Employee Benefit Plans And Other Postretirement Benefits (Schedule Of Obligation And Funded Status) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension and SERPA Benefits [Member]
Change in benefit obligation:
Benefit obligation, beginning of period	$ 2,069,980	$ 1,714,650
Service cost	40,039	31,498	$ 35,987
Interest cost	87,345	86,923	79,248
Actuarial (gains) losses	(128,082)	309,542
Defined Benefit Plan, Plan Amendments	6,407	0
Plan participant contributions	0	0
Benefits paid, net of Medicare Part D subsidy	(77,252)	(72,633)
Benefit obligation, end of period	2,009,000	2,069,980	1,714,650
Change in plan assets:
Fair value of plan assets, beginning of period	1,992,646	1,920,601
Actual return on plan assets	(77,980)	143,040
Company contributions	4,553	1,638
Plan participant contributions	0	0
Benefits paid	(77,252)	(72,633)
Fair value of plan assets, end of period	1,841,967	1,992,646	1,920,601
Funded status of the plans, December 31	(167,033)	(77,334)
Accrued benefit liability (current liabilities)	(2,145)	(1,148)
Accrued benefit liability (long-term liabilities)	(164,888)	(76,186)
Net amount recognized	(167,033)	(77,334)
Postretirement Healthcare Benefits [Member]
Change in benefit obligation:
Benefit obligation, beginning of period	361,006	366,524
Service cost	8,259	7,015	7,858
Interest cost	14,166	16,878	15,599
Actuarial (gains) losses	(6,757)	(2,870)
Defined Benefit Plan, Plan Amendments	0	0
Plan participant contributions	2,587	2,368
Benefits paid, net of Medicare Part D subsidy	(25,144)	(28,909)
Benefit obligation, end of period	354,739	361,006	366,524
Change in plan assets:
Fair value of plan assets, beginning of period	156,840	147,875
Actual return on plan assets	(75)	8,965
Company contributions	23,937	28,048
Plan participant contributions	2,587	2,368
Benefits paid	(26,524)	(30,416)
Fair value of plan assets, end of period	156,765	156,840	$ 147,875
Funded status of the plans, December 31	(197,974)	(204,166)
Accrued benefit liability (current liabilities)	(4,315)	(1,160)
Accrued benefit liability (long-term liabilities)	(193,659)	(203,006)
Net amount recognized	$ (197,974)	$ (204,166)