Investment Securities (Schedule Of Investment Securities Classified As Available-for-sale And Held-to-maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Available-for-sale [Abstract]
Total	$ 1,039,150	$ 1,181,906
Gross unrealized gains	20,115	32,754
Gross unrealized losses	(5,042)	(8,496)
Investment securities available-for-sale	1,054,223	1,206,164
U.S. Government Agency Securities [Member]
Available-for-sale [Abstract]
Total	37,489	44,960
Gross unrealized gains	1,680	2,357
Gross unrealized losses	(49)	(120)
Investment securities available-for-sale	39,120	47,197
Asset-backed Securities [Member]
Available-for-sale [Abstract]
Total	368,502	238,678
Gross unrealized gains	481	143
Gross unrealized losses	(70)	(460)
Investment securities available-for-sale	368,913	238,361
Federally insured student loan securities [Member]
Available-for-sale [Abstract]
Total	24,709	28,013
Gross unrealized gains	85	38
Gross unrealized losses	(14)	(93)
Investment securities available-for-sale	24,780	27,958
Collateralized Loan Obligations Securities [Member]
Available-for-sale [Abstract]
Total	343,793	210,665
Gross unrealized gains	396	105
Gross unrealized losses	(56)	(367)
Investment securities available-for-sale	344,133	210,403
Tax-exempt Obligations Of States And Political Subdivisions [Member]
Available-for-sale [Abstract]
Total	3,559	4,042
Gross unrealized gains	181	248
Investment securities available-for-sale	3,740	4,290
Taxable Obligations Of States And Political Subdivisions [Member]
Available-for-sale [Abstract]
Total	46,013	47,884
Gross unrealized gains	3,044	4,180
Investment securities available-for-sale	49,057	52,064
Residential Mortgage-backed Securities [Member]
Available-for-sale [Abstract]
Total	193,037	256,914
Gross unrealized gains	6,442	9,765
Gross unrealized losses	(209)	(96)
Investment securities available-for-sale	199,270	266,583
Collateralized Mortgage Obligation Securities [Member]
Available-for-sale [Abstract]
Total	74,628	145,260
Gross unrealized gains	1,715	3,281
Gross unrealized losses	(1)	(11)
Investment securities available-for-sale	76,342	148,530
Commercial Mortgage-backed Securities [Member]
Available-for-sale [Abstract]
Total	305,922	359,125
Gross unrealized gains	6,572	12,717
Gross unrealized losses	(1,218)	(4,562)
Investment securities available-for-sale	311,276	367,280
Corporate Debt Securities [Member]
Available-for-sale [Abstract]
Total	10,000	85,043
Gross unrealized gains		63
Gross unrealized losses	(3,495)	(3,247)
Investment securities available-for-sale	$ 6,505	$ 81,859