Employee Benefit Plans and Other Postretirement Benefits (Components Of Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension and SERPA Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 32,340	$ 31,584	$ 33,437
Interest cost	82,778	85,076	90,827
Expected return on plan assets	(147,671)	(141,385)	(145,781)
Prior service (credit) cost	(420)	1,018	1,019
Net loss	64,773	43,993	46,351
Net curtailment loss (gain)	(1,017)	0	0
Settlement loss	0	0	1,463
Net periodic benefit cost	32,817	20,286	27,316
Postretirement Health Coverage
Defined Benefit Plan Disclosure [Line Items]
Service cost	7,180	7,500	7,478
Interest cost	11,556	13,648	14,814
Expected return on plan assets	(14,161)	(12,623)	(12,069)
Prior service (credit) cost	(1,842)	(2,171)	(2,803)
Net loss	1,817	3,261	3,537
Net curtailment loss (gain)	886	0	0
Settlement loss	0	0	0
Net periodic benefit cost	$ 3,664	$ 9,615	$ 10,957