Securities (Securities by Contractual Maturity) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available for Sale and Held to Maturty Securities [Line Items]
Available for sale debt securities maturities within 1 year amortized cost	$ 59,796
Available for sale debt securities maturities 1-5 years amortized cost	226,076
Available for sale debt securities maturities 5-10 years amortized cost	246,549
Available for sale debt securities maturities after 10 years amortized cost	187,493
Available for sale debt securities maturities total amortized cost	719,914
Available for sale debt securities maturities within 1 year fair value	59,636
Available for sale debt securities maturities 1-5 years fair value	224,715
Available for sale debt securities maturities 5-10 years fair value	243,740
Available for sale debt securities maturities after 10 years fair value	186,264
Available for sale debt securities fair value	714,355
Held to maturity debt securities maturities within 1 year amortized cost	1,792
Held to maturity debt securities maturities 1-5 years amortized cost	5,603
Held to maturity debt securities maturities 5-10 years amortized cost	4,239
Held to maturity debt securities maturities after 10 years amortized cost	1,607
Held to maturity securities	13,241	$ 15,633
Held to maturity debt securities maturities within 1 year fair value	1,832
Held to maturity debt securities maturities 1-5 years fair value	5,728
Held to maturity debt securities maturities 5-10 years fair value	4,334
Held to maturity debt securities maturities after 10 years fair value	1,643
Held to maturity securities fair value	$ 13,537	$ 15,920