Securities (Schedule of Contractual Maturities of Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Available for Sale, Amortized Cost
Available for sale Securities, Amortized Cost	$ 413,496	$ 363,366
Available for Sale, Fair Value
Available for sale Securities, Fair Value, Total	415,943	363,644
Held to Maturity, Amortized Cost
Held to maturity Securities, Amortized Cost	498,392	487,076
Held to Maturity, Fair Value
Held to Maturity, Fair Value, Total	499,059	$ 485,650
Debt Securities
Available for Sale, Amortized Cost
Available for Sale, Amortized Cost, Due in one year or less	3,660
Available for Sale, Amortized Cost, Due after one year to five years	35,607
Available for Sale, Amortized Cost, Due after five to ten years	96,985
Available for Sale, Amortized Cost, Due after ten years	258,083
Available for sale Securities, Amortized Cost	394,335
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	3,672
Available for Sale, Fair Value, Due after one year to five years	36,122
Available for Sale, Fair Value, Due after five to ten years	97,760
Available for Sale, Fair Value, Due after ten years	258,566
Available for sale Securities, Fair Value, Total	396,120
Held to Maturity, Amortized Cost
Held to Maturity, Amortized Cost, Due in one year or less	0
Held to Maturity, Amortized Cost, Due after one year to five years	15,824
Held to Maturity, Amortized Cost, Due after five to ten years	19,574
Held to Maturity, Amortized Cost, Due after ten years	462,994
Held to maturity Securities, Amortized Cost	498,392
Held to Maturity, Fair Value
Held to Maturity, Fair Value, Due in one year or less	0
Held to Maturity, Fair Value, Due after one year to five years	16,064
Held to Maturity, Fair Value, Due after five to ten years	20,045
Held to Maturity, Fair Value, Due after ten years	462,950
Held to Maturity, Fair Value, Total	499,059
Equity securities
Available for Sale, Amortized Cost
Available for Sale, Amortized Cost, Marketable equity securities	19,161
Available for Sale, Fair Value
Available for Sale, Fair Value, Marketable equity securities	19,823
Held to Maturity, Amortized Cost
Held to maturity Securities, Amortized Cost	0
Held to Maturity, Fair Value
Held to Maturity, Fair Value, Total	$ 0