Balance Sheet Components (Narratives) (Details) - USD ($) $ in Millions	12 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Depreciation expense recognized related to property and equipment	$ 19.5	$ 19.8	$ 23.0

Depreciation expense excluding depreciation of royalty assets.

No definition available.

Name:	extr_DepreciationExpenseExcludingDepreciationOfRoyaltyAssets
Namespace Prefix:	extr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration