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Borrowings (Narrative) (Details) - USD ($) $ in Thousands		12 Months Ended
	Apr. 15, 2015	Dec. 31, 2018	Dec. 31, 2017
Short Term Debt [Line Items]
Short-term borrowings		$ 469,500	$ 446,200
Outstanding under unsecured federal funds purchased		$ 64,000
Short-term borrowings, weighted average rate		2.64%	1.50%
Subordinated Notes Due April 15, 2030 [Member]
Short Term Debt [Line Items]
Principal amount	$ 40,000
Interest rate	6.00%
Number of years at stated rate		10 years
Proceeds from issuance of debt, net		$ 38,900
Debt issuance costs		$ 1,100
Debt issuance cost amortization period		15 years
Subordinated Notes Due April 15, 2030 [Member] | LIBOR [Member]
Short Term Debt [Line Items]
Spread on variable rate	3.944%
Federal Home Loan Bank Overnight Borrowings [Member]
Short Term Debt [Line Items]
Short-term borrowings		$ 200,000	$ 304,700
Federal Home Loan Borrowings Short Term Advances [Member]
Short Term Debt [Line Items]
Short-term borrowings		$ 205,500	$ 141,500

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