Debt and Credit Facilities (Narrative) (Details) (USD $) Share data in Millions, unless otherwise specified	9 Months Ended		9 Months Ended		9 Months Ended				9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Four Year Revolving Credit Facility [Member]	Sep. 30, 2012 Three Year Revolving Credit Facility [Member]	Sep. 30, 2012 Five Year Revolving Credit Facility [Member]	Sep. 30, 2012 Exchangeable Senior Notes [Member]	Dec. 31, 2011 Exchangeable Senior Notes [Member]	Apr. 30, 2009 Exchangeable Senior Notes [Member]	Sep. 30, 2012 Debentures With Put Feature [Member]	Oct. 15, 2012 Debentures With Put Feature [Member]	Feb. 15, 2012 Debentures With Put Feature [Member]	Dec. 31, 2011 Debentures With Put Feature [Member]
Commercial Paper	$ 64,000,000	$ 0
Short-term borrowings and current maturities of long-term debt	1,024,600,000	763,300,000				0	341,200,000		343,600,000			343,600,000
Debt instrument, maturity date range, start									Jan. 01, 2027
Debt instrument, maturity date range, end									Dec. 31, 2028
Debentures with put option available to be exercised										306,400,000	37,200,000
Debentures with put feature, put option, amount exercised										600,000
Senior note issued								345,000,000
Stated interest rate for debt instruments								4.50%
Portion of convertible debt allocated to debt								305,000,000
Portion of convertible debt allocated to equity, gross								40,000,000
Portion of convertible debt allocated to equity, net of allocated fees								39,000,000
Principal repayment, settlement of Exchangeable Senior Notes	(4,500,000)					357,000,000
Ordinary shares issued, shares, Exchangeable Senior Notes (in millions)						10.8
Line of credit facilities, amounts expired				1,000,000,000
Line of credit facility, amount outstanding	$ 2,000,000,000		$ 1,000,000,000		$ 1,000,000,000
Line of credit facility, expiration date			May 20, 2015		Mar. 15, 2017