Noninterest Income - Summary of Noninterest Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summary of noninterest income [Abstract]
Gains on investment securities, net									$ 88,094	$ 64,603	$ 51,740
Gains on equity warrant assets, net									89,142	54,555	37,892	[1]
Foreign exchange fees									138,812	115,760	104,183
Credit card fees									94,072	76,543	68,205
Deposit service charges									76,097	58,715	52,524
Client investment fees									130,360	56,136	32,219
Lending related fees									41,949	43,265	33,395
Letters of credit and standby letters of credit fees									34,600	28,544	25,644
Other									51,858	59,110	50,750	[1]
Noninterest income	$ 186,707	$ 210,070	$ 192,689	$ 155,518	$ 152,266	$ 158,778	$ 128,528	$ 117,659	$ 744,984	$ 557,231	$ 456,552

[1] Our consolidated statements of income for the year ended December 31, 2016 was modified from prior periods’ presentation to conform to the current period's presentation, which reflects a new line item to separately disclose net gains on equity warrant assets. In prior periods, net gains on equity warrant assets were reported as a component of net gains on derivative instruments. We removed the line item "gains on derivative instruments, net" and reclassified all other gains on derivative instruments, net to other noninterest income.