Annual report pursuant to Section 13 and 15(d)

Additional Information Regarding Options Outstanding (Detail)

v2.4.0.6
Additional Information Regarding Options Outstanding (Detail) (USD $)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Dec. 31, 2012
$ 0.36 - $ 3.00
Dec. 31, 2012
$ 3.01 - $ 6.00
Dec. 31, 2012
$ 6.01 - $ 9.00
Dec. 31, 2012
$ 9.01 - $ 12.00
Dec. 31, 2012
$ 12.01 - $ 15.00
Dec. 31, 2012
$ 15.01 - $ 18.00
Dec. 31, 2012
$ 18.01 - $ 21.00
Dec. 31, 2012
$ 21.01 - $ 24.00
Dec. 31, 2012
$ 24.01 - $ 25.50
Dec. 31, 2012
$ 0.36 - $ 25.50
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                            
Range of Exercise Prices, Lower Limit         $ 0.36 $ 3.01 $ 6.01 $ 9.01 $ 12.01 $ 15.01 $ 18.01 $ 21.01 $ 24.01 $ 0.36
Range of Exercise Prices, Upper Limit         $ 3.00 $ 6.00 $ 9.00 $ 12.00 $ 15.00 $ 18.00 $ 21.00 $ 24.00 $ 25.50 $ 25.50
Options 1,927,099 1,640,392 1,151,998 1,341,875 1,206,024 500,750 1,500 93,400 87,775 27,750 9,250   650 1,927,099
Weighted Average Contractual Life Remaining (Years)         6 years 6 months 4 years 7 months 6 days 2 years 4 months 24 days 1 year 8 months 12 days 1 year 4 months 24 days 10 months 24 days 1 year 4 months 24 days 0 years 8 months 12 days 5 years 4 months 24 days
Weighted Average Exercise Price $ 4.37 $ 5.01 $ 6.83 $ 5.01 $ 2.40 $ 5.07 $ 7.99 $ 11.80 $ 13.89 $ 16.75 $ 18.89   $ 24.78 $ 4.37
Exercisable Options 707,024 655,228 560,151   223,399 263,300 1,500 93,400 87,775 27,750 9,250   650 707,024
Exercisable Weighted Average Exercise Price $ 6.58 $ 7.56 $ 8.79   $ 1.48 $ 5.05 $ 7.99 $ 11.80 $ 13.89 $ 16.75 $ 18.89   $ 24.78 $ 6.58