Stock Incentive Plans - Summary of the status and shares subject to restricted stock units and average price per share (Details) - RSUs - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock unit, vesting period (in years)	3 years
Number of Shares
Beginning balance, nonvested (in shares)	394,329
Granted (in shares)	157,086
Vested (in shares)	(176,855)
Canceled (in shares)	(13,949)
Ending balance, nonvested (in shares)	360,611	394,329
Weighted-Average Grant Date Fair Value
Beginning balance, nonvested (in USD per share)	$ 120.92
Granted (in USD per share)	159.26
Vested (in USD per share)	116.94
Canceled (in USD per share)	139.61
Ending balance, nonvested (in USD per share)	$ 138.85	$ 120.92
RSUs - Additional Disclosures
Stock-based compensation expense	$ 24,073	$ 23,025	$ 21,190
Expense for nonvested restricted stock units has yet to be recognized	$ 18,627
Expense for nonvested restricted stock units has yet to be recognized, amortized over a weighted-average period (in months)	21 months
Total fair value of shares vested	$ 20,681	21,576	21,173
Tax benefit relating to issuance of common stock for restricted stock units	$ 2,451	$ 939	$ 870
Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock unit, vesting period (in years)	1 year
Number of Shares
Granted (in shares)	9,900	12,430	14,404
Vested (in shares)	(12,639)	(13,740)
Ending balance, nonvested (in shares)	9,845
RSUs - Additional Disclosures
Stock-based compensation expense	$ 1,697	$ 1,560	$ 824
Expense for nonvested restricted stock units has yet to be recognized	$ 596
Expense for nonvested restricted stock units has yet to be recognized, amortized over a weighted-average period (in months)	4 months
Tax benefit relating to issuance of common stock for restricted stock units	$ 270	$ 105