Amount of realized gain (loss) from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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

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

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Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

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Equity Investment - Narrative (Detail) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended		9 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Oct. 31, 2016	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]
Non-cash impairment charge				$ 0	$ 0	$ 76,800	$ 0
Proceeds from sale of equity investment						10,000	$ 0
October 2016 Investment \| Variable Interest Entity, Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Percentage of equity interest held	10.00%		10.00%
Equity investments			$ 10,000
Non-cash impairment charge		$ 5,300
Proceeds from sale of equity investment	$ 10,000
Gain on sale of investment						$ 5,300