Investment Securities - Summary of Carrying Amounts of Securities and Their Approximate Fair Values (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Amortized Cost	$ 153,765	$ 172,290
Available for sale securities, Gross Unrealized Gains	359	118
Available for sale securities, Gross Unrealized Losses	(1,071)	(4,245)
Available for sale securities, Fair Value	153,053	168,163
Held to maturity securities, Amortized Cost	286,350	282,869
Held to maturity securities, Gross Unrealized Gains	5,798	1,431
Held to maturity securities, Gross Unrealized Losses	(155)	(2,990)
Held to maturity securities, Fair Value	291,993	281,310
Total, Amortized Cost	440,115	455,159
Total, Gross Unrealized Gains	6,157	1,549
Total, Gross Unrealized Losses	(1,226)	(7,235)
Total, Fair Value	445,046	449,473
U.S. GSE Obligations
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Amortized Cost	50,000	75,004
Available for sale securities, Gross Unrealized Gains	1
Available for sale securities, Gross Unrealized Losses	(186)	(965)
Available for sale securities, Fair Value	49,815	74,039
Held to maturity securities, Amortized Cost	22,572	32,571
Held to maturity securities, Gross Unrealized Gains	3
Held to maturity securities, Gross Unrealized Losses	(17)	(238)
Held to maturity securities, Fair Value	22,558	32,333
Corporate Debt Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Amortized Cost		5,015
Available for sale securities, Gross Unrealized Losses		(159)
Available for sale securities, Fair Value		4,856
Held to maturity securities, Amortized Cost	6,977	6,972
Held to maturity securities, Gross Unrealized Gains	92
Held to maturity securities, Gross Unrealized Losses		(107)
Held to maturity securities, Fair Value	7,069	6,865
Mortgage Backed Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Available for sale securities, Amortized Cost	103,765	92,271
Available for sale securities, Gross Unrealized Gains	358	118
Available for sale securities, Gross Unrealized Losses	(885)	(3,121)
Available for sale securities, Fair Value	103,238	89,268
Held to maturity securities, Amortized Cost	181,776	168,118
Held to maturity securities, Gross Unrealized Gains	2,790	134
Held to maturity securities, Gross Unrealized Losses	(138)	(2,290)
Held to maturity securities, Fair Value	184,428	165,962
Municipal Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Held to maturity securities, Amortized Cost	75,025	75,208
Held to maturity securities, Gross Unrealized Gains	2,913	1,297
Held to maturity securities, Gross Unrealized Losses		(355)
Held to maturity securities, Fair Value	$ 77,938	$ 76,150

Investments securities accumulated unrealized gains.

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Investments securities amortized cost.

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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