Retirement Plan (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Pension Contributions	$ 22,700
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements	0	$ 0	$ (37,589)
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest		0
Pension expense		42,600
Defined Contribution Plan, Employer Discretionary Contribution Amount	17,200	16,100	15,500
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements		(39,500)
Transition Benefit Costs	11,000	10,800	12,500
Defined Benefit Post-retirement Health Coverage [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	2,100
Defined Benefit Plan, Expected Future Benefit Payments, Year Two	1,800
Defined Benefit Plan, Expected Future Benefit Payments, Year Three	1,900
Defined Benefit Plan, Expected Future Benefit Payments, Year Four	1,800
Defined Benefit Plan, Expected Future Benefit Payments, Year Five	1,900
Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter	9,200
Retirement Restoration Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension expense	100	1,200	$ 400
Accrued liability	2,800	$ 3,000
Projected benefit obligations under this plan	2,800
Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months	$ 200