Securities (Schedule of Contractual Maturities of Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Available for Sale, Fair Value
Debt Securities, Available-for-sale, Amortized Cost	$ 439,307	$ 450,548
Debt Securities, Available-for-sale	437,689	442,752
Held to Maturity, Amortized Cost
Held to maturity Securities, Amortized Cost	623,243	611,490
Held to Maturity, Fair Value
Held to Maturity, Fair Value, Total	623,156	603,640
Available for Sale Securities and Held to Maturity Securities Amortized Cost	1,062,550	1,062,038
Debt Securities, Available-for-sale and Held-to-maturity	1,060,845	1,046,392
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost	10,012
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value	9,972
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost	75,869
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value	75,666
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost	137,678
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value	137,965
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Ten Years, Amortized Cost	838,991
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Ten Years, Fair Value	837,242
U.S. Government agency securities
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available for Sale, Amortized Cost, Due in one year or less	10,005
Available for Sale, Amortized Cost, Due after one year to five years	10,003
Available for Sale, Amortized Cost, Due after five to ten years	12,469
Available for Sale, Amortized Cost, Due after ten years	0
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	9,965
Available for Sale, Fair Value, Due after one year to five years	10,028
Available for Sale, Fair Value, Due after five to ten years	12,462
Available for Sale, Fair Value, Due after ten years	0
Debt Securities, Available-for-sale, Amortized Cost	32,477	32,477
Debt Securities, Available-for-sale	32,455	32,038
Small Business Administration Pooled Securities [Member]
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
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	52,549
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	52,134
Debt Securities, Available-for-sale, Amortized Cost	52,549	53,317
Debt Securities, Available-for-sale	52,134	51,927
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	23,336
Held to maturity Securities, Amortized Cost	23,336	23,727
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	23,062
Held to Maturity, Fair Value, Total	23,062	23,483
Debt Securities [Member]
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available for Sale, Amortized Cost, Due in one year or less	10,012
Available for Sale, Amortized Cost, Due after one year to five years	63,079
Available for Sale, Amortized Cost, Due after five to ten years	101,498
Available for Sale, Amortized Cost, Due after ten years	264,718
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	9,972
Available for Sale, Fair Value, Due after one year to five years	62,925
Available for Sale, Fair Value, Due after five to ten years	101,880
Available for Sale, Fair Value, Due after ten years	262,912
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	12,790
Held to Maturity, Amortized Cost, Due after five to ten years	36,180
Held to Maturity, Amortized Cost, Due after ten years	574,273
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	12,741
Held to Maturity, Fair Value, Due after five to ten years	36,085
Held to Maturity, Fair Value, Due after ten years	574,330
Held to Maturity, Fair Value, Total	623,156
Pooled trust preferred securities issued by banks and insurers
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
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	1,660
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	1,314
Debt Securities, Available-for-sale, Amortized Cost	1,660	1,678
Debt Securities, Available-for-sale	1,314	1,329
Single Issuer Trust Preferred Securities Issued by Banks and Insurers [Member]
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
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	717
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	721
Debt Securities, Available-for-sale, Amortized Cost	717	717
Debt Securities, Available-for-sale	721	707
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	1,500
Held to Maturity, Amortized Cost, Due after ten years	0
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	1,490
Held to Maturity, Fair Value, Due after ten years	0
Held to Maturity, Fair Value, Total	1,490	1,490
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available for Sale, Amortized Cost, Due in one year or less	0
Available for Sale, Amortized Cost, Due after one year to five years	1,022
Available for Sale, Amortized Cost, Due after five to ten years	694
Available for Sale, Amortized Cost, Due after ten years	0
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	1,026
Available for Sale, Fair Value, Due after five to ten years	713
Available for Sale, Fair Value, Due after ten years	0
Debt Securities, Available-for-sale, Amortized Cost	1,716	1,719
Debt Securities, Available-for-sale	1,739	1,735
Agency Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
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	133,025
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	131,531
Debt Securities, Available-for-sale, Amortized Cost	133,025	138,149
Debt Securities, Available-for-sale	131,531	134,911
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	553
Held to Maturity, Amortized Cost, Due after ten years	337,251
Held to maturity Securities, Amortized Cost	337,804	332,775
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	551
Held to Maturity, Fair Value, Due after ten years	335,154
Held to Maturity, Fair Value, Total	335,705	326,724
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Available for Sale, Amortized Cost, Due in one year or less	7
Available for Sale, Amortized Cost, Due after one year to five years	52,054
Available for Sale, Amortized Cost, Due after five to ten years	88,335
Available for Sale, Amortized Cost, Due after ten years	76,767
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	7
Available for Sale, Fair Value, Due after one year to five years	51,871
Available for Sale, Fair Value, Due after five to ten years	88,705
Available for Sale, Fair Value, Due after ten years	77,212
Debt Securities, Available-for-sale, Amortized Cost	217,163	222,491
Debt Securities, Available-for-sale	217,795	220,105
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	11,786
Held to Maturity, Amortized Cost, Due after five to ten years	34,127
Held to Maturity, Amortized Cost, Due after ten years	213,686
Held to maturity Securities, Amortized Cost	259,599	252,484
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	11,724
Held to Maturity, Fair Value, Due after five to ten years	34,044
Held to Maturity, Fair Value, Due after ten years	216,114
Held to Maturity, Fair Value, Total	261,882	250,928
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	1,004
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	1,004	1,004
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	1,017
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	$ 1,017	$ 1,015