Schedule Of Consolidated Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension Plan [Member]
Components of net periodic benefit costs:
Service cost	$ 6,527	$ 15,700
Interest cost	3,000	6,443
Expected return on plan assets	(2,374)	(2,978)
Amortization of prior service credit	(45)	(45)
Amortization of actuarial loss	1,277	4,954
Net periodic benefit cost	8,385	24,074
Other Postretirement Benefits Plan [Member]
Components of net periodic benefit costs:
Service cost	54	65
Interest cost	119	106
Expected return on plan assets	0	0
Amortization of prior service credit	0	0
Amortization of actuarial loss	71	160
Net periodic benefit cost	$ 244	$ 331