Income Taxes Narrative (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Gain on sale of portion of Facebook	$ 93.6	$ 132.2
One hundred percent valuation allowance	100.00%
Operating loss carryforwards	1,356.6
Undistributed foreign earnings	2,110.0	1,766.7
Unrecognized tax benefits	194.6	161.0	146.7	160.5
Unrecognized tax benefits that would impact effective tax rate	193.5
Income tax penalties and interest accrued	13.5	12.1
Income tax penalties and interest expense	1.4	(0.2)
Estimated unrecognized tax benefit decrease, lower bound	30.0
Estimated unrecognized tax benefit decrease, upper bound	40.0
Domestic country
Operating loss carryforwards	15.1
Operating loss carryforwards, expiration date	expire in the years 2026 through 2029
Domestic country | Minimum [Member]
Income tax examination year	2007
Open tax years	2009
Domestic country | Maximum [Member]
Income tax examination year	2008
State and local jurisdiction | Minimum [Member]
Open tax years	1999
Foreign country
Operating loss carryforwards	1,341.5
Operating loss carryforwards, expiration date	expiration periods from 2013 through 2031
Operating loss carryforwards, no expiration	1,091.1
Operating loss carryforwards, subject to expiration	$ 250.4
Foreign country | Minimum [Member]
Open tax years	2005