Schedule Of Consolidated Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pension Plan [Member]
Components of net periodic benefit costs:
Service cost	$ 6,358	$ 6,269	$ 12,885	$ 21,969
Interest cost	3,110	2,795	6,110	9,238
Expected return on plan assets	(2,317)	(3,024)	(4,691)	(6,002)
Amortization of prior service credit	(45)	(46)	(90)	(91)
Amortization of actuarial loss	1,508	1,569	2,785	6,523
Settlement cost	2,060	0	2,060	0
Net periodic benefit cost	10,674	7,563	19,059	31,637
Other Postretirement Benefits Plan [Member]
Components of net periodic benefit costs:
Service cost	43	51	97	116
Interest cost	135	102	254	208
Expected return on plan assets	0	0	0	0
Amortization of prior service credit	0	0	0	0
Amortization of actuarial loss	117	134	188	294
Settlement cost	0	0	0	0
Net periodic benefit cost	$ 295	$ 287	$ 539	$ 618