Securities (Schedule of Contractual Maturities of Securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Available for Sale, Fair Value
Debt Securities, Available-for-sale, Amortized Cost	$ 419,452	$ 420,703
Debt Securities, Available-for-sale	437,296	426,424
Held to Maturity, Fair Value
Debt Securities, Held-to-maturity	777,798	740,806
Held to Maturity, Fair Value, Total	809,355	753,263
Available for Sale Securities and Held to Maturity Securities Amortized Cost	1,197,250
Debt Securities, Available-for-sale and Held-to-maturity	1,246,651
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Amortized Cost	8,869
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, within One Year, Fair Value	8,965
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Amortized Cost	88,712
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, after One Through Five Years, Fair Value	92,400
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Amortized Cost	104,169
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Five Through Ten Years, Fair Value	110,586
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Ten Years, Amortized Cost	995,500
Debt Securities, Available-for-sale and Held-to-maturity, Maturity, Allocated and Single Maturity Date, after Ten Years, Fair Value	1,034,700
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	0
Available for Sale, Amortized Cost, Due after one year to five years	10,002
Available for Sale, Amortized Cost, Due after five to ten years	12,472
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	10,351
Available for Sale, Fair Value, Due after five to ten years	13,941
Available for Sale, Fair Value, Due after ten years	0
Debt Securities, Available-for-sale, Amortized Cost	22,474	32,473
Debt Securities, Available-for-sale	24,292	33,115
Held to Maturity, Fair Value
Debt Securities, Held-to-maturity	0	12,874
Held to Maturity, Fair Value, Total	0	12,997
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	63,062
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	64,421
Debt Securities, Available-for-sale, Amortized Cost	63,062	54,024
Debt Securities, Available-for-sale	64,421	54,795
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	30,716
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	31,461
Debt Securities, Held-to-maturity	30,716	31,324
Held to Maturity, Fair Value, Total	31,461	31,607
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	250
Available for Sale, Amortized Cost, Due after one year to five years	82,781
Available for Sale, Amortized Cost, Due after five to ten years	54,546
Available for Sale, Amortized Cost, Due after ten years	281,875
Available for Sale, Fair Value
Available for Sale, Fair Value, Due in one year or less	250
Available for Sale, Fair Value, Due after one year to five years	86,310
Available for Sale, Fair Value, Due after five to ten years	58,751
Available for Sale, Fair Value, Due after ten years	291,985
Held to Maturity, Amortized Cost
Held to Maturity, Amortized Cost, Due in one year or less	8,619
Held to Maturity, Amortized Cost, Due after one year to five years	5,931
Held to Maturity, Amortized Cost, Due after five to ten years	49,623
Held to Maturity, Amortized Cost, Due after ten years	713,625
Held to Maturity, Fair Value
Held to Maturity, Fair Value, Due in one year or less	8,715
Held to Maturity, Fair Value, Due after one year to five years	6,090
Held to Maturity, Fair Value, Due after five to ten years	51,835
Held to Maturity, Fair Value, Due after ten years	742,715
Held to Maturity, Fair Value, Total	809,355
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	1,443
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	1,009
Debt Securities, Available-for-sale, Amortized Cost	1,443	1,488
Debt Securities, Available-for-sale	1,009	1,114
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	489
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	436
Debt Securities, Available-for-sale, Amortized Cost	489	488
Debt Securities, Available-for-sale	436	493
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, 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
Debt Securities, Held-to-maturity	1,500	1,500
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	250
Available for Sale, Amortized Cost, Due after one year to five years	687
Available for Sale, Amortized Cost, Due after five to ten years	189
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	250
Available for Sale, Fair Value, Due after one year to five years	691
Available for Sale, Fair Value, Due after five to ten years	203
Available for Sale, Fair Value, Due after ten years	0
Debt Securities, Available-for-sale, Amortized Cost	1,126	1,377
Debt Securities, Available-for-sale	1,144	1,396
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	83,183
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	87,210
Debt Securities, Available-for-sale, Amortized Cost	83,183	87,305
Debt Securities, Available-for-sale	87,210	88,511
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	277,921
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	289,902
Debt Securities, Held-to-maturity	277,921	293,662
Held to Maturity, Fair Value, Total	289,902	297,314
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	0
Available for Sale, Amortized Cost, Due after one year to five years	72,092
Available for Sale, Amortized Cost, Due after five to ten years	41,885
Available for Sale, Amortized Cost, Due after ten years	133,698
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	75,268
Available for Sale, Fair Value, Due after five to ten years	44,607
Available for Sale, Fair Value, Due after ten years	138,909
Debt Securities, Available-for-sale, Amortized Cost	247,675	243,548
Debt Securities, Available-for-sale	258,784	247,000
Held to Maturity, Amortized Cost
Held to Maturity, Amortized Cost, Due in one year or less	8,619
Held to Maturity, Amortized Cost, Due after one year to five years	1,902
Held to Maturity, Amortized Cost, Due after five to ten years	48,123
Held to Maturity, Amortized Cost, Due after ten years	404,988
Held to Maturity, Fair Value
Held to Maturity, Fair Value, Due in one year or less	8,715
Held to Maturity, Fair Value, Due after one year to five years	1,951
Held to Maturity, Fair Value, Due after five to ten years	50,345
Held to Maturity, Fair Value, Due after ten years	421,352
Debt Securities, Held-to-maturity	463,632	397,414
Held to Maturity, Fair Value, Total	482,363	405,802
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	4,029
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, 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	4,139
Held to Maturity, Fair Value, Due after five to ten years	0
Held to Maturity, Fair Value, Due after ten years	0
Debt Securities, Held-to-maturity	4,029	4,032
Held to Maturity, Fair Value, Total	$ 4,139	$ 4,053