Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at the beginning of the period			$ (49.7)	$ (62.3)
Other comprehensive income before reclassifications			156.4	44.3
Amounts reclassified from accumulated other comprehensive income			(7.2)	(59.8)
Total other comprehensive income (loss)	23.7	(44.9)	149.2	(15.5)
Balance at the end of the period	99.5	(77.8)	99.5	(77.8)
Pension Liability
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at the beginning of the period			(10.1)	(5.4)
Other comprehensive income before reclassifications			0	0
Amounts reclassified from accumulated other comprehensive income			0	0
Total other comprehensive income (loss)			0	0
Balance at the end of the period	(10.1)	(5.4)	(10.1)	(5.4)
Net Unrealized Gains (Losses) From Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at the beginning of the period			4.2	1.8
Other comprehensive income before reclassifications			137.6	3.3
Amounts reclassified from accumulated other comprehensive income			4.4	0.1
Total other comprehensive income (loss)			142.0	3.4
Balance at the end of the period	146.2	5.2	146.2	5.2
Net Unrealized Gains (Losses) From Hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at the beginning of the period			(16.1)	8.7
Other comprehensive income before reclassifications			(3.2)	21.1
Amounts reclassified from accumulated other comprehensive income			(11.6)	(59.9)
Total other comprehensive income (loss)			(14.8)	(38.8)
Balance at the end of the period	(30.9)	(30.1)	(30.9)	(30.1)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at the beginning of the period			(27.7)	(67.4)
Other comprehensive income before reclassifications			22.0	19.9
Amounts reclassified from accumulated other comprehensive income			0	0
Total other comprehensive income (loss)			22.0	19.9
Balance at the end of the period	$ (5.7)	$ (47.5)	$ (5.7)	$ (47.5)