Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income (Loss)) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 640,536
Unrealized gains	(18,721)
Amounts reclassified from AOCI	(122)
Ending Balance	547,782
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	5,689
Ending Balance	(13,154)
Derivative instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(2,564)
Unrealized gains	(2,974)
Amounts reclassified from AOCI	668
Ending Balance	(4,870)
Pension, postretirement and other post-employment benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	8,273
Unrealized gains	(15,953)
Amounts reclassified from AOCI	(650)
Ending Balance	(8,330)
Available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(20)
Unrealized gains	206
Amounts reclassified from AOCI	(140)
Ending Balance	$ 46