Investment Securities (Securities With A Continuous Unrealized Losses Position) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Fair Value	$ 414,075	$ 195,171
Less than 12 months, Unrealized Loss	(9,263)	(1,885)
12 months or more, Fair Value	83,024	136,126
12 months or more, Unrealized Loss	(6,550)	(4,009)
Total, Fair Value	497,099	331,297
Total, Unrealized Loss	(15,813)	(5,894)
State And Municipals [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Fair Value	175,087	54,732
Less than 12 months, Unrealized Loss	(4,533)	(574)
12 months or more, Fair Value	34,708	28,723
12 months or more, Unrealized Loss	(3,618)	(1,312)
Total, Fair Value	209,795	83,455
Total, Unrealized Loss	(8,151)	(1,886)
Pass-Through Mortgage Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Fair Value	51,251	10,172
Less than 12 months, Unrealized Loss	(886)	(81)
12 months or more, Fair Value	19,965	52,652
12 months or more, Unrealized Loss	(1,260)	(1,151)
Total, Fair Value	71,216	62,824
Total, Unrealized Loss	(2,146)	(1,232)
Collateralized Mortgage Obligations [Member]
Debt Securities, Available-for-sale [Line Items]
Less than 12 months, Fair Value	187,737	130,267
Less than 12 months, Unrealized Loss	(3,844)	(1,230)
12 months or more, Fair Value	28,351	54,751
12 months or more, Unrealized Loss	(1,672)	(1,546)
Total, Fair Value	216,088	185,018
Total, Unrealized Loss	$ (5,516)	$ (2,776)