Securities (Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Schedule of Available for Sale and Held to Maturty Securities [Line Items]
Available for sale debt securities maturities within 1 year amortized cost	$ 63,389
Available for sale debt securities maturities 1-5 years amortized cost	270,844
Available for sale debt securities maturities 5-10 years amortized cost	282,932
Available for sale debt securities maturities after 10 years amortized cost	187,056
Available for sale debt securities maturities total amortized cost	804,221
Available for sale debt securities maturities within 1 year fair value	61,419
Available for sale debt securities maturities 1-5 years fair value	261,678
Available for sale debt securities maturities 5-10 years fair value	272,643
Available for sale debt securities maturities after 10 years fair value	180,953
Available for sale debt securities fair value	776,693
Held to maturity debt securities maturities within 1 year amortized cost	1,419
Held to maturity debt securities maturities 1-5 years amortized cost	4,694
Held to maturity debt securities maturities 5-10 years amortized cost	3,882
Held to maturity debt securities maturities after 10 years amortized cost	1,417
Held to maturity securities	11,412	$ 12,541
Held to maturity debt securities maturities within 1 year fair value	1,413
Held to maturity debt securities maturities 1-5 years fair value	4,674
Held to maturity debt securities maturities 5-10 years fair value	3,866
Held to maturity debt securities maturities after 10 years fair value	1,411
Held to maturity securities fair value	$ 11,364	$ 12,721