Quarterly report pursuant to Section 13 or 15(d)

Per Share Data and Stockholders' Equity - Additional Information (Detail)

v2.4.0.8
Per Share Data and Stockholders' Equity - Additional Information (Detail) (Common Class A [Member])
In Millions, unless otherwise specified
9 Months Ended
Sep. 30, 2014
Sep. 30, 2013
Common Class A [Member]
   
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]    
Antidilutive stock options excluded in computation of diluted earnings per share 0.4 0.9