Investment Securities - Net Gains on Non-marketable and Other Equity Securities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	$ 167,078	$ (15,110)
Non-marketable securities
Gain (Loss) on Securities [Line Items]
Less: realized net gains (losses) on sales of non-marketable and other equity securities	69,775	(49)
Net gains (losses) on non-marketable and other equity securities still held	97,303	(15,061)
Non-marketable securities | Fair value accounting | Consolidated venture capital and private equity fund investments
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	17,211	3,113
Non-marketable securities | Fair value accounting | Unconsolidated venture capital and private equity fund investments
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	12,510	1,252
Non-marketable securities | Fair value accounting | Other investments
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	13,769	(2,943)
Non-marketable securities | Equity method accounting | Consolidated venture capital and private equity fund investments
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	45,385	(8,046)
Non-marketable securities | Equity method accounting | Debt funds
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	414	(362)
Non-marketable securities | Equity method accounting | Other investments
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	228	(620)
Other equity securities | Fair value accounting
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	$ 77,561	$ (7,504)