Investment Securities - Components of Non-marketable and Other Equity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Investment Holdings [Line Items]
Investments in qualified affordable housing projects, net	$ 560,983	$ 458,476
Non-marketable and other equity securities	1,547,363	1,213,829
Fair value accounting | Consolidated venture capital and private equity fund investments
Investment Holdings [Line Items]
Nonmarketable securities	74,293	87,180
Fair value accounting | Unconsolidated venture capital and private equity fund investments
Investment Holdings [Line Items]
Nonmarketable securities	152,367	178,217
Fair value accounting | Equity securities
Investment Holdings [Line Items]
Other equity securities in public companies (fair value accounting)	229,297	59,200
Fair value accounting | Other investments
Investment Holdings [Line Items]
Nonmarketable securities	56,008	55,255
Equity method accounting | Consolidated venture capital and private equity fund investments
Investment Holdings [Line Items]
Nonmarketable securities	274,721	215,367
Equity method accounting | Unconsolidated venture capital and private equity fund investments
Investment Holdings [Line Items]
Nonmarketable securities	274,721	215,367
Equity method accounting | Debt funds
Investment Holdings [Line Items]
Nonmarketable securities	6,918	7,271
Equity method accounting | Other investments
Investment Holdings [Line Items]
Nonmarketable securities	$ 192,776	$ 152,863