Securities (Schedule of Securities with Unrealized Losses) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months Fair Value	$ 669,283	$ 89,337
Less than 12 Months Unrealized Loss	(14,705)	(326)
12 Months or More Fair Value	0	0
12 Months or More Unrealized Loss	0	0
Total Fair Value	669,283	89,337
Total Unrealized Loss	(14,705)	(326)
Obligations of State and Political Subdivisions
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months Fair Value	155,320	10,652
Less than 12 Months Unrealized Loss	(2,547)	(103)
12 Months or More Fair Value	0	0
12 Months or More Unrealized Loss	0	0
Total Fair Value	155,320	10,652
Total Unrealized Loss	(2,547)	(103)
MBS/CMO
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months Fair Value	405,387	19,631
Less than 12 Months Unrealized Loss	(8,871)	(25)
12 Months or More Fair Value	0	0
12 Months or More Unrealized Loss	0	0
Total Fair Value	405,387	19,631
Total Unrealized Loss	(8,871)	(25)
US Gov't Sponsored Entities & Agencies
Debt Securities, Available-for-sale [Line Items]
Less than 12 Months Fair Value	108,576	59,054
Less than 12 Months Unrealized Loss	(3,287)	(198)
12 Months or More Fair Value	0	0
12 Months or More Unrealized Loss	0	0
Total Fair Value	108,576	59,054
Total Unrealized Loss	$ (3,287)	$ (198)