Annual report pursuant to Section 13 and 15(d)

Common Stock and Stockholders' Equity - Additional Information (Detail)

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Common Stock and Stockholders' Equity - Additional Information (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
 12 Months Ended 0 Months Ended 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2012
2010 Long-Term Incentive Plan [Member]
Sep. 17, 2012
Chief Executive Officer [Member]
Dec. 31, 2012
Performance Units [Member]
Dec. 31, 2011
Performance Units [Member]
Dec. 31, 2010
Performance Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Common stock granted under the 2010 plan       5,800,000        
Restricted stock units, granted         349,651      
Restricted shares to selected key personnel 1,558,347 1,457,039            
Compensation expense related to the performance units $ 7.2 $ 5.9 $ 5.5     $ 0.5 $ 2.1 $ 2.7
Total fair value of the shares vested 7.2 6.9 4.1          
Weighted-average grant-date fair value of shares granted $ 5.37 $ 5.61 $ 4.54          
Non-vested restricted stock awards and restricted stock units 2,393,897,000 2,813,409,000            
Total unrecognized compensation cost of unamortized non-vested stock awards $ 6.8              
Weighted-average vesting period 20 months 3 days              
Performance units under 2010 Long Term Incentive Plan 1,558,347,000         38,429 44,500  
Performance units forfeited 505,626,000         3,955 2,424  
Nominal value           $ 100.00    
Performance at the maximum level 3 years              
Performance period-Awards percentage 200.00%              
Common stock shares reserved for issuance 7,657,479 8,669,723            
Stock option outstanding or exercisable 0 0            
Treasury stock shares 1,411,371 1,709,963