Securities (Schedule of Securities with Unrealized Losses) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months Fair Value	$ 904,976	$ 89,337
Less than 12 Months Unrealized Loss	(17,449)	(326)
12 Months or More Fair Value	1,761	0
12 Months or More Unrealized Loss	(146)	0
Total Fair Value	906,737	89,337
Total Unrealized Loss	(17,595)	(326)
Obligations of State and Political Subdivisions
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months Fair Value	303,113	10,652
Less than 12 Months Unrealized Loss	(5,917)	(103)
12 Months or More Fair Value	1,452	0
12 Months or More Unrealized Loss	(143)	0
Total Fair Value	304,565	10,652
Total Unrealized Loss	(6,060)	(103)
MBS/CMO
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months Fair Value	475,726	19,631
Less than 12 Months Unrealized Loss	(8,404)	(25)
12 Months or More Fair Value	309	0
12 Months or More Unrealized Loss	(3)	0
Total Fair Value	476,035	19,631
Total Unrealized Loss	(8,407)	(25)
US Gov't Sponsored Entities & Agencies
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months Fair Value	126,137	59,054
Less than 12 Months Unrealized Loss	(3,128)	(198)
12 Months or More Fair Value	0	0
12 Months or More Unrealized Loss	0	0
Total Fair Value	126,137	59,054
Total Unrealized Loss	$ (3,128)	$ (198)