Reserves for Discounts and Allowances (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Analysis of the amount of, and change in, reserves
Balance, as of December 31, 2012	$ 237.1
Current provisions relating to sales in current year	176.6
Adjustments relating to prior years	2.5
Payments/returns relating to sales in current year	(63.5)
Payments/returns relating to sales in prior years	(100.3)
Balance, as of March 31, 2013	252.4
Discounts [Member]
Analysis of the amount of, and change in, reserves
Balance, as of December 31, 2012	15.5
Current provisions relating to sales in current year	35.6
Adjustments relating to prior years	(0.8)
Payments/returns relating to sales in current year	(19.3)
Payments/returns relating to sales in prior years	(13.1)
Balance, as of March 31, 2013	17.9
Contractual Adjustments [Member]
Analysis of the amount of, and change in, reserves
Balance, as of December 31, 2012	194.8
Current provisions relating to sales in current year	137.3
Adjustments relating to prior years	3.1
Payments/returns relating to sales in current year	(44.2)
Payments/returns relating to sales in prior years	(83.3)
Balance, as of March 31, 2013	207.7
Returns [Member]
Analysis of the amount of, and change in, reserves
Balance, as of December 31, 2012	26.8
Current provisions relating to sales in current year	3.7
Adjustments relating to prior years	0.2
Payments/returns relating to sales in current year	0
Payments/returns relating to sales in prior years	(3.9)
Balance, as of March 31, 2013	$ 26.8