Derivatives - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Mar. 31, 2013 Fair Value Hedging	Mar. 31, 2012 Fair Value Hedging	Mar. 31, 2013 Senior Notes Eight Point Twenty Five Percent Due March Fifteen Two Thousand Nineteen	Mar. 31, 2012 Senior Notes Eight Point Twenty Five Percent Due March Fifteen Two Thousand Nineteen	Mar. 31, 2012 Senior Notes Four Point Nine Five Percent Due April One Two Thousand Fourteen	Apr. 09, 2010 Senior Notes Four Point Nine Five Percent Due April One Two Thousand Fourteen
Derivative [Line Items]
Derivative, inception date						Mar. 13, 2012		Apr. 09, 2010
Notional amount of interest rate fair value hedge derivatives						$ 400.0			$ 600.0
Debt instrument, face amount						450.0	450.0
Interest rate						8.25%	8.25%	4.95%	4.95%
Maturity date						Mar. 15, 2019	Mar. 15, 2019	Apr. 01, 2014
Terminated portion of interest rate swap agreement, notional amount								342.0
Repayment of debt assumed in acquisition								341.8
Proceeds from termination of interest rate swaps		11.0
Reduction to interest expense	(62.8)	(60.7)		2.3	2.0
Aggregate notional value of foreign exchange forward contracts	$ 515.6		$ 654.2