Shareholders' Equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Jun. 30, 2012	Sep. 30, 2012	Dec. 31, 2011	Nov. 03, 2011	Dec. 31, 2010
Components of Accumulated Other Comprehensive Income (Loss) [Abstract]
Foreign currency translation gain (loss)	$ 159.5		$ 159.5	$ 186.6
Translation loss on net investment hedge, net of tax	(39.3)		(39.3)	(43.2)
Translation loss on long-term intercompany loans	(71.4)		(71.4)	(89.1)
Unrealized gain on investments, net of tax	11.4		11.4	8.2
Defined benefit pension plans, net of tax	(25.8)		(25.8)	(26.5)
Retiree health care plan, net of tax	(0.7)		(0.7)	(0.7)
Accumulated other comprehensive income	33.7		33.7	35.3
Translation loss on net investment hedge, tax	(24.1)		(24.1)	(26.5)
Unrealized gain on investments, tax	3.8		3.8	2.8
Defined benefit pension plans, tax	(19.2)		(19.2)	(19.5)
Retiree health care plan, tax	$ (0.5)		$ (0.5)	$ (0.5)
Share Repurchase Programs [Line Items]
Shares authorized to be repurchased (in shares)	6,000,000		6,000,000		3,000,000	3,000,000
Shares repurchased (in shares)			1,178,897
Dividend declaration date	Oct. 31, 2012	May 02, 2012
Dividend paid (in dollars per share)		$ 0.43
Dividends payable (in dollars per share)	$ 0.43		$ 0.43
Dividends Paid, Date Paid		Jun. 15, 2012
Dividends Payable, Date Payable	Dec. 14, 2012
Dividends Payable, Date of Record	Dec. 04, 2012	Jun. 01, 2012
Authorized in 2010 [Member]
Share Repurchase Programs [Line Items]
Shares repurchased (in shares)			619,257
Shares authorized to be repurchased remaining (in shares)	0		0
Authorized in 2011 [Member]
Share Repurchase Programs [Line Items]
Shares repurchased (in shares)			559,640
Shares authorized to be repurchased remaining (in shares)	2,400,000		2,400,000
Shares repurchased but not settled (in shares)	450,000		450,000
Price for repurchased but unsettled shares	$ 16.9		$ 16.9