Summary of Significant Accounting Policies - Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Accounting Policies [Abstract]
Loss from continuing operations	$ (6,135)	$ (2,818)	$ (10,188)	$ (7,440)
Income from discontinued operations, net of tax		73		211
Net loss	(6,135)	(2,745)	(10,188)	(7,229)
Less: net income (loss) attributable to non-controlling interest, continuing operations	(226)	(173)	159	(907)
Less: net income attributable to non-controlling interest, discontinued operations		15		45
Net loss attributable to Great Elm Group, Inc.	$ (5,909)	$ (2,587)	$ (10,347)	$ (6,367)
Weighted average shares basic and diluted:
Weighted average shares of common stock outstanding	26,842	25,757	26,963	25,669
Weighted average shares used in computing income (loss) per share	26,842	25,757	26,963	25,669
Basic and diluted income (loss) per share from:
Loss from continuing operations	$ (0.22)	$ (0.10)	$ (0.38)	$ (0.25)
Income from discontinued operations		0.00		0.00
Net loss	$ (0.22)	$ (0.10)	$ (0.38)	$ (0.25)