Investment Securities (Maturities) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Held-to-Maturity Securities:
Held-to-maturity securities, Amortized Cost, Within one year	$ 3,241
Held-to-maturity securities, Fair Value, Within one year	3,243
Held-to-maturity securities, Amortized Cost, After 1 through 5 years	1,568
Held-to-maturity securities, Fair Value, After 1 through 5 years	1,601
Held-to-maturity securities, Amortized Cost, Mortgage-backed securities	315
Held-to-maturity securities, Fair Value, Mortgage-backed securities	328
Held-to-maturity securities, Amortized Cost	5,124	$ 5,504
Held-to-maturity securities, Fair Value	5,172	5,552
Available-for-Sale Securities:
Available-for-sale securities, Amortized Cost, Within one year	38,917
Available-for-sale securities, Fair Value, Within one year	39,170
Available-for-sale securities, Amortized Cost, After 1 through 5 years	41,470
Available-for-sale securities, Fair Value, After 1 through 5 years	41,908
Available-for-sale securities, Amortized Cost, After 5 through 10 years	290,124
Available-for-sale securities, Fair Value, After 5 through 10 years	291,350
Available-for-sale securities, Amortized Cost, After 10 years	156,694
Available-for-sale securities, Fair Value, After 10 years	157,647
Available-for-sale securities, Amortized Cost, Mortgage-backed securities	218,528
Available-for-sale securities, Fair Value, Mortgage-backed securities	219,846
Available-for-sale securities, Amortized Cost	745,733
Available-for-sale securities, Fair Value	$ 749,921	$ 758,015