Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Statement of Income and Comprehensive Income [Abstract]
Net income	$ 227.2	$ 192.9	$ 703.4	$ 609.7
Other comprehensive income:
Foreign currency translation adjustments	22.7	(95.6)	5.0	4.6
Unrealized holding gain/(loss) on available-for-sale securities (net of taxes of $0.8 million, $0.3 million, $3.7 million and $0.2 million)	1.2	(0.2)	7.2	15.8
Other than temporary impairment of available-for-sale securities (net of taxes of $nil in all periods)	0	0	0	2.4
Realized gain on divestment of available-for-sale securities (net of taxes of $nil, $3.5 million, $nil and $3.5 million)	0	(20.0)	0	(20.0)
Comprehensive income	251.1	77.1	715.6	612.5
Components of accumulated other comprehensive income
Foreign currency translation adjustments	66.4		66.4
Unrealized holding gain/(loss) on available-for-sale securities, net of taxes	6.1		6.1
Accumulated other comprehensive income	$ 72.5		$ 72.5