Securities (Schedule of Contractual Maturities of Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Available for Sale, Amortized Cost
Available for sale Securities, Amortized Cost	$ 454,863	$ 448,219
Available for Sale, Fair Value
Available for sale Securities, Fair Value, Total	445,750	447,498
Held to Maturity, Amortized Cost
Held to maturity Securities, Amortized Cost	528,861	497,688
Held to Maturity, Fair Value
Held to Maturity, Fair Value, Total	517,555	494,194
Debt Securities
Available for Sale, Amortized Cost
Available for Sale, Amortized Cost, Due in one year or less	3,089
Available for Sale, Amortized Cost, Due after one year to five years	64,058
Available for Sale, Amortized Cost, Due after five to ten years	111,300
Available for Sale, Amortized Cost, Due after ten years	276,416
Available for sale Securities, Amortized Cost	454,863
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	3,088
Available for Sale, Fair Value, Due after one year to five years	63,123
Available for Sale, Fair Value, Due after five to ten years	109,515
Available for Sale, Fair Value, Due after ten years	270,024
Available for sale Securities, Fair Value, Total	445,750
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	10,057
Held to Maturity, Amortized Cost, Due after five to ten years	15,483
Held to Maturity, Amortized Cost, Due after ten years	503,321
Held to maturity Securities, Amortized Cost	528,861
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	9,953
Held to Maturity, Fair Value, Due after five to ten years	15,569
Held to Maturity, Fair Value, Due after ten years	492,033
Held to Maturity, Fair Value, Total	517,555
U.S. Government agency securities
Available for Sale, Amortized Cost
Available for Sale, Amortized Cost, Due in one year or less	2,997
Available for Sale, Amortized Cost, Due after one year to five years	20,016
Available for Sale, Amortized Cost, Due after five to ten years	12,465
Available for Sale, Amortized Cost, Due after ten years	0
Available for sale Securities, Amortized Cost	35,478	35,475
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	2,995
Available for Sale, Fair Value, Due after one year to five years	19,860
Available for Sale, Fair Value, Due after five to ten years	12,088
Available for Sale, Fair Value, Due after ten years	0
Available for sale Securities, Fair Value, Total	34,943	35,430
Small Business Administration Pooled Securities [Member]
Available for Sale, Amortized Cost
Available for Sale, Amortized Cost, Due in one year or less	0
Available for Sale, Amortized Cost, Due after one year to five years	0
Available for Sale, Amortized Cost, Due after five to ten years	0
Available for Sale, Amortized Cost, Due after ten years	47,434
Available for sale Securities, Amortized Cost	47,434	47,852
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	0
Available for Sale, Fair Value, Due after one year to five years	0
Available for Sale, Fair Value, Due after five to ten years	0
Available for Sale, Fair Value, Due after ten years	46,490
Available for sale Securities, Fair Value, Total	46,490	47,778
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	0
Held to Maturity, Amortized Cost, Due after five to ten years	0
Held to Maturity, Amortized Cost, Due after ten years	27,000
Held to maturity Securities, Amortized Cost	27,000	27,416
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	0
Held to Maturity, Fair Value, Due after five to ten years	0
Held to Maturity, Fair Value, Due after ten years	26,786
Held to Maturity, Fair Value, Total	26,786	27,399
Pooled trust preferred securities issued by banks and insurers
Available for Sale, Amortized Cost
Available for Sale, Amortized Cost, Due in one year or less	0
Available for Sale, Amortized Cost, Due after one year to five years	0
Available for Sale, Amortized Cost, Due after five to ten years	0
Available for Sale, Amortized Cost, Due after ten years	2,173
Available for sale Securities, Amortized Cost	2,173	2,179
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	0
Available for Sale, Fair Value, Due after one year to five years	0
Available for Sale, Fair Value, Due after five to ten years	0
Available for Sale, Fair Value, Due after ten years	1,655
Available for sale Securities, Fair Value, Total	1,655	1,640
Single Issuer Trust Preferred Securities Issued by Banks and Insurers [Member]
Available for Sale, Amortized Cost
Available for Sale, Amortized Cost, Due in one year or less	0
Available for Sale, Amortized Cost, Due after one year to five years	0
Available for Sale, Amortized Cost, Due after five to ten years	0
Available for Sale, Amortized Cost, Due after ten years	2,002
Available for sale Securities, Amortized Cost	2,002	2,012
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	0
Available for Sale, Fair Value, Due after one year to five years	0
Available for Sale, Fair Value, Due after five to ten years	0
Available for Sale, Fair Value, Due after ten years	2,005
Available for sale Securities, Fair Value, Total	2,005	2,016
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	0
Held to Maturity, Amortized Cost, Due after five to ten years	0
Held to Maturity, Amortized Cost, Due after ten years	1,500
Held to maturity Securities, Amortized Cost	1,500	1,500
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	0
Held to Maturity, Fair Value, Due after five to ten years	0
Held to Maturity, Fair Value, Due after ten years	1,521
Held to Maturity, Fair Value, Total	1,521	1,529
US States and Political Subdivisions Debt Securities [Member]
Available for Sale, Amortized Cost
Available for Sale, Amortized Cost, Due in one year or less	0
Available for Sale, Amortized Cost, Due after one year to five years	1,026
Available for Sale, Amortized Cost, Due after five to ten years	1,206
Available for Sale, Amortized Cost, Due after ten years	0
Available for sale Securities, Amortized Cost	2,232	2,237
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	0
Available for Sale, Fair Value, Due after one year to five years	1,028
Available for Sale, Fair Value, Due after five to ten years	1,226
Available for Sale, Fair Value, Due after ten years	0
Available for sale Securities, Fair Value, Total	2,254	2,274
Collateralized Debt Obligations [Member]
Available for Sale, Amortized Cost
Available for Sale, Amortized Cost, Due in one year or less	8
Available for Sale, Amortized Cost, Due after one year to five years	0
Available for Sale, Amortized Cost, Due after five to ten years	0
Available for Sale, Amortized Cost, Due after ten years	139,425
Available for sale Securities, Amortized Cost	139,433	124,098
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	8
Available for Sale, Fair Value, Due after one year to five years	0
Available for Sale, Fair Value, Due after five to ten years	0
Available for Sale, Fair Value, Due after ten years	135,184
Available for sale Securities, Fair Value, Total	135,192	122,012
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	0
Held to Maturity, Amortized Cost, Due after five to ten years	1,426
Held to Maturity, Amortized Cost, Due after ten years	304,969
Held to maturity Securities, Amortized Cost	306,395	262,998
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	0
Held to Maturity, Fair Value, Due after five to ten years	1,423
Held to Maturity, Fair Value, Due after ten years	296,395
Held to Maturity, Fair Value, Total	297,818	258,408
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Available for Sale, Amortized Cost
Available for Sale, Amortized Cost, Due in one year or less	84
Available for Sale, Amortized Cost, Due after one year to five years	43,016
Available for Sale, Amortized Cost, Due after five to ten years	97,629
Available for Sale, Amortized Cost, Due after ten years	85,382
Available for sale Securities, Amortized Cost	226,111	214,934
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	85
Available for Sale, Fair Value, Due after one year to five years	42,235
Available for Sale, Fair Value, Due after five to ten years	96,201
Available for Sale, Fair Value, Due after ten years	84,690
Available for sale Securities, Fair Value, Total	223,211	215,764
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	9,052
Held to Maturity, Amortized Cost, Due after five to ten years	14,057
Held to Maturity, Amortized Cost, Due after ten years	169,852
Held to maturity Securities, Amortized Cost	192,961	204,768
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	8,932
Held to Maturity, Fair Value, Due after five to ten years	14,146
Held to Maturity, Fair Value, Due after ten years	167,331
Held to Maturity, Fair Value, Total	190,409	205,823
US Treasury Securities [Member]
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	1,005
Held to Maturity, Amortized Cost, Due after five to ten years	0
Held to Maturity, Amortized Cost, Due after ten years	0
Held to maturity Securities, Amortized Cost	1,005	1,006
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	1,021
Held to Maturity, Fair Value, Due after five to ten years	0
Held to Maturity, Fair Value, Due after ten years	0
Held to Maturity, Fair Value, Total	$ 1,021	$ 1,035