Investment Securities - Major Components of Non-marketable and Other Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Investments in qualified affordable housing projects, net	$ 458,476	$ 318,575
Total non-marketable and other securities	1,213,829	941,104
Consolidated venture capital and private equity fund investments | Fair value accounting
Investment Holdings [Line Items]
Nonmarketable securities	87,180	118,333
Consolidated venture capital and private equity fund investments | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	215,367	129,485
Unconsolidated venture capital and private equity fund investments | Fair value accounting
Investment Holdings [Line Items]
Nonmarketable securities	178,217		$ 201,098
Unconsolidated venture capital and private equity fund investments | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	215,367	129,485
Other investments | Fair value accounting
Investment Holdings [Line Items]
Nonmarketable securities	55,255	25,668
Other investments | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	152,863	121,721
Equity securities | Fair value accounting
Investment Holdings [Line Items]
Other equity securities	59,200	20,398
Debt funds | Equity method accounting
Investment Holdings [Line Items]
Nonmarketable securities	$ 7,271	$ 5,826