Investments - Short-term and Other Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Summary of Investment Holdings
Other investments	$ 282,866	$ 311,287
Related Parties
Summary of Investment Holdings
Other investments	231,593	238,841
Equity method investments
Summary of Investment Holdings
Other investments	136,935	143,511
Equity method investments | Related Parties
Summary of Investment Holdings
Other investments	100,809	109,612
Notes receivable
Summary of Investment Holdings
Other investments	130,832	129,299
Notes receivable | Related Parties
Summary of Investment Holdings
Other investments	130,784	129,229
Long-term Certificates of Deposit (CDs), at cost
Summary of Investment Holdings
Other investments	150	20,150
Investments, at fair value
Summary of Investment Holdings
Other investments	5,987	9,365
Investments, at cost or amortized cost
Summary of Investment Holdings
Other investments	$ 8,962	$ 8,962