CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement of Other Comprehensive Income [Abstract]
Net income	$ 372.5	$ 424.2	$ 1,235.5	$ 1,193.1
Other comprehensive income (loss):
Foreign currency translation adjustments	17.9	4.7	22.0	6.8
Change in functional currency of a foreign subsidiary	0	0	0	13.1
Net unrealized gains (losses) related to cash flow hedges:
Unrealized holding gains (losses), net of tax expense (benefit) of ($0.2) and ($1.3) for the three-months ended September 30, 2013 and 2012, respectively, and $0 and ($13.1) for the nine-months ended September 30, 2013 and 2012, respectively.	(89.6)	(26.8)	(3.2)	21.1
Reclassification adjustment for (gains) losses included in net income, net of tax (expense) benefit of $0.3 and $0.6 for the three-months ended September 30, 2013 and 2012, respectively, and $6.5 and ($2.4) for the nine-months ended September 30, 2013 and 2012, respectively.	(11.4)	(24.9)	(11.6)	(59.9)
Net unrealized gains (losses) on marketable securities available for sale:
Unrealized holding gains (losses), net of tax expense (benefit) of $58.5 and $0 for the three-months ended September 30, 2013 and 2012, respectively, and $78.4 and ($0.1) for the nine-months ended September 30, 2013 and 2012, respectively.	104.6	1.7	137.6	3.3
Reclassification adjustment for (gains) losses included in net income, net of tax (expense) benefit of $0.8 and $0 for the three-months ended September 30, 2013 and 2012, respectively, and $1.8 and $0 for the nine-months ended September 30, 2013 and 2012, respectively.	2.2	0.4	4.4	0.1
Total other comprehensive income (loss)	23.7	(44.9)	149.2	(15.5)
Comprehensive income	$ 396.2	$ 379.3	$ 1,384.7	$ 1,177.6