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STOCK-BASED COMPENSATION (Details) - USD ($)
3 Months Ended 9 Months Ended 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Mar. 31, 2018
Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Document Fiscal Year Focus     2019      
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount 701,484 338,489 552,337 392,609    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate     0.00% 0.00%    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate     48.95% 52.97%    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate     3.06% 1.97%    
Stock Option Plans [Abstract]            
Number of shares available for grant (in shares) 246,296   246,296      
Weighted-average fair value at the grant date $ 53.13 $ 39.63 $ 53.12 $ 39.33    
Options Activity [Roll Forward]            
Exercised (in shares) (20,180) (39,891) (45,456) (155,710)    
Restricted Stock [Abstract]            
Grant date fair value (in dollars per share)         $ 107.52 $ 51.15
Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]            
Grant date fair value (in dollars per share)         $ 107.52 $ 51.15
Compensation related to stock option and restricted stock plans     $ 9,905,103 $ 3,447,832    
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term     6 years 8 months 10 days 5 years    
Stock Options Plans [Member]            
Stock Option Plans [Abstract]            
Shares of authorized common stock reserved for issuance (in shares) 4,950,000   4,950,000      
Options Activity [Roll Forward]            
Options outstanding, beginning of year (in shares)     497,728      
Granted (in shares)     294,630      
Exercised (in shares)     (45,456)      
Forfeited (in shares)     (6,845)      
Expired (in shares)     (3,052)      
Options outstanding, end of period (in shares) 737,005   737,005   497,728  
Options exercisable, end of period (in shares) 361,283   361,283      
Weighted Average Exercise Price [Roll Forward]            
Options outstanding, beginning of year (in dollars per share)     $ 70.69      
Granted (in dollars per share)     100.79      
Exercised (in dollars per share)     61.94      
Forfeited (in dollars per share)     72.64      
Expired (in dollars per share)     33.91      
Options outstanding, end of period (in dollars per share) $ 83.38   83.38   $ 70.69  
Options exercisable, end of period (in dollars per share) $ 71.25   $ 71.25      
Stock Option Activity Additional Disclosures [Abstract]            
Weighted-average remaining contractual term, Options outstanding, end of period     7 years 15 days      
Weighted-average remaining contractual terms, Options exercisable, end of period     4 years 8 months 1 day      
Aggregate intrinsic value, Options outstanding, end of period $ 13,941,136   $ 13,941,136      
Aggregate intrinsic value, Options exercisable, end of period 11,217,190   11,217,190      
Intrinsic value of options exercised 1,159,858 $ 1,334,062 2,251,405 $ 4,010,659    
Compensation Cost Not yet Recognized [Abstract]            
Total unrecognized stock-based compensation expense related to non-vested stock options 15,500,000   $ 15,500,000      
Weighted average period for recognition     5 years 3 months 29 days      
Schedule of vesting of restricted shares on basis of compounded annual EPS growth [Abstract]            
Weighted average period for recognition     5 years 3 months 29 days      
Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]            
Compensation related to stock option and restricted stock plans 1,361,349 712,286 $ 2,424,986 1,834,513    
Restricted Stock [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock Issued During Period, Shares, Share-based Compensation, Gross         24,456 74,490
Restricted Stock [Abstract]            
Grant date fair value (in dollars per share)     $ 100.99      
Schedule of vesting of restricted shares on basis of compounded annual EPS growth [Abstract]            
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Share-based Awards Other than Options $ 69,100,000   $ 69,100,000      
Summary of the status and changes in restricted stock [Roll Forward]            
Outstanding at Beginning of Year (in shares)     73,810      
Awards granted (in shares)     725,420      
Vested during the period, net of cancellations (in shares)     (39,392)      
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited     0      
Outstanding at End of Period (in shares) 759,838   759,838   73,810  
Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]            
Outstanding at March 31, 2012 (in dollars per share)     $ 65.74      
Grant date fair value (in dollars per share)     100.99      
Vested during the period, net of cancellations (in dollars per share)     55.51      
Cancelled during the period (in dollars per share)     0.00      
Outstanding at June 30, 2012 (in dollars per share) $ 99.93   $ 99.93   $ 65.74  
Compensation related to stock option and restricted stock plans $ 5,565,768 323,201 $ 7,480,117 1,613,319    
Equity Securities [Member]            
Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]            
Compensation related to stock option and restricted stock plans $ 6,927,117 $ 1,035,487 $ 9,905,103 $ 3,447,832    
Performance Shares [Member]            
Compensation Cost Not yet Recognized [Abstract]            
Weighted average period for recognition     4 years 9 months      
Schedule of vesting of restricted shares on basis of compounded annual EPS growth [Abstract]            
Weighted average period for recognition     4 years 9 months      
Maximum [Member] | Stock Options Plans [Member]            
Stock Option Plans [Abstract]            
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period     10 years      
Vesting period     5 years      
Minimum [Member] | Stock Options Plans [Member]            
Stock Option Plans [Abstract]            
Vesting period     3 years