Retirement Benefits - Employee stock ownership plan (ESOP) (Details) - USD ($) $ in Thousands	12 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2022
Retirement Benefits [Abstract]
Shares held by ESOP (in shares)	3,422,781	3,779,985	4,125,214
Company matching contributions	$ 116,867	$ 104,237	$ 87,554

Sum of the allocated, committed-to-be-released and suspense shares of the entity held by the plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 718
-SubTopic 40
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480489/718-40-50-1

Name:	us-gaap_EmployeeStockOwnershipPlanESOPSharesInESOP
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant