Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 283,561
Ending Balance	414,643
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(35,701)
Unrealized gains (losses)	6,709
Amounts reclassified from AOCI	1,835
Ending Balance	(27,157)
Derivative instruments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(3,891)
Unrealized gains (losses)	35
Amounts reclassified from AOCI	1,591
Ending Balance	(2,265)
Pension, postretirement and other post-employment benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(31,459)
Unrealized gains (losses)	6,429
Amounts reclassified from AOCI	269
Ending Balance	(24,761)
Available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(351)
Unrealized gains (losses)	245
Amounts reclassified from AOCI	(25)
Ending Balance	$ (131)