Accumulated Other Comprehensive Loss (Reclassifications) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Gains (losses) on cash flow hedges
Revenues		$ 844,589	$ 890,681
Interest expense, net		(19,301)	(24,064)
Benefit for income tax		37,024	50,547
Net income		62,640	85,206
Pension and Postretirement Benefit Plans
Settlements	[1],[2]	(1,098)	0
Benefit for income tax		3,799	4,167
Reclassification out of Accumulated Other Comprehensive Loss
Gains (losses) on cash flow hedges
Revenues	[1]	(380)	(396)
Cost of sales	[1]	225	(395)
Interest expense, net	[1]	(507)	(507)
Total before tax	[1]	(662)	(1,298)
Benefit for income tax	[1]	(258)	(502)
Net income	[1]	(404)	(796)
Gains (losses) on available for sale securities
Interest expense, net	[1]	18	(24)
Provision (benefit) for income tax	[1]	7	(9)
Net of tax	[1]	11	(15)
Pension and Postretirement Benefit Plans
Transition credit	[1],[2]	2	2
Prior service costs	[1],[2]	(42)	(59)
Actuarial losses	[1],[2]	(9,409)	(11,519)
Total before tax	[1],[2]	(10,547)	(11,576)
Benefit for income tax	[1],[2]	(3,799)	(4,167)
Net of tax	[1],[2]	$ (6,748)	$ (7,409)

[1] Amounts in parentheses indicate reductions to income and increases to other comprehensive income (loss).

[2] Reclassified from accumulated other comprehensive loss into selling, general and administrative expenses. These amounts are included in the computation of net periodic costs (see Note 10 for additional details).