INVESTMENT SECURITIES - AFS (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2008
Securities available for sale:
Amortized Cost	$ 456,133	$ 479,825
Gross Unrealized Gains	4,101	4,310
Gross Unrealized Losses	(1,515)	(2,860)
Fair Value	458,719	481,275
U.S. Treasury securities and U.S. Government agencies
Securities available for sale:
Amortized Cost	236,899	295,425
Gross Unrealized Gains	13	226
Gross Unrealized Losses	(653)	(1,107)
Fair Value	236,259	294,544
Private label mortgage backed security
Securities available for sale:
Amortized Cost	3,245	3,691
Gross Unrealized Gains	1,330	1,086
Fair Value	4,575	4,777
Mortgage backed securities - residential
Securities available for sale:
Amortized Cost	102,657	71,197
Gross Unrealized Gains	1,644	2,027
Gross Unrealized Losses	(299)	(220)
Fair Value	104,002	73,004
Collateralized mortgage obligations
Securities available for sale:
Amortized Cost	92,348	88,559
Gross Unrealized Gains	425	334
Gross Unrealized Losses	(539)	(1,239)
Fair Value	92,234	87,654
Freddie Mac preferred stock
Securities available for sale:
Gross Unrealized Gains	407	483
Fair Value	407	483	$ 0
Community Reinvestment Act mutual fund
Securities available for sale:
Amortized Cost	2,500	2,500
Gross Unrealized Gains	5
Gross Unrealized Losses	(24)	(45)
Fair Value	2,481	2,455
Corporate bonds
Securities available for sale:
Amortized Cost	15,002	15,004
Gross Unrealized Gains	259	154
Fair Value	15,261	15,158
Trust preferred security
Securities available for sale:
Amortized Cost	3,482	3,449
Gross Unrealized Gains	18
Gross Unrealized Losses		(249)
Fair Value	$ 3,500	$ 3,200

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
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