Investment Securities (Textual) (Details) $ in Thousands	Dec. 31, 2018 USD ($) security	Jan. 01, 2018 USD ($)	Dec. 31, 2017 USD ($)
Investments, Debt and Equity Securities [Abstract]
Number of securities in portfolio (in security) | security	2,096
Number of securities in an unrealized loss position in portfolio (in security) | security	1,408
Fair Value			$ 1,824
Debt and Equity Securities, FV-NI [Line Items]
Retained earnings	$ 616,149		419,403
Collateral pledged
Debt and Equity Securities, FV-NI [Line Items]
Securities pledged as collateral	$ 1,050,000		937,200
Accounting Standards Update 2016-01
Debt and Equity Securities, FV-NI [Line Items]
Retained earnings		$ (344)	$ (300)