Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation Expense - Stock Options Outstanding, Exercisable and Intrinsic Value (Details)

v2.4.0.6
Stock-Based Compensation Expense - Stock Options Outstanding, Exercisable and Intrinsic Value (Details) (Stock Options [Member], USD $)
 12 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Mar. 31, 2011
Apr. 30, 2010
Mar. 31, 2010
Mar. 31, 2013
$5.20 [Member]
Mar. 31, 2013
$9.82 [Member]
Mar. 31, 2013
$12.00 [Member]
Mar. 31, 2013
$21.52 [Member]
Mar. 31, 2013
$5.20 - $21.52 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]                    
Options outstanding (in shares) 1,132,780 2,179,625 2,757,524 0 0 883,904 89,740 104,230 54,906 1,132,780
Options outstanding, weighted average contractual life (in years)           7 years 6 months 18 days 7 years 10 months 28 days 8 years 1 month 13 days 9 years 4 months 2 days 7 years 8 months 16 days
Options outstanding, weighted average exercise price (in dollars per share)           $ 5.20 $ 9.82 $ 12.00 $ 21.52 $ 6.98
Options outstanding, aggregate intrinsic value           $ 15,035,207 $ 1,111,879 $ 1,064,188 $ 37,885 $ 17,249,159
Options vested and exercisable, number exercisable (in shares)           883,904 89,740 10,150 0 983,794
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term                   7 years 7 months 28 days
Options vested and exercisable, weighted average exercise price (in dollars per share)                   5.71
Options vested and exercisable, aggregate intrinsic value           $ 15,035,207 $ 1,111,879 $ 103,632 $ 0 $ 0