Investment Securities (Securities With A Continuous Unrealized Losses Position) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	$ 384,677	$ 195,171
Less than 12 months, Unrealized Loss	(7,734)	(1,885)
12 months or more, Fair Value	132,424	136,126
12 months or more, Unrealized Loss	(7,695)	(4,009)
Total, Fair Value	517,101	331,297
Total, Unrealized Loss	(15,429)	(5,894)
State And Municipals [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	153,335	54,732
Less than 12 months, Unrealized Loss	(2,896)	(574)
12 months or more, Fair Value	26,941	28,723
12 months or more, Unrealized Loss	(2,548)	(1,312)
Total, Fair Value	180,276	83,455
Total, Unrealized Loss	(5,444)	(1,886)
Pass-Through Mortgage Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	19,588	10,172
Less than 12 months, Unrealized Loss	(513)	(81)
12 months or more, Fair Value	47,729	52,652
12 months or more, Unrealized Loss	(2,254)	(1,151)
Total, Fair Value	67,317	62,824
Total, Unrealized Loss	(2,767)	(1,232)
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	211,754	130,267
Less than 12 months, Unrealized Loss	(4,325)	(1,230)
12 months or more, Fair Value	57,754	54,751
12 months or more, Unrealized Loss	(2,893)	(1,546)
Total, Fair Value	269,508	185,018
Total, Unrealized Loss	$ (7,218)	$ (2,776)