Debt (Cash Convertible Notes) (Narrative) (Details) $ / shares in Units, shares in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 24, 2013 USD ($)	Sep. 15, 2011 $ / shares shares	Nov. 09, 2010	Sep. 15, 2008 USD ($) $ / shares shares
Debt Instrument [Line Items]
Face amount of debt					$ 750.0
Debt instrument, interest rate, stated percentage							6.00%
Effective interest rate		0.74%
Proceeds from convertible note hedge		$ 1,970.8	$ 0.0	$ 0.0
Old Warrants
Debt Instrument [Line Items]
Warrants exchanged in amended transaction | shares						41.0
Exercise price of warrants issued | $ / shares								$ 20.00
Old Warrants | Maximum
Debt Instrument [Line Items]
Number of common stock issuable for warrants | shares								43.2
New Warrants
Debt Instrument [Line Items]
Exercise price of warrants issued | $ / shares						$ 30
Purchased cash convertible note hedge
Debt Instrument [Line Items]
Proceeds from convertible note hedge		$ 1,970.0
Convertible Debt | Cash Convertible Notes
Debt Instrument [Line Items]
Face amount of debt			$ 573.1					$ 575.0
Debt instrument, interest rate, stated percentage	[1]							3.75%
Effective interest rate		9.50%
Total redemption amount		$ 2,540.0

[1] The Cash Convertible Notes matured on September 15, 2015 and the remaining amount outstanding was repaid in full by the Company utilizing proceeds from the Delayed Draw Loan, included in 2015 Term Loans above. In addition, the convertible note hedge was settled during the third quarter of 2015.