Investment Securities - Nonmarketable Securities Under Equity Method Accounting (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Consolidated venture capital and private equity fund investments | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	$ 362,192	$ 215,367
Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund II, LP
Investment Holdings [Line Items]
Nonmarketable securities	3,705	3,612
Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund III, LP
Investment Holdings [Line Items]
Nonmarketable securities	16,110	15,668
Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund IV, LP
Investment Holdings [Line Items]
Nonmarketable securities	25,169	27,064
Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund V funds
Investment Holdings [Line Items]
Nonmarketable securities	67,052	46,830
Consolidated venture capital and private equity fund investments | Equity method accounting | CP II, LP
Investment Holdings [Line Items]
Nonmarketable securities	7,887	5,907
Consolidated venture capital and private equity fund investments | Equity method accounting | Other venture capital and private equity fund investments
Investment Holdings [Line Items]
Nonmarketable securities	242,269	116,286
Debt funds | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	5,444	7,271
Debt funds | Equity method accounting | Gold Hill Capital 2008, LP (ii)
Investment Holdings [Line Items]
Nonmarketable securities	3,941	5,525
Debt funds | Equity method accounting | Other debt funds
Investment Holdings [Line Items]
Nonmarketable securities	1,503	1,746
Other investments | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	202,809	152,863
Other investments | Equity method accounting | SPD Silicon Valley Bank Co., Ltd.
Investment Holdings [Line Items]
Nonmarketable securities	115,232	74,190
Other investments | Equity method accounting | Other investments
Investment Holdings [Line Items]
Nonmarketable securities	$ 87,577	$ 78,673
Non-marketable securities | Consolidated venture capital and private equity fund investments | CP II, LP | Direct ownership interest
Investment Holdings [Line Items]
Ownership interest percentage	1.30%
Non-marketable securities | Consolidated venture capital and private equity fund investments | CP II, LP | Indirect ownership interest
Investment Holdings [Line Items]
Ownership interest percentage	3.80%
Non-marketable securities | Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund II, LP
Investment Holdings [Line Items]
Ownership interest percentage	8.60%	8.60%
Non-marketable securities | Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund III, LP
Investment Holdings [Line Items]
Ownership interest percentage	5.90%	5.90%
Non-marketable securities | Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund IV, LP
Investment Holdings [Line Items]
Ownership interest percentage	5.00%	5.00%
Non-marketable securities | Consolidated venture capital and private equity fund investments | Equity method accounting | CP II, LP
Investment Holdings [Line Items]
Ownership interest percentage	5.10%	5.10%
Non-marketable securities | Consolidated venture capital and private equity fund investments | Equity method accounting | CP II, LP | Direct ownership interest
Investment Holdings [Line Items]
Ownership interest percentage	1.30%
Non-marketable securities | Consolidated venture capital and private equity fund investments | Equity method accounting | CP II, LP | Indirect ownership interest
Investment Holdings [Line Items]
Ownership interest percentage	3.80%
Non-marketable securities | Debt funds | Equity method accounting | Direct ownership interest
Investment Holdings [Line Items]
Ownership interest percentage	11.50%
Non-marketable securities | Debt funds | Equity method accounting | Indirect ownership interest
Investment Holdings [Line Items]
Ownership interest percentage	4.00%
Non-marketable securities | Debt funds | Equity method accounting | Gold Hill Capital 2008, LP (ii)
Investment Holdings [Line Items]
Ownership interest percentage	15.50%	15.50%
Non-marketable securities | Other investments | Equity method accounting | SPD Silicon Valley Bank Co., Ltd.
Investment Holdings [Line Items]
Ownership interest percentage	50.00%	50.00%