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Investment Securities - Amortized Cost and Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	$ 142,213	$ 157,206
Held to maturity, Fair Value	145,118	153,894
Held-to-maturity, Gross Unrealized Gains	3,130	210
Held-to-maturity, Gross Unrealized Losses	(225)	(3,522)
Total	348,369	465,910
Available-for-sale, at fair value	358,724	462,464
Available-for-sale, Gross Unrealized Gains	10,557	1,748
Available-for-sale, Gross Unrealized Losses	(202)	(5,194)
Total investment securities, Amortized Cost	490,582	623,116
Total investment securities, Fair Value	503,842	616,358
Total investment securities, Gross Unrealized Gains	13,687	1,958
Total investment securities, Gross Unrealized Losses	(427)	(8,716)
MBS pass-through securities issued by FHLMC and FNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	80,166	88,606
Held to maturity, Fair Value	81,308	85,804
Held-to-maturity, Gross Unrealized Gains	1,357	7
Held-to-maturity, Gross Unrealized Losses	(215)	(2,809)
Total	62,654	95,339
Available-for-sale, at fair value	64,290	94,467
Available-for-sale, Gross Unrealized Gains	1,683	358
Available-for-sale, Gross Unrealized Losses	(47)	(1,230)
SBA-backed securities
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	8,001	8,720
Held to maturity, Fair Value	8,360	8,757
Held-to-maturity, Gross Unrealized Gains	359	37
Held-to-maturity, Gross Unrealized Losses	0	0
Total	36,014	50,722
Available-for-sale, at fair value	36,943	50,781
Available-for-sale, Gross Unrealized Gains	990	465
Available-for-sale, Gross Unrealized Losses	(61)	(406)
CMOs issued by FNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	10,679	11,447
Held to maturity, Fair Value	10,981	11,327
Held-to-maturity, Gross Unrealized Gains	302	0
Held-to-maturity, Gross Unrealized Losses	0	(120)
Total	24,168	28,275
Available-for-sale, at fair value	24,560	28,079
Available-for-sale, Gross Unrealized Gains	392	134
Available-for-sale, Gross Unrealized Losses	0	(330)
CMOs issued by FHLMC
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	32,568	33,583
Held to maturity, Fair Value	33,524	33,021
Held-to-maturity, Gross Unrealized Gains	966	8
Held-to-maturity, Gross Unrealized Losses	(10)	(570)
Total	138,731	145,979
Available-for-sale, at fair value	144,067	144,836
Available-for-sale, Gross Unrealized Gains	5,374	454
Available-for-sale, Gross Unrealized Losses	(38)	(1,597)
CMOs issued by GNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	3,757	3,739
Held to maturity, Fair Value	3,810	3,769
Held-to-maturity, Gross Unrealized Gains	53	30
Held-to-maturity, Gross Unrealized Losses	0	0
Total	12,621	11,294
Available-for-sale, at fair value	12,686	11,021
Available-for-sale, Gross Unrealized Gains	66	1
Available-for-sale, Gross Unrealized Losses	(1)	(274)
Debentures of government- sponsored agencies
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Total	23,069	52,956
Available-for-sale, at fair value	23,822	53,018
Available-for-sale, Gross Unrealized Gains	753	185
Available-for-sale, Gross Unrealized Losses	0	(123)
Privately issued CMOs
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Total	120	295
Available-for-sale, at fair value	119	297
Available-for-sale, Gross Unrealized Gains	0	2
Available-for-sale, Gross Unrealized Losses	(1)	0
Obligations of state and political subdivisions
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, Amortized Cost	7,042	11,111
Held to maturity, Fair Value	7,135	11,216
Held-to-maturity, Gross Unrealized Gains	93	128
Held-to-maturity, Gross Unrealized Losses	0	(23)
Total	48,993	79,046
Available-for-sale, at fair value	50,232	77,960
Available-for-sale, Gross Unrealized Gains	1,292	134
Available-for-sale, Gross Unrealized Losses	(53)	(1,220)
Corporate bonds
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Total	1,999	2,004
Available-for-sale, at fair value	2,005	2,005
Available-for-sale, Gross Unrealized Gains	7	15
Available-for-sale, Gross Unrealized Losses	$ (1)	$ (14)

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