Summary of Stock Option and Restricted Stock Activity (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Options and restricted stock available for grant, Beginning Balance 1,702,174  
Options and restricted stock available for grant, increase to option pool 1,924,511  
Options granted (1,340,686)  
Options expired 186,823  
Options forfeited 316,449  
Options and restricted stock available for grant, Ending Balance 2,207,633 [1] 1,702,174
Number of shares, Beginning Balance 7,707,713  
Options granted, Shares 1,340,686  
Options exercised, Shares (747,899)  
Options expired, Shares (186,823)  
Options forfeited, Shares (316,449)  
Number of shares, Ending Balance 7,797,228 7,707,713
Options exercisable at December 31, 2014 4,811,469 [1]  
Weighted average exercise price, Beginning Balance $ 7.48  
Options granted, Weighted average exercise price $ 9.32  
Options exercised, Weighted average exercise price $ 5.59  
Options expired, Weighted average exercise price $ 11.96  
Options forfeited, Weighted average exercise price $ 6.55  
Weighted average exercise price, Ending Balance $ 7.90 $ 7.48
Options exercisable at December 31, 2014 $ 8.29 [1]  
Weighted average remaining contractual term, End of the period 6 years 6 months 29 days 6 years 11 months 27 days
Weighted Average Remaining Contractual Term, Options exercisable at December 31, 2014 5 years 3 months 29 days [1]  
Aggregate intrinsic value, Outstanding Ending Balance $ 800 $ 17,148
Aggregate intrinsic value, Options exercisable at December 31, 2014 $ 308 [1]  
Restricted Stock    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Restricted stock granted (698,992)  
Restricted stock forfeited 117,354  
[1] Includes 1,199,400 stock options, which have vested based on meeting a combination of certain service and market conditions.