Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Income Taxes [Line Items]
Effective income tax rate	27.80%	30.70%
Increase/decrease in effective tax rate due to impact of discrete tax items	0.50%	1.70%
Unrecognized tax benefits, increases resulting from current and prior period tax positions	$ 2.6
Total unrecognized tax benefits	23.1
Unrecognized tax payable, current	2.3
Unrecognized tax payable, non-current	$ 20.8