Employee Benefit Plans and Other Postretirement Benefits (Components Of Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Postretirement Health Coverage
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 7,478	$ 8,259	$ 7,015
Interest cost	14,814	14,166	16,878
Special early retirement benefits	0	622	0
Expected return on plan assets	(12,069)	(11,506)	(10,429)
Prior service cost (credit)	(2,803)	(3,217)	(3,853)
Net loss	3,537	3,971	4,729
Settlement loss	0	0	0
Net periodic benefit cost	10,957	12,295	14,340
Pension and SERPA Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	33,437	40,039	31,498
Interest cost	90,827	87,345	86,923
Special early retirement benefits	0	10,563	0
Expected return on plan assets	(145,781)	(144,929)	(136,734)
Prior service cost (credit)	1,019	435	1,119
Net loss	46,351	54,709	36,563
Settlement loss	1,463	368	0
Net periodic benefit cost	$ 27,316	$ 48,530	$ 19,369