Schedule Of Consolidated Net Periodic Benefit Costs (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) pension_plan	Sep. 30, 2014 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of Union Pension Plans | pension_plan			2
Defined Contribution Plan, Cost Recognized	$ 1,800	$ 1,700	$ 6,800	$ 6,300
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year			21,100
Components of net periodic benefit costs:
Service cost	4,723	3,348	14,168	10,052
Interest cost	1,938	1,332	5,815	5,021
Expected return on plan assets	(2,009)	(1,588)	(6,028)	(4,775)
Amortization of prior service credit	0	0	0	33
Amortization of actuarial loss	1,577	756	4,730	2,315
Settlement cost	0	30	0	1,599
Net periodic benefit cost (credit)	6,229	3,878	18,685	14,245
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year			1,200
Components of net periodic benefit costs:
Service cost	61	57	183	171
Interest cost	109	126	328	379
Expected return on plan assets	0	0	0	0
Amortization of prior service credit	(928)	(928)	(2,784)	(2,784)
Amortization of actuarial loss	221	229	663	686
Settlement cost	0	0	0	0
Net periodic benefit cost (credit)	$ (537)	$ (516)	$ (1,610)	$ (1,548)