Investments (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Investments [Abstract]
Equity method investments	$ 80,500,000		$ 79,600,000
Investments in marketable equity securities	0		0
Gain (loss) on marketable equity securities	0
Unrealized gain (loss) on marketable equity securities		$ 4,300,000
Investments in non-marketable equity securities	41,500,000		$ 42,700,000
Impairment charge on non-marketable equity security	$ 1,200,000