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, 2019	Jun. 30, 2018	Jun. 30, 2017
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)	360,611
Granted (in shares)	184,913
Vested (in shares)	(156,079)
Canceled (in shares)	(15,365)
Ending balance, nonvested (in shares)	374,080	360,611
Weighted-Average Grant Date Fair Value
Beginning balance, nonvested (in USD per share)	$ 138.85
Granted (in USD per share)	166.47
Vested (in USD per share)	131.18
Canceled (in USD per share)	154.22
Ending balance, nonvested (in USD per share)	$ 155.07	$ 138.85
RSUs - Additional Disclosures
Stock-based compensation expense	$ 25,258	$ 24,073	$ 23,025
Expense for nonvested restricted stock units has yet to be recognized	$ 21,933
Expense for nonvested restricted stock units has yet to be recognized, amortized over a weighted-average period (in months)	24 months
Total fair value of shares vested	$ 20,475	20,681	21,576
Vested (in shares)	156,079
Tax benefit (cost)	$ 1,548	$ 2,451	$ 939
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)	8,047	9,900	12,430
Vested (in shares)	(9,889)	(12,639)	(13,740)
Ending balance, nonvested (in shares)	8,003
RSUs - Additional Disclosures
Stock-based compensation expense	$ 1,345	$ 1,697	$ 1,560
Expense for nonvested restricted stock units has yet to be recognized	$ 414
Expense for nonvested restricted stock units has yet to be recognized, amortized over a weighted-average period (in months)	4 months
Vested (in shares)	9,889	12,639	13,740
Tax benefit (cost)	$ (82)	$ 270	$ 105