Securities (Schedule of Securities Available-for-Sale) (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 838,923,000	$ 834,850,000
Gross Unrealized Gains	36,889,000	21,780,000
Gross Unrealized Losses	(25,000)	(1,805,000)
Allowance for Credit Losses	0
Fair Value	875,787,000	854,825,000
Obligations of State and Political Subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	309,059,000	307,943,000
Gross Unrealized Gains	17,830,000	16,366,000
Gross Unrealized Losses	(25,000)	(9,000)
Allowance for Credit Losses	0
Fair Value	326,864,000	324,300,000
MBS/CMO
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	529,864,000	526,907,000
Gross Unrealized Gains	19,059,000	5,414,000
Gross Unrealized Losses	0	(1,796,000)
Allowance for Credit Losses	0
Fair Value	$ 548,923,000	$ 530,525,000