400,000	$ 50,400,000	$ 50,400,000	$ 50,400,000	$ 50,400,000	$ 50,400,000
Upward adjustments	$ 0	$ 0