Noninterest Income Summary of Noninterest Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Summary of noninterest income [Abstract]
Gains on investment securities, net									$ 64,603	$ 51,740	$ 89,445
Noninterest Income	$ 152,266	$ 158,778	$ 128,528	$ 117,659	$ 113,502	$ 144,140	$ 112,776	$ 86,134	557,231	456,552	472,794
Gains on derivative instruments, net									54,555	37,892	70,963
Foreign exchange fees									115,760	104,183	87,007
Credit card fees									76,543	68,205	56,657
Deposit service charges									58,715	52,524	46,683
Asset Management Fees									56,136	32,219	21,610
Fees and Commissions									43,265	33,395	32,536
Letters of credit and standby letters of credit fees									28,544	25,644	20,889
Other									$ 59,110	$ 50,750	$ 47,004