Comprehensive Income/Loss (Comprised of the following Components) (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018		Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior Period Reclassification Adjustment	[1]					$ 0
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 0	[2]	$ 177	[3]	0	[2]	$ 177	[3]
Beginning Balance						(1,831)		(1,337)
Net change in other comprehensive income (loss)		(2,550)		375		(9,605)		1,753
Ending Balance		(12,664)		416		(12,664)		416
Unrealized Gain on Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior Period Reclassification Adjustment						(111)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		(831)				(831)
Beginning Balance						(504)		173
Net change in other comprehensive income (loss)						(9,654)		1,511
Ending Balance		(11,100)		1,684		(11,100)		1,684
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior Period Reclassification Adjustment						205
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		0				0
Beginning Balance						948		361
Net change in other comprehensive income (loss)						(170)		116
Ending Balance		983		477		983		477
Deferred Gain on Hedge Transactions
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior Period Reclassification Adjustment						29
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		0				0
Beginning Balance						137		281
Net change in other comprehensive income (loss)						(132)		(108)
Ending Balance		34		173		34		173
Defined Benefit Postretirement Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior Period Reclassification Adjustment						(520)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		0				0
Beginning Balance						(2,412)		(2,152)
Net change in other comprehensive income (loss)						351		234
Ending Balance		(2,581)		$ (1,918)		(2,581)		(1,918)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior Period Reclassification Adjustment	[2]					(397)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	[1]	$ (831)				(831)
Net change in other comprehensive income (loss)						$ (9,605)		$ 1,753

[1] Represents adjustment needed to reflect the cumulative impact on retained earnings for the classification and measurement of investments in equity securities. Pursuant to the Company's adoption of Accounting Standards Update 2016-01, the Company's investments in equity securities will no longer be classified as available for sale, therefore the Company was required to reclassify the net unrealized gain recognized on the change in fair value of these equity securities from other comprehensive income to retained earnings.

[2] Represents adjustment needed to reflect the cumulative impact on retained earnings for reclassification of the income tax effects attributable to accumulated other comprehensive income, as a result of the Tax Cuts and Jobs Act (the "Tax Act"). Pursuant to the Company's adoption of Accounting Standards Update 2018-02, the Company has elected to reclassify amounts stranded in other comprehensive income to retained earnings.

[3] Represents adjustment needed to reflect the cumulative impact on retained earnings for previously recognized stock based compensation, which included an adjustment for estimated forfeitures. Pursuant to the Company's adoption of Accounting Standards Update 2016-09, the Company has elected to recognize stock based compensation without inclusion of a forfeiture estimate, and as such has recognized this adjustment to present retained earnings consistent with this election.