Investment Securities - Net Gains on Non-marketable and Other Equity Securities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	$ 189	$ 190	$ 661	$ 210
Non-marketable securities
Gain (Loss) on Securities [Line Items]
Less: realized net gains (losses) on sales of non-marketable and other equity securities	(17)	5	110	6
Net gains on non-marketable and other equity securities still held	206	185	551	204
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	36	9	72	13
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	47	16	79	15
Non-marketable securities | Fair value accounting | Other investments
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	(2)	0	11	(4)
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	144	51	438	70
Non-marketable securities | Equity method accounting | Debt funds
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	0	0	2	0
Non-marketable securities | Equity method accounting | Other investments
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	3	1	6	(3)
Other equity securities | Fair value accounting
Gain (Loss) on Securities [Line Items]
Total net gains on non-marketable and other equity securities	$ (39)	$ 113	$ 53	$ 119