Investment Securities - Carrying Value and Ownership Percentage of Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Consolidated venture capital and private equity fund investments | Fair value accounting
Investment Holdings [Line Items]
Nonmarketable securities	$ 108		$ 89
Consolidated venture capital and private equity fund investments | Fair value accounting | Strategic Investors Fund, LP
Investment Holdings [Line Items]
Nonmarketable securities	5		5
Consolidated venture capital and private equity fund investments | Fair value accounting | Capital Preferred Return Fund, LP
Investment Holdings [Line Items]
Nonmarketable securities	51		50
Consolidated venture capital and private equity fund investments | Fair value accounting | Growth Partners, LP
Investment Holdings [Line Items]
Nonmarketable securities	52		34
Consolidated venture capital and private equity fund investments | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	544		362
Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund II, LP
Investment Holdings [Line Items]
Nonmarketable securities	4		4
Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund III, LP
Investment Holdings [Line Items]
Nonmarketable securities	28		16
Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund IV, LP
Investment Holdings [Line Items]
Nonmarketable securities	36		25
Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund V funds
Investment Holdings [Line Items]
Nonmarketable securities	87		67
Consolidated venture capital and private equity fund investments | Equity method accounting | CP II, LP
Investment Holdings [Line Items]
Nonmarketable securities	8		8
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	381		242
Debt funds | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	7		5
Debt funds | Equity method accounting | Gold Hill Capital 2008, LP
Investment Holdings [Line Items]
Nonmarketable securities	5		4
Debt funds | Equity method accounting | Other debt funds
Investment Holdings [Line Items]
Nonmarketable securities	2		1
Other investments | Fair value accounting
Investment Holdings [Line Items]
Nonmarketable securities	79		61
Other investments | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	215		203
Other investments | Equity method accounting | SPD Silicon Valley Bank Co., Ltd.
Investment Holdings [Line Items]
Nonmarketable securities	115		115
Other investments | Equity method accounting | Other investments
Investment Holdings [Line Items]
Nonmarketable securities	$ 100		$ 88
Non-marketable securities | Consolidated venture capital and private equity fund investments | Fair value accounting | Strategic Investors Fund, LP
Investment Holdings [Line Items]
Percentage of ownership	12.60%	12.60%
Non-marketable securities | Consolidated venture capital and private equity fund investments | Fair value accounting | Capital Preferred Return Fund, LP
Investment Holdings [Line Items]
Percentage of ownership	20.00%	20.00%
Non-marketable securities | Consolidated venture capital and private equity fund investments | Fair value accounting | Growth Partners, LP
Investment Holdings [Line Items]
Percentage of ownership	33.00%	33.00%
Non-marketable securities | Consolidated venture capital and private equity fund investments | Equity method accounting | Strategic Investors Fund II, LP
Investment Holdings [Line Items]
Percentage of ownership	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]
Percentage of ownership	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]
Percentage of ownership	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]
Percentage of ownership	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]
Percentage of ownership	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]
Percentage of ownership	3.80%
Non-marketable securities | Debt funds | Equity method accounting | Direct ownership interest
Investment Holdings [Line Items]
Percentage of ownership	11.50%
Non-marketable securities | Debt funds | Equity method accounting | Indirect ownership interest
Investment Holdings [Line Items]
Percentage of ownership	4.00%
Non-marketable securities | Debt funds | Equity method accounting | Gold Hill Capital 2008, LP
Investment Holdings [Line Items]
Percentage of ownership	15.50%	15.50%
Non-marketable securities | Other investments | Equity method accounting | SPD Silicon Valley Bank Co., Ltd.
Investment Holdings [Line Items]
Percentage of ownership	50.00%	50.00%