Investment Securities - Non-marketable and Other Securities Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) Investment	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) Investment
Investment Holdings [Line Items]
Investments in qualified affordable housing projects, net	$ 339,900		$ 318,575
Tax credits and other tax benefits recognized	9,257	$ 5,422
Amortization expense included in provision for income taxes	7,636	$ 4,792
Other liabilities	223,206		205,685
Fair value accounting | Unconsolidated venture capital and private equity fund investments
Investment Holdings [Line Items]
Nonmarketable securities	$ 196,049		$ 201,098
Upper Limit
Investment Holdings [Line Items]
Percentage of ownership	5.00%
Non-marketable securities | Fair value accounting | Unconsolidated venture capital and private equity fund investments
Investment Holdings [Line Items]
Number of investments | Investment	212		213