Securities (Reconciliation of fair value of securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	$ 969	$ 3,740
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(15,603)	(4,461)
Debt Securities, Available-for-sale	435,861	447,498
Debt Securities, Available-for-sale, Amortized Cost	450,495	448,219
Held to maturity Securities, Amortized Cost	553,705	497,688
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	166	2,429
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(19,249)	(5,923)
Held to Maturity, Fair Value, Total	534,622	494,194
Amortized Cost	1,004,200	945,907
Gross Unrealized Gains	1,135	6,169
Unrealized Losses Other	(34,852)	(10,384)
Debt Securities, Available-for-sale and Held-to-maturity	970,483	941,692
U.S. Government agency securities
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax		86
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(907)	(131)
Debt Securities, Available-for-sale	31,572	35,430
Debt Securities, Available-for-sale, Amortized Cost	32,479	35,475
U.S. Treasury securities
Reconciliation of fair value of securities
Held to maturity Securities, Amortized Cost	1,004	1,006
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	2	29
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Held to Maturity, Fair Value, Total	1,006	1,035
Agency mortgage-backed securities
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	874	1,897
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(6,510)	(1,067)
Debt Securities, Available-for-sale	207,523	215,764
Debt Securities, Available-for-sale, Amortized Cost	213,159	214,934
Held to maturity Securities, Amortized Cost	189,479	204,768
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	136	1,791
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(5,527)	(736)
Held to Maturity, Fair Value, Total	184,088	205,823
Agency Collateralized Mortgage Obligations [Member]
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	83	78
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(6,202)	(2,164)
Debt Securities, Available-for-sale	137,645	122,012
Debt Securities, Available-for-sale, Amortized Cost	143,764	124,098
Held to maturity Securities, Amortized Cost	336,346	262,998
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	28	397
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(12,858)	(4,987)
Held to Maturity, Fair Value, Total	323,516	258,408
US States and Political Subdivisions Debt Securities [Member]
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	8	37
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-sale	1,981	2,274
Debt Securities, Available-for-sale, Amortized Cost	1,973	2,237
Single Issuer Trust Preferred Securities Issued by Banks and Insurers [Member]
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	4	4
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-sale	1,004	2,016
Debt Securities, Available-for-sale, Amortized Cost	1,000	2,012
Held to maturity Securities, Amortized Cost	1,500	1,500
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	29
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(10)	0
Held to Maturity, Fair Value, Total	1,490	1,529
Pooled trust preferred securities issued by banks and insurers
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(359)	(539)
Debt Securities, Available-for-sale	1,800	1,640
Debt Securities, Available-for-sale, Amortized Cost	2,159	2,179
Small Business Administration Pooled Securities [Member]
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	44
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(1,625)	(118)
Debt Securities, Available-for-sale	54,336	47,778
Debt Securities, Available-for-sale, Amortized Cost	55,961	47,852
Held to maturity Securities, Amortized Cost	25,376	27,416
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	183
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(854)	(200)
Held to Maturity, Fair Value, Total	24,522	27,399
Equity Securities [Member]
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax		1,594
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	(442)
Debt Securities, Available-for-sale		20,584
Debt Securities, Available-for-sale, Amortized Cost	$ 0	$ 19,432