Investment Securities - Summary of Venture Capital and Private Equity Fund Investments Held by Consolidated Funds and Percentage Ownership (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Fair value accounting \| Consolidated venture capital and private equity fund investments
Investment Holdings [Line Items]
Nonmarketable securities	$ 74,293	$ 87,180

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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