Deposits (Summary of Deposits) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deposits [Abstract]
Non-interest bearing	$ 6,569,880	$ 6,792,497
NOW and interest bearing demand deposits	2,897,133	2,315,055
Wealth management deposits	2,996,764	2,323,699
Money market	5,704,866	4,515,353
Savings	2,665,194	2,829,373
Time certificates of deposit	5,260,841	4,407,370
Total deposits	$ 26,094,678	$ 23,183,347
Non-interest bearing	25.00%	29.00%
NOW and interest bearing demand deposits	11.00%	10.00%
Wealth management deposits	12.00%	10.00%
Money market	22.00%	20.00%
Savings	10.00%	12.00%
Time certificates of deposit	20.00%	19.00%
Total deposits	100.00%	100.00%