Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Current taxes
U.S. federal				$ 294
State and local		$ (92)	$ 90	364
Deferred taxes:
U.S. federal		403	5,449	(15,167)
State and local		2,352	(1,316)	(7,338)
Total income tax expense (benefit)		2,663	4,223	(21,847)
Tax Rate Reconciliation
Pre-tax income		$ 67,118	$ 58,046	16,751
Non-recurring tax benefit for valuation allowance reversal				22,771
Non-recurring tax expense to revalue net deferred tax assets from Tax Cuts and Jobs Act				$ 8,626
Income tax expense (benefit) at statutory federal rate		21.00%	21.00%	27.60%	35.00%
Increase (reduction) in income taxes resulting from:
Research and development credit and other credits		(3.20%)	(3.00%)	(6.60%)
Non-deductible expenses		1.60%	1.30%	4.60%
Change in valuation allowance		5.20%	0.30%	(136.00%)
Effect of Tax Cuts and Jobs Act				51.50%
Stock-based compensation expense		(18.30%)	(10.40%)	(58.30%)
State and local income taxes, net of federal income tax benefit		(1.80%)	(2.00%)	(13.50%)
Other		(0.50%)	0.10%	0.30%
Total effective income tax rate		4.00%	7.30%	(130.40%)
Deferred tax assets:
Deferred rent			$ 1,963
Operating lease liability		$ 21,041
Accrued expenses		9,915	4,344
Stock-based compensation		13,351	10,373
Net operating loss carryforwards		13,596	9,980
Federal and state tax credits		16,714	11,977
Intangible assets			385
Total deferred tax assets		74,617	39,022
Valuation allowance		(3,967)	(502)
Net deferred tax assets		70,650	38,520
Deferred tax liabilities:
Deferred contract costs		(41,229)	(27,116)
Operating lease right-of-use assets		(12,607)
Research and development costs		(8,563)	(6,294)
Intangible assets		(781)
Depreciation		(11,269)	(5,581)
Total deferred tax liabilities		(74,449)	(38,991)
Net deferred tax liability		(3,799)	$ (471)
Effect of Tax Cuts and Jobs Act of 2017, Accounting Incomplete, Provisional
Provisional amount of income tax expense attributable to a revaluation of deferred tax assets from change in tax rate	$ 0
State
Deferred tax assets:
Valuation allowance		$ (3,967)