Securities (Details Textual) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Interest Receivable	$ 33,400		$ 25,900
Trading	3,269	$ 2,838
Debt Securities, Available-for-sale	600,213	412,860
Debt Securities, Held-to-maturity, Past Due	0	0
Debt Securities, Available-for-sale, Past due	0	0
Investments in obligations of individual states, counties or municipalities which exceed 10% of equity	0	0
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
Securities (Textual) [Abstract]
Callable Securities in Investment Portfolio	3,300
Pledged Financial Instruments, Not Separately Reported, Securities	420,200	419,600
Investments in obligations of individual states, counties or municipalities which exceed 10% of equity	0	0
Debt Securities, Held-to-maturity	805,529	724,512
Equity Securities, FV-NI	22,419	22,107
Available-for-sale Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Interest Receivable	2,000	1,200
Held-to-maturity Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Interest Receivable	$ 1,600	$ 1,500