Acquisitions and Divestitures - Unaudited Pro Forma Results of Operations (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012
Income Statement [Abstract]
Net revenues	$ 2,003.3	$ 4,150.6
Net income attributable to common shareholders	$ (78.8)	$ (73.5)
Earnings (loss) per share:
Basic	$ (0.60)	$ (0.56)
Diluted	$ (0.60)	$ (0.56)