Pension Benefits and Other Postretirement Benefits (Components of Net Periodic Benefit (Credit) Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Settlement benefit	$ 0	$ 55	$ 0	$ 55
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	184	231	368	462
Expected return of plan assets	(390)	(393)	(780)	(786)
Amortization of prior service credit	0	0	0	0
Amortization of net loss	98	114	196	228
Settlement benefit	0	(63)	0	(63)
Net periodic benefit (credit) cost	(108)	(111)	(216)	(159)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	15	17	30	34
Interest cost	6	10	12	20
Expected return of plan assets	0	0	0	0
Amortization of prior service credit	(24)	(28)	(48)	(56)
Amortization of net loss	0	0	0	0
Settlement benefit	0	0	0	0
Net periodic benefit (credit) cost	$ (3)	$ (1)	$ (6)	$ (2)