Stock-Based Compensation (Summary Of Stock Option Activity) (Details) - Stock Options [Member] - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, Outstanding at January 1, Number of Shares	3,622,000	3,313,000	3,650,000
Stock options, Granted, Number of Shares	2,401,000	835,000	571,000
Stock options, Exercised, Number of Shares	0	(402,000)	(833,000)
Stock options, Forfeited or expired, Number of Shares	(400,000)	(124,000)	(75,000)
Stock options, Outstanding at December 31, Number of Shares	5,623,000	3,622,000	3,313,000
Stock options, Outstanding at January 1, Weighted Average Exercise Price	$ 35.41	$ 35.70	$ 29.84
Stock options, Granted, Weighted Average Exercise Price	9.47	32.31	38.95
Stock options, Exercised, Weighted Average Exercise Price		30.60	12.12
Stock options, Forfeited or expired, Weighted Average Exercise Price	32.20	37.80	37.31
Stock options, Outstanding at December 31, Weighted Average Exercise Price	$ 24.57	$ 35.41	$ 35.70