Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Components of net periodic benefit cost [Abstract]
Contribution made to pension and postretirement plans			$ 0
Pension Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	$ 10	$ 8	31	$ 25
Interest cost	311	299	933	898
Expected return on plan assets	(702)	(753)	(2,108)	(2,259)
Amortization of net loss (gain)	14	0	44	0
Amortization of prior service cost	0	0	0	0
Net periodic benefit	(367)	(446)	(1,100)	(1,336)
Other Postretirement Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	17	0	49	52
Interest cost	60	47	180	156
Expected return on plan assets	(248)	(323)	(743)	(704)
Amortization of net loss (gain)	(49)	(189)	(147)	(367)
Amortization of prior service cost	(83)	(73)	(250)	(28)
Net periodic benefit	$ (303)	$ (538)	$ (911)	$ (891)