Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Lower Limit
Significant Accounting Policies [Line Items]
Term of contract on forward contracts	1 year
Upper Limit
Significant Accounting Policies [Line Items]
Ownership interest percentage	5.00%	5.00%
Term of contract on forward contracts	5 years
Equity warrant assets (public portfolio) | Lower Limit
Significant Accounting Policies [Line Items]
Duration of the sale restrictions	3 months
Equity warrant assets (public portfolio) | Upper Limit
Significant Accounting Policies [Line Items]
Duration of the sale restrictions	6 months
Equity warrant assets (public portfolio) | Sales restrictions discount | Lower Limit
Significant Accounting Policies [Line Items]
Sales restriction discounts	0.10
Equity warrant assets (public portfolio) | Sales restrictions discount | Upper Limit
Significant Accounting Policies [Line Items]
Sales restriction discounts	0.20
Non-marketable securities | Other investments | SPD Silicon Valley Bank Co., Ltd. | Equity method investee
Significant Accounting Policies [Line Items]
Ownership interest percentage	50.00%
Non-marketable securities | Lower Limit | Consolidated venture capital and private equity fund investments | Equity method investee
Significant Accounting Policies [Line Items]
Ownership interest percentage	20.00%
Non-marketable securities | Lower Limit | Investments in limited partnerships | Equity method investee
Significant Accounting Policies [Line Items]
Ownership interest percentage	5.00%
Non-marketable securities | Fair value accounting | Consolidated venture capital and private equity fund investments | Growth Partners, LP
Significant Accounting Policies [Line Items]
Ownership interest percentage	33.00%	33.00%
Non-marketable securities | Fair value accounting | Consolidated venture capital and private equity fund investments | Capital Preferred Return Fund, LP
Significant Accounting Policies [Line Items]
Ownership interest percentage	20.00%	20.00%
Non-marketable securities | Fair value accounting | Consolidated venture capital and private equity fund investments | Strategic Investors Fund, LP
Significant Accounting Policies [Line Items]
Ownership interest percentage	12.60%	12.60%
Non-marketable securities | Fair value accounting | Consolidated venture capital and private equity fund investments | CP I, LP
Significant Accounting Policies [Line Items]
Ownership interest percentage	10.70%	10.70%