Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021 USD ($)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 283,561
Ending Balance	318,529
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(35,701)
Unrealized gains (losses)	4,583
Amounts reclassified from AOCI	1,338
Ending Balance	(29,780)
Derivative instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(3,891)
Unrealized gains (losses)	71
Amounts reclassified from AOCI	1,256
Ending Balance	(2,564)
Pension, postretirement and other post-employment benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(31,459)
Unrealized gains (losses)	4,404
Amounts reclassified from AOCI	106
Ending Balance	(26,949)
Available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(351)
Unrealized gains (losses)	108
Amounts reclassified from AOCI	(24)
Ending Balance	$ (267)