Investment Securities (Available-for-sale And Held-to-maturity Securities, Continuous Unrealized Loss Position) (Details) $ in Thousands	Dec. 31, 2019 USD ($) item security	Dec. 31, 2018 USD ($) item security
Available-for-sale, continuous unrealized loss position [Abstract]
Number of securities | security	123	249
Available-for-sale, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months, Fair Value	$ 259,287	$ 294,474
12 months or longer, Fair Value	155,022	739,664
Total, Fair Value	414,309	1,034,138
Available-for-sale, continuous unrealized loss position, Unrealized losses [Abstract]
Less than 12 months, Unrealized losses	(647)	(3,323)
12 months or longer, Unrealized losses	(1,519)	(17,480)
Total, Unrealized losses	$ (2,166)	$ (20,803)
Held-to-maturity, continuous unrealized loss position [Abstract]
Number of securities | item	1	1
Held-to-maturity, continuous unrealized loss position, Fair Value [Abstract]
12 months or longer, Fair Value	$ 7,152	$ 7,278
Total, Fair Value	7,152	7,278
Held-to-maturity, continuous unrealized loss position, Unrealized losses [Abstract]
12 months or longer, Unrealized losses	(2,067)	(1,890)
Total, Unrealized losses	$ (2,067)	$ (1,890)
U.S. Government Agency Securities [Member]
Available-for-sale, continuous unrealized loss position [Abstract]
Number of securities | security	5	10
Available-for-sale, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months, Fair Value	$ 12,214	$ 679
12 months or longer, Fair Value	3,986	41,719
Total, Fair Value	16,200	42,398
Available-for-sale, continuous unrealized loss position, Unrealized losses [Abstract]
Less than 12 months, Unrealized losses	(44)	(2)
12 months or longer, Unrealized losses	(133)	(877)
Total, Unrealized losses	$ (177)	$ (879)
Asset-backed Securities [Member]
Available-for-sale, continuous unrealized loss position [Abstract]
Number of securities | security	28	26
Available-for-sale, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months, Fair Value	$ 115,909	$ 148,753
12 months or longer, Fair Value	56,427	11,506
Total, Fair Value	172,336	160,259
Available-for-sale, continuous unrealized loss position, Unrealized losses [Abstract]
Less than 12 months, Unrealized losses	(275)	(1,230)
12 months or longer, Unrealized losses	(260)	(122)
Total, Unrealized losses	$ (535)	$ (1,352)
Tax-exempt Obligations Of States And Political Subdivisions [Member]
Available-for-sale, continuous unrealized loss position [Abstract]
Number of securities | security		3
Available-for-sale, continuous unrealized loss position, Fair Value [Abstract]
12 months or longer, Fair Value		$ 3,625
Total, Fair Value		3,625
Available-for-sale, continuous unrealized loss position, Unrealized losses [Abstract]
12 months or longer, Unrealized losses		(45)
Total, Unrealized losses		$ (45)
Taxable obligations of states and political subdivisions [Member]
Available-for-sale, continuous unrealized loss position [Abstract]
Number of securities | security		22
Available-for-sale, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months, Fair Value		$ 4,492
12 months or longer, Fair Value		35,599
Total, Fair Value		40,091
Available-for-sale, continuous unrealized loss position, Unrealized losses [Abstract]
Less than 12 months, Unrealized losses		(19)
12 months or longer, Unrealized losses		(501)
Total, Unrealized losses		$ (520)
Residential Mortgage-backed Securities [Member]
Available-for-sale, continuous unrealized loss position [Abstract]
Number of securities | security	64	118
Available-for-sale, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months, Fair Value	$ 58,682	$ 17,168
12 months or longer, Fair Value	73,311	302,407
Total, Fair Value	131,993	319,575
Available-for-sale, continuous unrealized loss position, Unrealized losses [Abstract]
Less than 12 months, Unrealized losses	(114)	(49)
12 months or longer, Unrealized losses	(987)	(8,057)
Total, Unrealized losses	$ (1,101)	$ (8,106)
Collateralized Mortgage Obligation Securities [Member]
Available-for-sale, continuous unrealized loss position [Abstract]
Number of securities | security	22	44
Available-for-sale, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months, Fair Value	$ 37,387	$ 1,522
12 months or longer, Fair Value	18,136	193,355
Total, Fair Value	55,523	194,877
Available-for-sale, continuous unrealized loss position, Unrealized losses [Abstract]
Less than 12 months, Unrealized losses	(85)	(3)
12 months or longer, Unrealized losses	(123)	(3,991)
Total, Unrealized losses	$ (208)	$ (3,994)
Commercial Mortgage-backed Securities [Member]
Available-for-sale, continuous unrealized loss position [Abstract]
Number of securities | security	4	26
Available-for-sale, continuous unrealized loss position, Fair Value [Abstract]
Less than 12 months, Fair Value	$ 35,095	$ 121,860
12 months or longer, Fair Value	3,162	151,453
Total, Fair Value	38,257	273,313
Available-for-sale, continuous unrealized loss position, Unrealized losses [Abstract]
Less than 12 months, Unrealized losses	(129)	(2,020)
12 months or longer, Unrealized losses	(16)	(3,887)
Total, Unrealized losses	$ (145)	$ (5,907)
Single Issuers [Member]
Held-to-maturity, continuous unrealized loss position [Abstract]
Number of securities | item	1	1
Held-to-maturity, continuous unrealized loss position, Fair Value [Abstract]
12 months or longer, Fair Value	$ 7,152	$ 7,278
Total, Fair Value	7,152	7,278
Held-to-maturity, continuous unrealized loss position, Unrealized losses [Abstract]
12 months or longer, Unrealized losses	(2,067)	(1,890)
Total, Unrealized losses	$ (2,067)	$ (1,890)