Investment Securities - Summary of Venture Capital and Private Equity Fund Investments Held by Consolidated Funds and Percentage Ownership (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair value accounting \| Consolidated venture capital and private equity fund investments
Investment Holdings [Line Items]
Nonmarketable securities	$ 96,016	$ 88,937

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