Investments Fair Value Inputs, Assets, Quantitative Information (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Equity Securities without Readily Determinable Fair Value
Other investments, cost	$ 981,554
Available-for-sale Securities	985,458	$ 1,001,970
Limited Partner
Equity Securities without Readily Determinable Fair Value
Other investments, cost	9,532	7,568
Unrealized gain	225	2,236
Fair value	9,593	9,753
Unrealized loss	164	51
Certificates of Deposit
Equity Securities without Readily Determinable Fair Value
Certificates of Deposit, at Carrying Value	300	300
Other investments, cost	300	300
Unrealized gain	0	0
Unrealized loss	0	0
Short-term Investments
Equity Securities without Readily Determinable Fair Value
Unrealized gain	0	0
Fair value	37,702	199
Unrealized loss	1	0
Available-for-sale Securities	37,703	199
Other Long-term Investments
Equity Securities without Readily Determinable Fair Value
Other investments, cost	47,535	8,067
Unrealized gain	225	2,236
Unrealized loss	165	51
Total other investments	$ 47,595	$ 10,252

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
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Amount, after adjustment, of cost-method investment. Adjustments include, but are not limited to, dividends received in excess of earnings after date of investment that are considered a return of investment and other than temporary impairments.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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