Revenue from Contracts with Customer (Revenue from Contracts with Customer) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Residential mortgage banking revenue, net	$ 31,484	$ 33,430	$ 103,085	$ 94,158
(Loss) gain on sale of investment securities, net	0	(6)	14	27
Unrealized holding losses on equity securities	(462)	0	(1,894)	0
Gain on loan sales, net	2,772	9,260	5,350	14,324
BOLI income	2,051	2,041	6,181	6,199
Remaining other income (a)	13,900		42,815
Other income	17,022		51,479
Total non-interest income	72,388	76,693	222,606	208,037
Account maintenance fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	4,283		12,606
Transaction-based and overdraft service charges
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	6,427		19,127
Debit/ATM interchange fees
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	4,864		14,356
Total service charges on deposits
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	15,574	15,849	46,089	46,056
Brokerage revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	3,947	$ 3,832	12,302	$ 11,857
Merchant fee income
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,158		3,220
Credit card and interchange income
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 1,964		$ 5,444

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