SEGMENT REPORTING (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2021 USD ($) segment	Mar. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			2
Segment Reporting Information [Line Items]
Net interest income	$ 135,669	$ 148,616	$ 397,088	$ 360,339
Provision (benefit) for credit losses - loans	2,700	28,500	22,500	35,700
Non-interest income	23,887	31,542	88,460	74,285
Non-interest expense	80,807	71,790	232,650	204,222
Income before taxes	76,049	79,868	230,398	194,702
Goodwill	71,222		71,222		$ 71,222
Total Assets	14,827,874		14,827,874		13,851,900
Operating segments | Banking Business
Segment Reporting Information [Line Items]
Net interest income	135,092	145,372	390,267	350,184
Provision (benefit) for credit losses - loans	2,700	28,500	22,500	35,700
Non-interest income	16,201	25,259	68,708	57,274
Non-interest expense	64,040	56,661	187,733	160,547
Income before taxes	84,553	85,470	248,742	211,211
Goodwill	35,721		35,721		35,721
Total Assets	13,423,454		13,423,454		13,018,814
Operating segments | Securities Business
Segment Reporting Information [Line Items]
Net interest income	3,847	3,954	13,002	13,137
Provision (benefit) for credit losses - loans	0	0	0	0
Non-interest income	8,369	6,402	20,725	19,087
Non-interest expense	13,282	11,137	35,946	32,656
Income before taxes	(1,066)	(781)	(2,219)	(432)
Goodwill	35,501		35,501		35,501
Total Assets	1,317,859		1,317,859		737,419
Corporate/Eliminations
Segment Reporting Information [Line Items]
Net interest income	(3,270)	(710)	(6,181)	(2,982)
Provision (benefit) for credit losses - loans	0	0	0	0
Non-interest income	(683)	(119)	(973)	(2,076)
Non-interest expense	3,485	3,992	8,971	11,019
Income before taxes	(7,438)	$ (4,821)	(16,125)	$ (16,077)
Goodwill	0		0		0
Total Assets	$ 86,561		$ 86,561		$ 95,667