Securities (Details Textual) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Interest Receivable	$ 32,900		$ 32,900
Trading	2,541		2,541		$ 2,179
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Period Increase (Decrease)		$ 0		$ 0
Debt Securities, Available-for-sale	420,517		420,517		426,424
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	4,100		4,100
Pledged Financial Instruments, Not Separately Reported, Securities	431,800		431,800		375,500
Investments in obligations of individual states, counties or municipalities which exceed 10% of equity	0		0		0
Debt Securities, Held-to-maturity	731,026		731,026		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	1,462	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	20,810		20,810		$ 21,261
Available-for-sale Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Interest Receivable	1,300		1,300
Held-to-maturity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Interest Receivable	$ 1,800		$ 1,800