Annual report pursuant to Section 13 and 15(d)

Share-based Compensation - Additional Information (Detail)

v2.4.0.6
Share-based Compensation - Additional Information (Detail) (USD $)
1 Months Ended 12 Months Ended 12 Months Ended 1 Months Ended 12 Months Ended
Mar. 31, 2010
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Dec. 31, 2012
Vested Stock Awards
Dec. 31, 2011
Vested Stock Awards
Dec. 31, 2012
Restricted Stock
Dec. 31, 2012
Performance Based Restricted Stock
Restricted Stock
Dec. 31, 2012
Time Based Restricted Stock
Restricted Stock
Aug. 24, 2011
MTS
Employee
Aug. 24, 2011
MTS
Maximum
Aug. 24, 2011
MTS
Vesting over first year
Aug. 24, 2011
MTS
Vesting over last three years
Dec. 31, 2012
Board of Directors Policy
Dec. 31, 2009
Vesting on the 16th quarter
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                
Stock options vesting period   4 years     4 years     4 years 2 years   4 years       4 years  
Expiration period from grant date   10 years                   10 years        
Percentage of stock options to be vested over 15 quarters         75.00%                      
Percentage of stock options to be vested during remaining period                         25.00% 20.00%   25.00%
Stock options granted                     349,693          
Number of employees authorized for grant                     96          
Weighted average grant-date fair value of options granted   $ 9.78 $ 11.87 $ 5.19                        
Aggregate intrinsic value of stock options   $ 42,700,000 $ 68,600,000 $ 22,900,000                        
Aggregate intrinsic value, outstanding   49,900,000 112,900,000                          
Aggregate intrinsic value of options exercisable   29,900,000 68,300,000                          
Unrecognized non-vested stock options   28,000,000 24,300,000                          
Unrecognized non-vested stock awards recognition period   2 years 8 months 12 days 2 years 9 months 18 days           1 year 3 months 18 days 2 years 9 months 18 days            
Total number of stock options vested during the period   5,821,461 7,274,630     1,349,016 1,416,375                  
Fair value of stock options vested during the period   29,100,000 35,800,000                          
Unrecognized compensation cost                 700,000 26,400,000            
Aggregate intrinsic Value of awards                 5,900,000 29,400,000            
Warrant to purchase common stock 12,500                              
Warrant to purchase shares of common stock exercise price $ 2.00                              
Warrant to purchase shares net exercised $ 8,790                              
Common stock warrant term 5 years