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Investment Securities - Amortized Cost and Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, amortized cost	$ 117,350	$ 137,413
Held to maturity, fair value	123,983	139,642
Held-to-maturity, gross unrealized gains	6,633	2,378
Held-to-maturity, gross unrealized losses	0	(149)
Total	394,437	423,923
Available-for-sale, at fair value	413,464	432,260
Available-for-sale, gross unrealized gains	19,085	8,748
Available-for-sale, gross unrealized losses	(58)	(411)
Total investment securities, amortized cost	511,787	561,336
Total investment securities, fair value	537,447	571,902
Total investment securities, gross unrealized gains	25,718	11,126
Total investment securities, gross unrealized losses	(58)	(560)
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	69,797	80,451
Held to maturity, fair value	73,884	81,325
Held-to-maturity, gross unrealized gains	4,087	1,018
Held-to-maturity, gross unrealized losses	0	(144)
Total	56,679	98,502
Available-for-sale, at fair value	59,482	100,071
Available-for-sale, gross unrealized gains	2,803	1,617
Available-for-sale, gross unrealized losses	0	(48)
SBA-backed securities
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, amortized cost	6,549	7,999
Held to maturity, fair value	6,979	8,264
Held-to-maturity, gross unrealized gains	430	265
Held-to-maturity, gross unrealized losses	0	0
Total	31,057	35,674
Available-for-sale, at fair value	32,844	36,286
Available-for-sale, gross unrealized gains	1,844	688
Available-for-sale, gross unrealized losses	(57)	(76)
CMOs issued by FNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, amortized cost	8,440	10,210
Held to maturity, fair value	8,834	10,492
Held-to-maturity, gross unrealized gains	394	282
Held-to-maturity, gross unrealized losses	0	0
Total	18,285	22,702
Available-for-sale, at fair value	18,961	23,092
Available-for-sale, gross unrealized gains	676	390
Available-for-sale, gross unrealized losses	0	0
CMOs issued by FHLMC
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, amortized cost	29,657	31,477
Held to maturity, fair value	31,331	32,157
Held-to-maturity, gross unrealized gains	1,674	685
Held-to-maturity, gross unrealized losses	0	(5)
Total	144,600	139,398
Available-for-sale, at fair value	153,255	143,226
Available-for-sale, gross unrealized gains	8,656	3,892
Available-for-sale, gross unrealized losses	(1)	(64)
CMOs issued by GNMA
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, amortized cost	1,230	3,763
Held to maturity, fair value	1,235	3,816
Held-to-maturity, gross unrealized gains	5	53
Held-to-maturity, gross unrealized losses	0	0
Total	9,064	11,719
Available-for-sale, at fair value	9,491	11,755
Available-for-sale, gross unrealized gains	427	42
Available-for-sale, gross unrealized losses	0	(6)
Debentures of government- sponsored agencies
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Total	45,239	48,389
Available-for-sale, at fair value	45,688	49,046
Available-for-sale, gross unrealized gains	449	727
Available-for-sale, gross unrealized losses	0	(70)
Obligations of state and political subdivisions
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Held to maturity, amortized cost	1,677	3,513
Held to maturity, fair value	1,720	3,588
Held-to-maturity, gross unrealized gains	43	75
Held-to-maturity, gross unrealized losses	0	0
Total	89,513	66,042
Available-for-sale, at fair value	93,743	67,282
Available-for-sale, gross unrealized gains	4,230	1,386
Available-for-sale, gross unrealized losses	0	(146)
Corporate bonds
Schedule of Available-for-sale Securities and Held-to-maturity Securities [Line Items]
Total	0	1,497
Available-for-sale, at fair value	0	1,502
Available-for-sale, gross unrealized gains	0	6
Available-for-sale, gross unrealized losses	$ 0	$ (1)

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