Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Income Tax Contingency [Line Items]
Effective tax rate attributable to continuing operations	34.20%	26.70%	29.40%	30.40%
Increase in unrecognized tax benefits			$ 6.0
Gross accrued interest and penalties on unrecognized tax benefits	0.7		0.7		0.9
Unrecognized income tax benefits that, if recognized, would affect the effective tax rates	2.7		2.7		8.8
Unrecognized income tax benefits that, if recognized, would affect the effective tax rates , interest and penalties	$ 0.5		$ 0.5		$ 0.7