Quarterly report pursuant to Section 13 or 15(d)

Equity Transactions - Additional Information (Detail)

v2.4.0.8
Equity Transactions - Additional Information (Detail) (USD $)
In Millions, except Per Share data, unless otherwise specified
 0 Months Ended 1 Months Ended 3 Months Ended 9 Months Ended
May 30, 2013
Sep. 12, 2013
Sep. 30, 2013
Mar. 31, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]              
Stock based compensation expenses     $ 0.4   $ 0.3 $ 1.5 $ 1.0
Common stock, dividend declared per share $ 0.05 $ 0.0525       $ 0.05  
Class A and Class B common stock, payment date Jun. 28, 2013 Oct. 04, 2013 Oct. 04, 2013 Apr. 01, 2013      
Class A and Class B common stock, record date Jun. 14, 2013 Sep. 26, 2013 Sep. 26, 2013 Mar. 25, 2013      
Class A and Class B common stock, expected annual dividend payment     $ 5.1     $ 5.1  
Minimum
              
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]              
Common stock, dividend declared per share   $ 0.0500          
Maximum
              
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]              
Common stock, dividend declared per share   $ 0.0525