Investment Securities - Gross Unrealized Losses of Aggregated by Investment Category and Length of Time that Individual Securities have been in Continuous Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Temporarily Impaired Securities, Available for sale securities, Fair Value, Less than 12 months	$ 6,844	$ 902
Temporarily Impaired Securities, Available for sale securities, Unrealized Losses, Less than 12 months	(41)	(98)
Temporarily Impaired Securities, Available for sale securities, Fair Value, 12 months or longer	116,058	164,808
Temporarily Impaired Securities, Available for sale securities, Unrealized Losses, 12 months or longer	(1,030)	(4,147)
Temporarily Impaired Securities, Available for sale securities, Fair Value	122,902	165,710
Temporarily Impaired Securities, Available for sale securities, Unrealized Losses	(1,071)	(4,245)
Temporarily Impaired Securities, Held to maturity securities, Fair Value, Less than 12 months		51,063
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses, Less than 12 months		(410)
Temporarily Impaired Securities, Held to maturity securities, Fair Value, 12 months or longer	62,388	128,876
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses, 12 months or longer	(155)	(2,580)
Temporarily Impaired Securities, Held to maturity securities, Fair Value	62,388	179,939
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses	(155)	(2,990)
Temporarily Impaired Securities, Fair Value, Less than 12 months	6,844	51,965
Temporarily Impaired Securities, Unrealized Losses, Less than 12 months	(41)	(508)
Temporarily Impaired Securities, Fair Value, 12 months or longer	178,446	293,684
Temporarily Impaired Securities, Unrealized Losses, 12 months or longer	(1,185)	(6,727)
Temporarily Impaired Securities, Fair Value	185,290	345,649
Temporarily Impaired Securities, Unrealized Losses	(1,226)	(7,235)
U.S. GSE Obligations
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Temporarily Impaired Securities, Available for sale securities, Fair Value, 12 months or longer	44,814	74,039
Temporarily Impaired Securities, Available for sale securities, Unrealized Losses, 12 months or longer	(186)	(965)
Temporarily Impaired Securities, Available for sale securities, Fair Value	44,814	74,039
Temporarily Impaired Securities, Available for sale securities, Unrealized Losses	(186)	(965)
Temporarily Impaired Securities, Held to maturity securities, Fair Value, Less than 12 months		4,995
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses, Less than 12 months		(5)
Temporarily Impaired Securities, Held to maturity securities, Fair Value, 12 months or longer	14,980	27,338
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses, 12 months or longer	(17)	(233)
Temporarily Impaired Securities, Held to maturity securities, Fair Value	14,980	32,333
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses	(17)	(238)
Mortgage Backed Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Temporarily Impaired Securities, Available for sale securities, Fair Value, Less than 12 months	6,844
Temporarily Impaired Securities, Available for sale securities, Unrealized Losses, Less than 12 months	(41)
Temporarily Impaired Securities, Available for sale securities, Fair Value, 12 months or longer	71,244	86,815
Temporarily Impaired Securities, Available for sale securities, Unrealized Losses, 12 months or longer	(844)	(3,121)
Temporarily Impaired Securities, Available for sale securities, Fair Value	78,088	86,815
Temporarily Impaired Securities, Available for sale securities, Unrealized Losses	(885)	(3,121)
Temporarily Impaired Securities, Held to maturity securities, Fair Value, Less than 12 months		30,719
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses, Less than 12 months		(216)
Temporarily Impaired Securities, Held to maturity securities, Fair Value, 12 months or longer	47,096	93,225
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses, 12 months or longer	(138)	(2,074)
Temporarily Impaired Securities, Held to maturity securities, Fair Value	47,096	123,944
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses	(138)	(2,290)
Corporate Debt Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Temporarily Impaired Securities, Available for sale securities, Fair Value, Less than 12 months		902
Temporarily Impaired Securities, Available for sale securities, Unrealized Losses, Less than 12 months		(98)
Temporarily Impaired Securities, Available for sale securities, Fair Value, 12 months or longer		3,954
Temporarily Impaired Securities, Available for sale securities, Unrealized Losses, 12 months or longer		(61)
Temporarily Impaired Securities, Available for sale securities, Fair Value		4,856
Temporarily Impaired Securities, Available for sale securities, Unrealized Losses		(159)
Temporarily Impaired Securities, Held to maturity securities, Fair Value, Less than 12 months		6,865
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses, Less than 12 months		(107)
Temporarily Impaired Securities, Held to maturity securities, Fair Value		6,865
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses		(107)
Municipal Securities
Schedule of Available for Sale Securities and Held to Maturity Securities [Line Items]
Temporarily Impaired Securities, Held to maturity securities, Fair Value, Less than 12 months		8,484
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses, Less than 12 months		(82)
Temporarily Impaired Securities, Held to maturity securities, Fair Value, 12 months or longer	312	8,313
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses, 12 months or longer		(273)
Temporarily Impaired Securities, Held to maturity securities, Fair Value	$ 312	16,797
Temporarily Impaired Securities, Held to maturity securities, Unrealized Losses		$ (355)