| Consolidated Stockholders' Equity Statement [Table Text Block] | 
     
      
       |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Accumulated |  |  |  |  |  |  
       |  |  |  |  |  |  |  |  |  |  | Additional |  |  |  |  |  |  | Other |  |  |  |  |  |  
       |  |  | Common Stock |  |  | Paid-in |  |  | Retained |  |  | Comprehensive |  |  |  |  |  |  
       |  |  | Shares |  |  | Amount |  |  | Capital |  |  | Earnings |  |  | Income(Loss) |  |  | Total |  |  
       | Balances at June 30, 2020 |  |  | 38,453 |  |  | $ | 385 |  |  | $ | 420,536 |  |  | $ | 1,057,470 |  |  | $ | (97,199 | ) |  | $ | 1,381,192 |  |  
       | Cumulative effect adjustments due to adoption of new accounting standards  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (276 | ) |  |  |  |  |  |  | (276 | ) |  
       | Net earnings |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 33,395 |  |  |  |  |  |  |  | 33,395 |  |  
       | Other comprehensive income |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 14,057 |   |  |  | 14,057 |   |  
       | Common stock issued for exercise of options |  |  | 117 |  |  |  | 1 |  |  |  | 13,727 |  |  |  |  |  |  |  |  |  |  |  | 13,728 |  |  
       | Common stock issued for restricted stock awards |  |  | 25 |  |  |  | 0 |  |  |  |  |   |  |  | (4,890 | ) |  |  |  |  |  |  | (4,890 | ) |  
       | Cash dividends |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (12,336 | ) |  |  |  |  |  |  | (12,336 | ) |  
       | Stock-based compensation expense |  |  |  |  |  |  |  |  |  |  | 12,667 |  |  |  |  |  |  |  |  |  |  |  | 12,667 |  |  
       | Common stock issued to employee stock purchase plan |  |  | 6 |  |  |  | 0 |  |  |  | 1,463 |  |  |  |  |  |  |  |  |  |  |  | 1,463 |  |  
       | Employee stock purchase plan expense |  |  |  |  |  |  |  |  |  |  | 286 |  |  |  |  |  |  |  |  |  |  |  | 286 |  |  
       | Balances at September 30, 2020 |  |  | 38,601 |  |  | $ | 386 |  |  | $ | 448,679 |  |  | $ | 1,073,362 |  |  | $ | (83,142 | ) |  | $ | 1,439,285 |  |  
     
      
       |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Accumulated |  |  |  |  |  |  
       |  |  |  |  |  |  |  |  |  |  | Additional |  |  |  |  |  |  | Other |  |  |  |  |  |  
       |  |  | Common Stock |  |  | Paid-in |  |  | Retained |  |  | Comprehensive |  |  |  |  |  |  
       |  |  | Shares |  |  | Amount |  |  | Capital |  |  | Earnings |  |  | Income(Loss) |  |  | Total |  |  
       | Balances at June 30, 2019 |  |  | 37,934 |  |  | $ | 379 |  |  | $ | 316,797 |  |  | $ | 931,934 |  |  | $ | (83,521 | ) |  | $ | 1,165,589 |  |  
       | Cumulative effect adjustments due to adoption of new accounting standards and other |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (879 | ) |  |  |  |  |  |  | (879 | ) |  
       | Net earnings |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 14,398 |  |  |  |  |  |  |  | 14,398 |  |  
       | Other comprehensive loss |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (8,106 | ) |  |  | (8,106 | ) |  
       | Common stock issued for exercise of options |  |  | 94 |  |  |  | 1 |  |  |  | 7,854 |  |  |  |  |  |  |  |  |  |  |  | 7,855 |  |  
       | Common stock issued for restricted stock awards |  |  | 50 |  |  |  | 0 |  |  |  | (0 | ) |  |  | (1,926 | ) |  |  |  |  |  |  | (1,926 | ) |  
       | Cash dividends |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (12,169 | ) |  |  |  |  |  |  | (12,169 | ) |  
       | Stock-based compensation expense |  |  |  |  |  |  |  |  |  |  | 8,267 |  |  |  |  |  |  |  |  |  |  |  | 8,267 |  |  
       | Common stock issued to employee stock purchase plan |  |  | 6 |  |  |  | 0 |  |  |  | 1,096 |  |  |  |  |  |  |  |  |  |  |  | 1,096 |  |  
       | Employee stock purchase plan expense |  |  |  |  |  |  |  |  |  |  | 99 |  |  |  |  |  |  |  |  |  |  |  | 99 |  |  
       | Balances at September 30, 2019 |  |  | 37,803 |  |  | $ | 381 |  |  | $ | 334,112 |  |  | $ | 931,358 |  |  | $ | (91,627 | ) |  | $ | 1,174,224 |  |  | 
| Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] | 
     
      
       |  |  | Unrealized Gains (Losses) on Derivative Instruments |  |  | Foreign Currency Translation Adjustments |  |  | Total |  |  
       | Balance as of June 30, 2020 |  | $ | (13,253 | ) |  | $ | (83,946 | ) |  | $ | (97,199 | ) |  
       | Other comprehensive income (loss) before reclassifications, net of taxes |  |  | 11 |   |  |  | 11,914 |   |  |  | 11,925 |   |  
       | Reclassification from loss on derivatives to interest expense, net of taxes(1) |  |  | 2,132 |  |  |  |  |  |  |  | 2,132 |  |  
       | Balance as of September 30, 2020(2) |  | $ | (11,110 | ) |  | $ | (72,032 | ) |  | $ | (83,142 | ) |  
     
      
       |  |  | Unrealized Gains (Losses) on Derivative Instruments |  |  | Foreign Currency Translation Adjustments |  |  | Total |  |  
       | Balance as of June 30, 2019 |  | $ | (9,537 | ) |  | $ | (73,983 | ) |  | $ | (83,521 | ) |  
       | Other comprehensive income (loss), net of tax before reclassifications |  |  | (504 | ) |  |  | (7,602 | ) |  |  | (8,106 | ) |  
       | Balance as of September 30, 2019(2) |  | $ | (10,041 | ) |  | $ | (81,585 | ) |  | $ | (91,627 | ) |  |