Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v2.4.0.8
Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Jun. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Significant Accounting Policies [Line Items]          
Effective tax rate from continuing operations 36.30% 38.60%   37.80% 34.80%
Tax benefit from state tax settlement     $ 3.6    
Maximum [Member]
         
Significant Accounting Policies [Line Items]          
Expected effective tax rate for continuing operations Range       40.00%  
Minimum [Member]
         
Significant Accounting Policies [Line Items]          
Expected effective tax rate for continuing operations Range       38.00%