Noninterest Income Client Investment Fees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Gains and Losses on Derivatives [Abstract]
Sweep Money Market Fees	$ 28,485	$ 15,147	$ 9,347
Investment Advisory, Management and Administrative Fees	16,831	15,389	12,263
Sweep Repo Fees	10,820	1,683	0
Asset Management Fees	$ 56,136	$ 32,219	$ 21,610