Summary of Significant Accounting Policies - Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Jun. 30, 2022	Jun. 30, 2021
Accounting Policies [Abstract]
Loss from continuing operations		$ (15,037)	$ (8,519)	[1]
Income from discontinued operations, net of tax			649
Net loss		(15,037)	(7,870)	[1]
Less: net loss attributable to non-controlling interest, continuing operations		(144)	(648)	[1]
Less: net income attributable to non-controlling interest, discontinued operations	[1]		53
Net loss attributable to Great Elm Group, Inc.		$ (14,893)	$ (7,275)	[1]
Weighted average shares basic and diluted:
Weighted average shares of common stock outstanding		26,784	25,722
Weighted average shares used in computing income (loss) per share,basic		26,784	25,722
Weighted average shares used in computing income (loss) per share, diluted		26,784	25,722
Basic and diluted income (loss) per share from:
Loss from continuing operations		$ (0.56)	$ (0.31)
Income from discontinued operations			0.03
Net loss per share, basic		(0.56)	(0.28)	[1]
Net loss per share, diluted		$ (0.56)	$ (0.28)	[1]

[1] The As Reported column refects amounts originally reported in our Form 10-K filed on September 21, 2021. The As Adjusted column reflects recast amounts reported in our Form 8-K filed on May 5, 2022.