Investment Securities - Major Components of Non-marketable and Other Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Investment Holdings [Line Items]
Investments in qualified affordable housing projects, net	$ 616,188	$ 458,476
Total non-marketable and other securities	1,802,235	1,213,829
Consolidated venture capital and private equity fund investments | Fair value accounting
Investment Holdings [Line Items]
Nonmarketable securities	88,937	87,180
Consolidated venture capital and private equity fund investments | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	362,192	215,367
Unconsolidated venture capital and private equity fund investments | Fair value accounting
Investment Holdings [Line Items]
Nonmarketable securities	184,886	178,217
Unconsolidated venture capital and private equity fund investments | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	362,192	215,367
Other investments | Fair value accounting
Investment Holdings [Line Items]
Nonmarketable securities	60,975	55,255
Other investments | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	202,809	152,863
Equity securities | Fair value accounting
Investment Holdings [Line Items]
Other equity securities	280,804	59,200
Debt funds | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	$ 5,444	$ 7,271