Pension Benefits, Other Postretirement Benefits and Employee Savings and Investment Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 0	$ 0
Interest cost	908	5,641	6,758
Expected return of plan assets	(1,574)	(6,932)	(8,662)
Amortization of prior service credit	0	0	0
Amortization of net loss (gain)	427	1,514	1,828
Settlement charge	(63)	53,213	0
Net periodic benefit cost (credit)	(302)	53,436	(76)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	56	61	73
Interest cost	40	59	62
Expected return of plan assets	0	0	0
Amortization of prior service credit	(112)	(1,011)	(1,602)
Amortization of net loss (gain)	0	0	0
Settlement charge	0	0	0
Net periodic benefit cost (credit)	$ (16)	$ (891)	$ (1,467)