Schedule Of Consolidated Net Periodic Benefit Costs (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) pension_plan	Jun. 30, 2015 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of Union Pension Plans | pension_plan			2
Defined Contribution Plan, Cost Recognized	$ 2,400	$ 2,200	$ 5,400	$ 5,000
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	4,405	4,975	9,093	9,445
Interest cost	1,933	2,008	3,978	3,877
Expected return on plan assets	(2,331)	(2,123)	(4,459)	(4,019)
Amortization of prior service credit	(45)	0	(90)	0
Amortization of actuarial loss	1,107	1,806	2,324	3,153
Net periodic benefit cost (credit)	5,069	6,666	10,846	12,456
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year			600
Components of net periodic benefit costs:
Service cost	62	56	123	122
Interest cost	110	109	220	219
Expected return on plan assets	0	0	0	0
Amortization of prior service credit	(929)	(928)	(1,857)	(1,856)
Amortization of actuarial loss	185	217	369	442
Net periodic benefit cost (credit)	$ (572)	$ (546)	$ (1,145)	$ (1,073)