Pension Benefits and Other Postretirement Benefits (Components of Net Periodic Benefit (Credit) Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Settlement benefit	$ 534	$ 0	$ 534	$ 55
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	0
Interest cost	182	223	550	685
Expected return of plan assets	(389)	(394)	(1,169)	(1,180)
Amortization of prior service credit	0	0	0	0
Amortization of net loss	95	99	291	327
Settlement benefit	0	0	0	(63)
Net periodic benefit (credit) cost	(112)	(72)	(328)	(231)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	16	17	46	51
Interest cost	7	10	19	30
Expected return of plan assets	0	0	0	0
Amortization of prior service credit	(25)	(28)	(73)	(84)
Amortization of net loss	0	0	0	0
Settlement benefit	0	0	0	0
Net periodic benefit (credit) cost	$ (2)	$ (1)	$ (8)	$ (3)