Quarterly report pursuant to Section 13 or 15(d)

Income Taxes - Additional Information (Detail)

v2.4.0.8
Income Taxes - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Income Taxes [Line Items]        
Gross unrecognized tax benefit balance, change within the next twelve months, lower limit $ 0   $ 0  
Gross unrecognized tax benefit balance, change within the next twelve months, upper limit $ 6.2   $ 6.2  
Effective income tax rate 35.30% 33.50% 35.70% 35.00%