Comprehensive Income/Loss (Comprised of the following Components) (Details) - USD ($) $ in Thousands		3 Months Ended					6 Months Ended
		Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018		Jun. 30, 2019	Jun. 30, 2018
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	[1]				0
Beginning Balance			$ (1,173)		(1,831)		$ (1,173)	$ (1,831)
Net change in other comprehensive income (loss)		$ 14,075	8,054	$ (1,919)	(5,136)		22,129	(7,055)
Ending Balance		20,956		(10,114)			20,956	(10,114)
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			(5,947)		(504)		(5,947)	(504)
Net change in other comprehensive income (loss)							10,174	(7,392)
Ending Balance		4,227		(8,838)			4,227	(8,838)
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			6,148		948		6,148	948
Net change in other comprehensive income (loss)							11,875	191
Ending Balance		18,023		1,344			18,023	1,344
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			0		137		0	137
Net change in other comprehensive income (loss)							0	(88)
Ending Balance		0		78			0	78
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			(1,374)		(2,412)		(1,374)	(2,412)
Net change in other comprehensive income (loss)							80	234
Ending Balance		(1,294)		(2,698)			$ (1,294)	(2,698)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Prior Period Reclassification Adjustment					(397)	[2]		$ (397)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	[1]				(831)
Net change in other comprehensive income (loss)		$ 14,075	$ 8,054	$ (1,919)	$ (5,136)

[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.