Securities (Schedule of Securities Available-for-Sale) (Details) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 921,890,000	$ 834,850,000
Gross Unrealized Gains	40,506,000	21,780,000
Gross Unrealized Losses	(126,000)	(1,805,000)
Allowance for Credit Losses	0
Fair Value	962,270,000	854,825,000
Obligations of State and Political Subdivisions
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	387,562,000	307,943,000
Gross Unrealized Gains	24,612,000	16,366,000
Gross Unrealized Losses	(57,000)	(9,000)
Allowance for Credit Losses	0
Fair Value	412,117,000	324,300,000
MBS/CMO
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	534,328,000	526,907,000
Gross Unrealized Gains	15,894,000	5,414,000
Gross Unrealized Losses	(69,000)	(1,796,000)
Allowance for Credit Losses	0
Fair Value	$ 550,153,000	$ 530,525,000