CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 597.8	$ 478.1	$ 877.5	$ 863.0
Other comprehensive income (loss):
Foreign currency translation adjustments	1.1	10.0	4.1	4.1
Net unrealized gains (losses) related to cash flow hedges:
Unrealized holding gains (losses), net of tax expense (benefit) of ($8.9) and $0 for the three-months ended June 30, 2014, and 2013, respectively, and ($12.6) and $0.2 for the six-months ended June 30, 2014, and 2013, respectively.	(12.8)	11.5	(27.7)	86.4
Reclassification adjustment for (gains) losses included in net income, net of tax (expense) benefit of $0.4 and $2.8 for the three-months ended June 30, 2014 and 2013, respectively, and $0.7 and $6.2 for the six-months ended June 30, 2014 and 2013, respectively.	2.6	(4.0)	4.2	(0.2)
Net unrealized gains (losses) on marketable securities available for sale:
Unrealized holding gains (losses), net of tax expense (benefit) of $16.1 and $19.9 for the three-months ended June 30, 2014 and 2013, respectively, and $45.1 and $19.9 for the six-months ended June 30, 2014 and 2013, respectively.	31.9	34.9	87.2	33.0
Reclassification adjustment for (gains) losses included in net income, net of tax (expense) benefit of $0.6 and $1.0 for the three-months ended June 30, 2014 and 2013, respectively, and $1.1 and $1.0 for the six-months ended June 30, 2014 and 2013.	1.0	1.4	1.9	2.2
Total other comprehensive income (loss)	23.8	53.8	69.7	125.5
Comprehensive income	$ 621.6	$ 531.9	$ 947.2	$ 988.5