Securities (Reconciliation of fair value of securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	$ 8,757	$ 1,233
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(392)	(9,029)
Debt Securities, Available-for-sale	391,975	442,752
Debt Securities, Available-for-sale, Amortized Cost	383,610	450,548
Held to maturity Securities, Amortized Cost	777,270	611,490
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	15,629	2,533
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(736)	(10,383)
Held to Maturity, Fair Value, Total	792,163	603,640
Amortized Cost	1,160,880	1,062,038
Gross Unrealized Gains	24,386	3,766
Unrealized Losses Other	(1,128)	(19,412)
Debt Securities, Available-for-sale and Held-to-maturity	1,184,138	1,046,392
U.S. Government agency securities
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	827
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	(439)
Debt Securities, Available-for-sale	33,302	32,038
Debt Securities, Available-for-sale, Amortized Cost	32,475	32,477
Held to maturity Securities, Amortized Cost	12,853	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	146
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Held to Maturity, Fair Value, Total	12,999
U.S. Treasury securities
Reconciliation of fair value of securities
Held to maturity Securities, Amortized Cost	1,003	1,004
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	19	11
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	0
Held to Maturity, Fair Value, Total	1,022	1,015
Agency mortgage-backed securities
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	4,330	1,020
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	(5)	(3,406)
Debt Securities, Available-for-sale	200,603	220,105
Debt Securities, Available-for-sale, Amortized Cost	196,278	222,491
Held to maturity Securities, Amortized Cost	418,350	252,484
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	8,900	1,548
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(39)	(3,104)
Held to Maturity, Fair Value, Total	427,211	250,928
Agency Collateralized Mortgage Obligations [Member]
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,964	197
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	(3,435)
Debt Securities, Available-for-sale	94,538	134,911
Debt Securities, Available-for-sale, Amortized Cost	92,574	138,149
Held to maturity Securities, Amortized Cost	310,352	332,775
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	5,857	869
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(687)	(6,920)
Held to Maturity, Fair Value, Total	315,522	326,724
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	23	16
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	0
Debt Securities, Available-for-sale	1,736	1,735
Debt Securities, Available-for-sale, Amortized Cost	1,713	1,719
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	3
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	(10)
Debt Securities, Available-for-sale	720	707
Debt Securities, Available-for-sale, Amortized Cost	717	717
Held to maturity Securities, Amortized Cost	1,500	1,500
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	0	0
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	(10)	(10)
Held to Maturity, Fair Value, Total	1,490	1,490
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	(387)	(349)
Debt Securities, Available-for-sale	1,106	1,329
Debt Securities, Available-for-sale, Amortized Cost	1,493	1,678
Small Business Administration Pooled Securities [Member]
Reconciliation of fair value of securities
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,610	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	0	(1,390)
Debt Securities, Available-for-sale	59,970	51,927
Debt Securities, Available-for-sale, Amortized Cost	58,360	53,317
Held to maturity Securities, Amortized Cost	33,212	23,727
Debt Securities, Held-to-maturity, Accumulated Unrecognized Gain	707	105
Debt Securities, Held-to-maturity, Accumulated Unrecognized Loss	0	(349)
Held to Maturity, Fair Value, Total	$ 33,919	$ 23,483

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