Investment Securities (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule of Available-for-sale Securities [Line Items]
AFS securities pledged as collateral	$ 433,200,000		$ 433,200,000
Proceeds from sales of securities available-for-sale			368,775,000	$ 86,018,000
Gross realized gains on sale of securities	313,000	$ 1,700,000	7,100,000	1,900,000
Gross realized losses on sale of securities	(60,000)	(76,000)	(575,000)	(379,000)
Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sales of securities available-for-sale	$ 62,300,000	$ 41,400,000	362,200,000	$ 84,500,000
Equity Securities
Schedule of Available-for-sale Securities [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			$ 7,100,000