Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	$ 812,002	$ 811,369
Unrealized Gains	(11,411)	(13,097)
Unrealized Losses	(17,855)	(9,535)
Securities available-for-sale	805,558	814,931
US Government Agencies Debt Securities [Member]
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	13,797	13,989
Unrealized Gains	(13)	(24)
Unrealized Losses	(408)	(318)
Securities available-for-sale	13,402	13,695
Mortgage Backed Securities - Residential
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	204,967	215,079
Unrealized Gains	(1,335)	(2,071)
Unrealized Losses	(4,695)	(1,812)
Securities available-for-sale	201,607	215,338
Mortgage Backed Securities - Commercial
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	0	1
Unrealized Gains	0	0
Unrealized Losses	0	0
Securities available-for-sale	0	1
Collateralized Mortgage Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	357,971	346,005
Unrealized Gains	(81)	(370)
Unrealized Losses	(10,922)	(6,705)
Securities available-for-sale	347,130	339,670
State and Municipal Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	226,771	227,651
Unrealized Gains	(2,948)	(4,671)
Unrealized Losses	(1,830)	(700)
Securities available-for-sale	227,889	231,622
Collateralized Debt Obligations
Amortized cost and fair value of investments classified as available for sale
Amortized Cost	8,496	8,644
Unrealized Gains	(7,034)	(5,961)
Unrealized Losses	0	0
Securities available-for-sale	$ 15,530	$ 14,605

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
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-Publisher FASB
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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
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