Schedule Of Consolidated Net Periodic Benefit Costs (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) pension_plan	Sep. 30, 2015 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Number of Union Pension Plans | pension_plan			2
Defined Contribution Plan, Cost Recognized	$ 2,400	$ 1,800	$ 7,800	$ 6,800
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year			26,000
Components of net periodic benefit costs:
Service cost	4,555	4,723	13,648	14,168
Interest cost	1,992	1,938	5,970	5,815
Expected return on plan assets	(2,235)	(2,009)	(6,694)	(6,028)
Amortization of prior service credit	(45)	0	(135)	0
Amortization of actuarial loss	1,161	1,577	3,485	4,730
Settlement cost	202	0	202	0
Net periodic benefit cost (credit)	5,630	6,229	16,476	18,685
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	53	61	176	183
Interest cost	148	109	368	328
Expected return on plan assets	0	0	0	0
Amortization of prior service credit	(928)	(928)	(2,785)	(2,784)
Amortization of actuarial loss	291	221	660	663
Settlement cost	0	0	0	0
Net periodic benefit cost (credit)	$ (436)	$ (537)	$ (1,581)	$ (1,610)