Employee Benefit Plans (Amounts Included In Accumulated Other Comprehensive Loss That Have Not Yet Been Recognized In Net Periodic Benefit Expense) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial gain (loss)		$ (524,414)	$ (413,879)
Prior-service credit (cost)		(40,809)	(42,428)
Amount included in accumulated other comprehensive loss, not yet recognized in net periodic benefit		565,223	456,307
Reclassification of actuarial loss to net periodic benefit expense (income)	12,494
Reclassification of prior-service cost to net periodic benefit expense (income)	1,619
Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial gain (loss)		(35,673)	(27,367)
Prior-service credit (cost)		(99)	(104)
Amount included in accumulated other comprehensive loss, not yet recognized in net periodic benefit		35,772	27,471
Reclassification of actuarial loss to net periodic benefit expense (income)	1,184
Reclassification of prior-service cost to net periodic benefit expense (income)	5
Postretirement Medical Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Actuarial gain (loss)		8,508	19,537
Prior-service credit (cost)		16,503	19,366
Amount included in accumulated other comprehensive loss, not yet recognized in net periodic benefit		(25,011)	(38,903)
Reclassification of actuarial loss to net periodic benefit expense (income)		265
Reclassification of prior-service cost to net periodic benefit expense (income)		$ 2,455