FAIR VALUE MEASUREMENTS - Schedule of financial assets and financial liabilities measured at fair value on a recurring basis (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Jun. 30, 2021
U.S. Treasury and direct obligations of U.S. government agencies
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	$ 29,077	$ 28,838
Corporate bonds
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	110,863	51,899
Commercial paper
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	6,641	21,836
Other securities
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	19,453	10,376
Fair Value, Recurring
Funds held for clients—available-for-sale:
Assets, fair value disclosure	1,715,916	670,315
Fair Value, Recurring | U.S. Treasury and direct obligations of U.S. government agencies
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	29,077	28,838
Fair Value, Recurring | Corporate bonds
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	110,863	51,899
Fair Value, Recurring | Commercial paper
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	6,641	21,836
Fair Value, Recurring | Other securities
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	19,453	10,376
Fair Value, Recurring | Level 1
Funds held for clients—available-for-sale:
Assets, fair value disclosure	1,549,882	557,366
Fair Value, Recurring | Level 1 | U.S. Treasury and direct obligations of U.S. government agencies
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	0	0
Fair Value, Recurring | Level 1 | Corporate bonds
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	0	0
Fair Value, Recurring | Level 1 | Commercial paper
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	0	0
Fair Value, Recurring | Level 1 | Other securities
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	0	0
Fair Value, Recurring | Level 2
Funds held for clients—available-for-sale:
Assets, fair value disclosure	166,034	112,949
Fair Value, Recurring | Level 2 | U.S. Treasury and direct obligations of U.S. government agencies
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	29,077	28,838
Fair Value, Recurring | Level 2 | Corporate bonds
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	110,863	51,899
Fair Value, Recurring | Level 2 | Commercial paper
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	6,641	21,836
Fair Value, Recurring | Level 2 | Other securities
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	19,453	10,376
Fair Value, Recurring | Level 3
Funds held for clients—available-for-sale:
Assets, fair value disclosure	0	0
Fair Value, Recurring | Level 3 | U.S. Treasury and direct obligations of U.S. government agencies
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	0	0
Fair Value, Recurring | Level 3 | Corporate bonds
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	0	0
Fair Value, Recurring | Level 3 | Commercial paper
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	0	0
Fair Value, Recurring | Level 3 | Other securities
Funds held for clients—available-for-sale:
Debt securities, available-for-sale	0	0
Demand deposit accounts and other cash equivalents
Funds held for clients—cash and cash equivalents:
Demand deposit accounts and other cash equivalents	1,549,882	557,366
Demand deposit accounts and other cash equivalents | Fair Value, Recurring
Funds held for clients—cash and cash equivalents:
Demand deposit accounts and other cash equivalents	1,549,882	557,366
Demand deposit accounts and other cash equivalents | Fair Value, Recurring | Level 1
Funds held for clients—cash and cash equivalents:
Demand deposit accounts and other cash equivalents	1,549,882	557,366
Demand deposit accounts and other cash equivalents | Fair Value, Recurring | Level 2
Funds held for clients—cash and cash equivalents:
Demand deposit accounts and other cash equivalents	0	0
Demand deposit accounts and other cash equivalents | Fair Value, Recurring | Level 3
Funds held for clients—cash and cash equivalents:
Demand deposit accounts and other cash equivalents	$ 0	$ 0