Stockholders' Equity (Changes In Accumulated Other Comprehensive Loss By Component) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 10,003,100,000	$ 10,945,200,000	$ 9,052,600,000
Amounts reclassified from AOCI	23,200,000	6,300,000
Net current period AOCI	53,600,000	2,000,000	(8,200,000)
Ending balance	7,320,000,000	10,003,100,000	10,945,200,000
Total AOCI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(140,100,000)	(142,100,000)	(133,900,000)
AOCI activity before reclassifications	30,400,000	(4,300,000)
Amounts reclassified from AOCI	23,200,000	6,300,000
Net current period AOCI	53,600,000	2,000,000	(8,200,000)
Ending balance	(86,500,000)	(140,100,000)	(142,100,000)
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(61,400,000)	(65,700,000)
AOCI activity before reclassifications	27,200,000	(400,000)
Amounts reclassified from AOCI	26,200,000	4,700,000	80,500,000
Net current period AOCI	53,400,000	4,300,000
Ending balance	(8,000,000)	(61,400,000)	(65,700,000)
Changes in benefit plan net gain (loss) and prior service (cost) credit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(65,300,000)	(69,300,000)
AOCI activity before reclassifications	10,100,000	2,400,000
Amounts reclassified from AOCI	700,000	1,600,000	2,000,000
Net current period AOCI	10,800,000	4,000,000
Ending balance	(54,500,000)	(65,300,000)	(69,300,000)
Unrealized net gains (losses) on available for sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(13,400,000)	(7,100,000)
AOCI activity before reclassifications	(6,900,000)	(6,300,000)
Amounts reclassified from AOCI	(3,700,000)	0
Net current period AOCI	(10,600,000)	(6,300,000)
Ending balance	$ (24,000,000)	$ (13,400,000)	$ (7,100,000)