Revenue from Contracts with Customers Revenue from Contracts with Customers (Reclassification of Bank Card Transaction Fees) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification of Bank Card Transaction Fees [Line Items]
Bank card transaction fees	$ 171,576	$ 155,100	$ 154,043
Non-interest income	501,341	461,263	446,556
Data processing and software	85,978	80,998	79,589
Other	64,304	63,366	59,499
Noninterest Expense	$ 737,821	744,343	689,229
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Reclassification of Bank Card Transaction Fees [Line Items]
Bank card transaction fees		180,441	181,879
Non-interest income		486,604	474,392
Data processing and software		92,246	92,722
Other		77,459	74,202
Noninterest Expense		769,684	717,065
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Reclassification of Bank Card Transaction Fees [Line Items]
Bank card transaction fees		(25,341)	(27,836)
Non-interest income		(25,341)	(27,836)
Data processing and software		(11,248)	(13,133)
Other		(14,093)	(14,703)
Noninterest Expense		(25,341)	(27,836)
Initial Application Period Cumulative Effect Transition [Domain]
Reclassification of Bank Card Transaction Fees [Line Items]
Bank card transaction fees		155,100	154,043
Non-interest income		461,263	446,556
Data processing and software		80,998	79,589
Other		63,366	59,499
Noninterest Expense		$ 744,343	$ 689,229