Accumulated Other Comprehensive (Loss) Income - Components of Accumulated Other Comprehensive (Loss) Income, Net of Taxes (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance				$ (28,416)	$ (17,771)
Net Change		$ 2,289	$ (1,216)	6,384	(5,882)
Ending balance		(21,949)	(28,007)	(21,949)	(28,007)
Accounting Standards Update 2017-12
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption						$ 0
Accounting Standards Update 2016-01
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption							$ 0
Accounting Standards Update 2018-02
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption							0
Net Unrealized Holding (Losses) Gains on Available-for-Sale Investment Securities [Member]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance				(11,221)	(4,061)
Net Change				6,356	(6,525)
Ending balance		(4,865)	(11,987)	(4,865)	(11,987)
Net Unrealized Holding (Losses) Gains on Available-for-Sale Investment Securities [Member] | Accounting Standards Update 2017-12
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption	[1]					0
Net Unrealized Holding (Losses) Gains on Available-for-Sale Investment Securities [Member] | Accounting Standards Update 2016-01
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption							(433)
Net Unrealized Holding (Losses) Gains on Available-for-Sale Investment Securities [Member] | Accounting Standards Update 2018-02
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption							(968)
Net Change Related to Derivative Used for Cash Flow Hedge [Member]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance				81	9
Net Change				(364)	310
Ending balance		(200)	321	(200)	321
Net Change Related to Derivative Used for Cash Flow Hedge [Member] | Accounting Standards Update 2017-12
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption	[1]					83
Net Change Related to Derivative Used for Cash Flow Hedge [Member] | Accounting Standards Update 2016-01
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption							0
Net Change Related to Derivative Used for Cash Flow Hedge [Member] | Accounting Standards Update 2018-02
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption							2
Net Change Related to Defined Benefit Pension Plan [Member]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance				(17,276)	(13,719)
Net Change				392	333
Ending balance		(16,884)	(16,341)	(16,884)	(16,341)
Net Change Related to Defined Benefit Pension Plan [Member] | Accounting Standards Update 2017-12
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption	[1]					0
Net Change Related to Defined Benefit Pension Plan [Member] | Accounting Standards Update 2016-01
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption							0
Net Change Related to Defined Benefit Pension Plan [Member] | Accounting Standards Update 2018-02
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption							(2,955)
Accumulated Other Comprehensive (Loss) Income [Member]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Net Change		$ 2,289	$ (1,216)	$ 6,384	$ (5,882)
Accumulated Other Comprehensive (Loss) Income [Member] | Accounting Standards Update 2017-12
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption	[1],[2]					$ 83
Accumulated Other Comprehensive (Loss) Income [Member] | Accounting Standards Update 2016-01
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption							(433)
Accumulated Other Comprehensive (Loss) Income [Member] | Accounting Standards Update 2018-02
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Cumulative Effect of New Accounting Principle in Period of Adoption							$ (3,921)

[1] (1) See Note 1, "Summary of Significant Accounting Policies - Accounting Pronouncements Adopted in 2019" for additional information.

[2] (1) See Note 1, "Summary of Significant Accounting Policies - Accounting Pronouncements Adopted in 2019" for additional information.