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Stock Based Compensation - Additional Information (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
3 Months Ended 12 Months Ended 3 Months Ended
Mar. 31, 2013
Performance-Based Restricted Stock
Dec. 31, 2012
Performance-Based Restricted Stock
Performance Period 2010 to 2012
Mar. 31, 2013
Restricted Stock
Service Based Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share based compensation award shares granted in period 115,696   231,727
Share based compensation award granted in period grant-date fair value $ 1.9   $ 3.9
Share based compensation award vesting period from date of grant in cumulative installments     1 year
Share based compensation award cumulative annual installment vesting rate     25.00%
Share based compensation award granted in period weighted average fair value at grant date, per share $ 16.24    
Share based compensation award performance period 3 years    
Share based compensation award end date of the a three-year performance period Dec. 31, 2015    
Performance criteria over the performance period The actual number of shares earned will be based on the Company's performance related to the following performance criteria over the performance period Operating income growth (three-year compound annual growth rate); Total consolidated revenue growth (three-year compound annual growth rate); and Cash flow return on invested capital (three-year average).    
Share based compensation award shares earned in period   78,747  
Share based compensation dividend earned on shares subject to the awards, shares   8,013  
Share based compensation performance-based restricted stock awards, vesting date   Feb. 01, 2013  
Share based compensation performance-based restricted stock awards, grant date   Feb. 01, 2010