Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Income and Comprehensive Income [Abstract]
Net income	$ 665.1	$ 745.4	$ 865.0
Other comprehensive income:
Foreign currency translation adjustments	25.3	23.7	(24.0)
Unrealized holding (loss)/gain on available-for-sale securities (net of taxes of $0.1 million, $2.5 million and $0.2 million)	(2.0)	2.9	16.2
Other than temporary impairment of available-for-sale securities (net of taxes of $nil in all periods)	0	0	2.4
Realized gain on divestment of available-for-sale securities (net of taxes of $nil, $nil million and $3.5 million)	0	0	(20.0)
Comprehensive income	688.4	772.0	839.6
Components of accumulated other comprehensive income
Foreign currency translation adjustments	110.4	85.1
Unrealized holding (loss)/gain on available-for-sale securities, net of taxes	(0.2)	1.8
Accumulated other comprehensive income	$ 110.2	$ 86.9