Securities (Summary of Book Values and Fair Values of Investment Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value
Amortized Cost	$ 697,897	$ 513,741
Fair Value	705,224	501,351
Unrealized Gains	8,901	178
Unrealized (Losses)	(1,574)	(12,568)
Debt Securities, Held-to-maturity, Maturity [Abstract]
Amortized Cost	74,265	101,237
Fair Value	74,465	99,906
Unrealized Gains	369	525
Unrealized (Losses)	(169)	(1,856)
Government-sponsored enterprise securities
Fair Value
Amortized Cost	30,000	82,995
Fair Value	30,053	82,662
Unrealized Gains	55	63
Unrealized (Losses)	(2)	(396)
Mortgage-backed securities
Fair Value
Amortized Cost	634,176	396,995
Fair Value	640,488	385,551
Unrealized Gains	7,794	39
Unrealized (Losses)	(1,482)	(11,483)
Debt Securities, Held-to-maturity, Maturity [Abstract]
Amortized Cost	43,968	52,048
Fair Value	43,801	50,241
Unrealized Gains	0	0
Unrealized (Losses)	(167)	(1,807)
Corporate bonds
Fair Value
Amortized Cost	33,721	33,751
Fair Value	34,683	33,138
Unrealized Gains	1,052	76
Unrealized (Losses)	(90)	(689)
State and local governments
Debt Securities, Held-to-maturity, Maturity [Abstract]
Amortized Cost	30,297	49,189
Fair Value	30,664	49,665
Unrealized Gains	369	525
Unrealized (Losses)	$ (2)	$ (49)

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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