Other Income, Net (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012		Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other Nonoperating Income (Expense) [Abstract]
Gains on sales of businesses and investments										$ 88.2	$ 125.9	$ 4.3
Vendor discounts and credit adjustments										15.3	19.4	12.7
Other (expense) income, net										(3.0)	4.9	(4.1)
Total other income, net	95.4	1.7	[1]	4.7	(1.3)	13.9	137.1	5.3	(6.1)	100.5	150.2	12.9
Net proceeds from sale of portion of Facebook										94.8	133.5
Gain on sale of portion of Facebook										$ 93.6	$ 132.2

[1] The three months ended December 31, 2012 and the three months ended September 30, 2011, include a pre-tax gain of $93.6 and $132.2, respectively, related to the sale of our holdings in Facebook.