Investment Securities - Nonmarketable Securities Under Equity Method Accounting (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Consolidated venture capital and private equity fund investments | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	$ 215,367	$ 129,485
Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund II, LP
Investment Holdings [Line Items]
Nonmarketable securities	3,612	4,670
Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund III, LP
Investment Holdings [Line Items]
Nonmarketable securities	15,668	17,396
Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund IV, LP
Investment Holdings [Line Items]
Nonmarketable securities	27,064	28,974
Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund V funds
Investment Holdings [Line Items]
Nonmarketable securities	46,830	28,189
Consolidated venture capital and private equity fund investments | Equity method accounting | CP II, LP
Investment Holdings [Line Items]
Nonmarketable securities	5,907	7,122
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	116,286	43,134
Debt funds | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	7,271	5,826
Debt funds | Equity method accounting | Gold Hill Capital 2008, LP (ii)
Investment Holdings [Line Items]
Nonmarketable securities	5,525	3,901
Debt funds | Equity method accounting | Other debt funds
Investment Holdings [Line Items]
Nonmarketable securities	1,746	1,925
Other investments | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	152,863	121,721
Other investments | Equity method accounting | SPD Silicon Valley Bank Co., Ltd.
Investment Holdings [Line Items]
Nonmarketable securities	74,190	76,412
Other investments | Equity method accounting | Other investments
Investment Holdings [Line Items]
Nonmarketable securities	$ 78,673	$ 45,309
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%