Investment Securities - Components of Non-marketable and Other Equity Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Investment Holdings [Line Items]
Investments in qualified affordable housing projects, net	$ 419,028	$ 318,575
Non-marketable and other equity securities	1,150,094	941,104
Fair value accounting | Consolidated venture capital and private equity fund investments
Investment Holdings [Line Items]
Nonmarketable securities	92,010	118,333
Fair value accounting | Unconsolidated venture capital and private equity fund investments
Investment Holdings [Line Items]
Nonmarketable securities	181,550	201,098
Fair value accounting | Equity securities
Investment Holdings [Line Items]
Other equity securities in public companies (fair value accounting)	56,081	20,398
Fair value accounting | Other investments
Investment Holdings [Line Items]
Nonmarketable securities	43,524	25,668
Equity method accounting | Consolidated venture capital and private equity fund investments
Investment Holdings [Line Items]
Nonmarketable securities	196,425	129,485
Equity method accounting | Unconsolidated venture capital and private equity fund investments
Investment Holdings [Line Items]
Nonmarketable securities	196,425	129,485
Equity method accounting | Debt funds
Investment Holdings [Line Items]
Nonmarketable securities	7,153	5,826
Equity method accounting | Other investments
Investment Holdings [Line Items]
Nonmarketable securities	$ 154,323	$ 121,721