Marketable Securities and Equity Investments - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Summary of cash, cash equivalents and marketable securities
Cash	$ 3,300,000,000	$ 2,800,000,000
Other-than-temporary declines in fair value of available-for-sale debt securities	0	0	$ 0
Net unrealized gains	17,100,000	136,200,000	143,200,000
Weighted-average cost basis	69,400,000	51,400,000
Publicly Traded Companies Sale
Summary of cash, cash equivalents and marketable securities
Proceeds received	0	437,600,000	94,900,000
Weighted-average cost basis		$ 103,300,000	$ 29,800,000
Other assets
Summary of cash, cash equivalents and marketable securities
Equity securities without readily determinable fair value, amount	$ 85,800,000