Fair Value Measurements - Adjustments to the carrying value of investments (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Adjustments to the carrying value of these investments
Balance, beginning of year	$ 19,088	$ 20,477	$ 19,771	$ 20,376
Upward adjustments	1,525	101	1,631	202
Impairments and downward adjustments		(672)	(789)	(672)
Balance, end of year	20,613	$ 19,906	20,613	$ 19,906
Other Assets
Equity Securities without Readily Determinable Fair Value
Other equity investments	$ 61,100		$ 61,100		$ 36,600

Amount of equity investments other than securities.

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Amount of impairment loss and downward price adjustments on investment in equity security without readily determinable fair value.

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- Definition

Amount of upward adjustments of investment in equity security without readily determinable fair value.

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Amount of investment in equity security without readily determinable fair value.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116654751&loc=SL75117539-209714

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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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