Schedule Of Consolidated Net Periodic Benefit Costs (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($) pension_plan	Mar. 31, 2015 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of Union Pension Plans | pension_plan	2
Defined Contribution Plan, Cost Recognized	$ 3,000	$ 2,800
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	22,900
Components of net periodic benefit costs:
Service cost	4,688	4,470
Interest cost	2,045	1,869
Expected return on plan assets	(2,128)	(1,896)
Amortization of prior service credit	(45)	0
Amortization of actuarial loss	1,217	1,347
Net periodic benefit cost (credit)	5,777	5,790
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	500
Components of net periodic benefit costs:
Service cost	61	66
Interest cost	110	110
Expected return on plan assets	0	0
Amortization of prior service credit	(928)	(928)
Amortization of actuarial loss	184	225
Net periodic benefit cost (credit)	$ (573)	$ (527)