Securities (Details Textual) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Interest Receivable	$ 36,700		$ 36,700
Trading	2,612		2,612		$ 2,179
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Period Increase (Decrease)		$ 0		$ 0
Debt Securities, Available-for-sale	423,478		423,478		426,424
Debt Securities, Available-for-Sale, Accrued Interest Writeoff	0		0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	0		0
Debt Securities, Available-for-sale, Realized Gain (Loss)	0	0	0	(1,500)
Debt Securities, Available-for-sale, Past due	0		0
Debt Securities, Available-for-sale, Nonaccrual	0		0
Debt Securities, Held-to-maturity, Past Due	0		0
Debt Securities, Held-to-maturity, Nonaccrual	0		0
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held					0
Securities (Textual) [Abstract]
Callable Securities in Investment Portfolio	3,900		3,900
Pledged Financial Instruments, Not Separately Reported, Securities	417,100		417,100		375,500
Investments in obligations of individual states, counties or municipalities which exceed 10% of equity	0		0		0
Debt Securities, Held-to-maturity	659,573		659,573		740,806
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	0		0
Debt Securities, Available-for-Sale, Accrued Interest Writeoff	0		0
Debt Securities, Available-for-sale, Realized Gain (Loss)	0	0	0	1,500
Debt Securities, Held-to-maturity, Allowance for Credit Loss, Period Increase (Decrease)	0		0
Debt Securities, Held-to-Maturity, Accrued Interest, Writeoff	0		0
Debt Securities, Held-to-maturity, Sold, Realized Gain (Loss)	0	$ 0	0	$ 0
Equity Securities, FV-NI	21,119		21,119		$ 21,261
Available-for-sale Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Interest Receivable	1,400		1,400
Held-to-maturity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Interest Receivable	$ 1,700		$ 1,700