Securities (Reconciliation of fair value of securities) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	$ 454,863	$ 448,219
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1,364	3,740
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(10,477)	(4,461)
Available-for-sale Securities	445,750	447,498
Held to maturity Securities, Amortized Cost	528,861	497,688
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	732	2,429
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(12,038)	(5,923)
Held to Maturity, Fair Value, Total	517,555	494,194
Amortized Cost	983,724	945,907
Gross Unrealized Gains	2,096	6,169
Unrealized Losses Other	(22,515)	(10,384)
Fair Value	963,305	941,692
U. S. Government Agency Securities [Member]
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	35,478	35,475
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		86
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(535)	(131)
Available-for-sale Securities	34,943	35,430
U.S. Treasury securities
Reconciliation of fair value of securities
Held to maturity Securities, Amortized Cost	1,005	1,006
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	16	29
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0	0
Held to Maturity, Fair Value, Total	1,021	1,035
Agency mortgage-backed securities
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	226,111	214,934
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1,266	1,897
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(4,166)	(1,067)
Available-for-sale Securities	223,211	215,764
Held to maturity Securities, Amortized Cost	192,961	204,768
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	474	1,791
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(3,026)	(736)
Held to Maturity, Fair Value, Total	190,409	205,823
Agency Collateralized Mortgage Obligations [Member]
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	139,433	124,098
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	73	78
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(4,314)	(2,164)
Available-for-sale Securities	135,192	122,012
Held to maturity Securities, Amortized Cost	306,395	262,998
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	126	397
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(8,703)	(4,987)
Held to Maturity, Fair Value, Total	297,818	258,408
State, County, and Municipal Securities [Member]
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	2,232	2,237
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	22	37
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Available-for-sale Securities	2,254	2,274
Single Issuer Trust Preferred Securities Issued by Banks and Insurers [Member]
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	2,002	2,012
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	3	4
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Available-for-sale Securities	2,005	2,016
Held to maturity Securities, Amortized Cost	1,500	1,500
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	21	29
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0	0
Held to Maturity, Fair Value, Total	1,521	1,529
Pooled trust preferred securities issued by banks and insurers
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	2,173	2,179
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0	0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(518)	(539)
Available-for-sale Securities	1,655	1,640
Small Business Administration Pooled Securities [Member]
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	47,434	47,852
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0	44
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	(944)	(118)
Available-for-sale Securities	46,490	47,778
Held to maturity Securities, Amortized Cost	27,000	27,416
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	95	183
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(309)	(200)
Held to Maturity, Fair Value, Total	26,786	27,399
Equity securities
Reconciliation of fair value of securities
Available for sale Securities, Amortized Cost	0	19,432
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax		1,594
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	$ 0	(442)
Available-for-sale Securities		$ 20,584

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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