Share-Based Compensation (Movements On Share Awards Priced In U.S. Dollars) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Time Vested [Member]
Unvested at the beginning of period	17.3	17.4
Granted during the period	5.5	5.6
Forfeited during the period	(0.3)	(0.3)
Vested and distributed during the period	(5.6)	(5.2)
Unvested at the end of the period	16.9	17.5
Performance-Vested [Member]
Unvested at the beginning of period	0	0.1
Granted during the period	0
Forfeited during the period	0
Vested and distributed during the period	0	(0.1)
Unvested at the end of the period	0	0
Weighted Average Grant Date Fair Value $ [Member]
Unvested at the beginning of period Weighted Average Grant Date Fair Value	20.34	17.25
Granted during period Weighted Average Grant Date Fair Value	24.84	26.74
Forfeited during the period	21.07	19.36
Vested and distributed during the period Weighted Average Grant Date Fair Value	18.87	18.90
Unvested at the end of the period Weighted Average Grant Date Fair Value	22.31	20.25