Fair Value Measurements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of estimated obligation	$ 5.6
Decrease in the estimated obligation by a change in the assumed inputs	(12)
Average increase or decrease in sales volume	10.00%
Increase (decrease) in fair value of contingent consideration	3
Cash and cash equivalents	171.2	365.7	147.5	218.3
Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Remaining estimated obligation to be paid under contract	20
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	171.2	365.7
Long-term debt, fair value	$ 2,295.4	$ 2,706.5